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![Davide Libenzi](/assets/img/avatar_default.png)
It has been thought that the per-user file descriptors limit would also limit the resources that a normal user can request via the epoll interface. Vegard Nossum reported a very simple program (a modified version attached) that can make a normal user to request a pretty large amount of kernel memory, well within the its maximum number of fds. To solve such problem, default limits are now imposed, and /proc based configuration has been introduced. A new directory has been created, named /proc/sys/fs/epoll/ and inside there, there are two configuration points: max_user_instances = Maximum number of devices - per user max_user_watches = Maximum number of "watched" fds - per user The current default for "max_user_watches" limits the memory used by epoll to store "watches", to 1/32 of the amount of the low RAM. As example, a 256MB 32bit machine, will have "max_user_watches" set to roughly 90000. That should be enough to not break existing heavy epoll users. The default value for "max_user_instances" is set to 128, that should be enough too. This also changes the userspace, because a new error code can now come out from EPOLL_CTL_ADD (-ENOSPC). The EMFILE from epoll_create() was already listed, so that should be ok. [akpm@linux-foundation.org: use get_current_user()] Signed-off-by: Davide Libenzi <davidel@xmailserver.org> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Cc: <stable@kernel.org> Cc: Cyrill Gorcunov <gorcunov@gmail.com> Reported-by: Vegard Nossum <vegardno@ifi.uio.no> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1388 lines
38 KiB
C
1388 lines
38 KiB
C
/*
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* fs/eventpoll.c (Efficent event polling implementation)
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* Copyright (C) 2001,...,2007 Davide Libenzi
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* Davide Libenzi <davidel@xmailserver.org>
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*
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*/
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/sched.h>
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#include <linux/fs.h>
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#include <linux/file.h>
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#include <linux/signal.h>
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#include <linux/errno.h>
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#include <linux/mm.h>
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#include <linux/slab.h>
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#include <linux/poll.h>
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#include <linux/string.h>
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#include <linux/list.h>
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#include <linux/hash.h>
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#include <linux/spinlock.h>
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#include <linux/syscalls.h>
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#include <linux/rbtree.h>
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#include <linux/wait.h>
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#include <linux/eventpoll.h>
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#include <linux/mount.h>
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#include <linux/bitops.h>
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#include <linux/mutex.h>
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#include <linux/anon_inodes.h>
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#include <asm/uaccess.h>
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#include <asm/system.h>
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#include <asm/io.h>
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#include <asm/mman.h>
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#include <asm/atomic.h>
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/*
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* LOCKING:
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* There are three level of locking required by epoll :
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*
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* 1) epmutex (mutex)
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* 2) ep->mtx (mutex)
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* 3) ep->lock (spinlock)
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*
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* The acquire order is the one listed above, from 1 to 3.
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* We need a spinlock (ep->lock) because we manipulate objects
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* from inside the poll callback, that might be triggered from
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* a wake_up() that in turn might be called from IRQ context.
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* So we can't sleep inside the poll callback and hence we need
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* a spinlock. During the event transfer loop (from kernel to
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* user space) we could end up sleeping due a copy_to_user(), so
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* we need a lock that will allow us to sleep. This lock is a
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* mutex (ep->mtx). It is acquired during the event transfer loop,
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* during epoll_ctl(EPOLL_CTL_DEL) and during eventpoll_release_file().
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* Then we also need a global mutex to serialize eventpoll_release_file()
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* and ep_free().
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* This mutex is acquired by ep_free() during the epoll file
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* cleanup path and it is also acquired by eventpoll_release_file()
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* if a file has been pushed inside an epoll set and it is then
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* close()d without a previous call toepoll_ctl(EPOLL_CTL_DEL).
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* It is possible to drop the "ep->mtx" and to use the global
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* mutex "epmutex" (together with "ep->lock") to have it working,
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* but having "ep->mtx" will make the interface more scalable.
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* Events that require holding "epmutex" are very rare, while for
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* normal operations the epoll private "ep->mtx" will guarantee
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* a better scalability.
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*/
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#define DEBUG_EPOLL 0
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#if DEBUG_EPOLL > 0
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#define DPRINTK(x) printk x
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#define DNPRINTK(n, x) do { if ((n) <= DEBUG_EPOLL) printk x; } while (0)
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#else /* #if DEBUG_EPOLL > 0 */
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#define DPRINTK(x) (void) 0
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#define DNPRINTK(n, x) (void) 0
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#endif /* #if DEBUG_EPOLL > 0 */
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#define DEBUG_EPI 0
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#if DEBUG_EPI != 0
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#define EPI_SLAB_DEBUG (SLAB_DEBUG_FREE | SLAB_RED_ZONE /* | SLAB_POISON */)
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#else /* #if DEBUG_EPI != 0 */
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#define EPI_SLAB_DEBUG 0
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#endif /* #if DEBUG_EPI != 0 */
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/* Epoll private bits inside the event mask */
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#define EP_PRIVATE_BITS (EPOLLONESHOT | EPOLLET)
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/* Maximum number of poll wake up nests we are allowing */
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#define EP_MAX_POLLWAKE_NESTS 4
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/* Maximum msec timeout value storeable in a long int */
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#define EP_MAX_MSTIMEO min(1000ULL * MAX_SCHEDULE_TIMEOUT / HZ, (LONG_MAX - 999ULL) / HZ)
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#define EP_MAX_EVENTS (INT_MAX / sizeof(struct epoll_event))
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#define EP_UNACTIVE_PTR ((void *) -1L)
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#define EP_ITEM_COST (sizeof(struct epitem) + sizeof(struct eppoll_entry))
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struct epoll_filefd {
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struct file *file;
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int fd;
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};
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/*
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* Node that is linked into the "wake_task_list" member of the "struct poll_safewake".
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* It is used to keep track on all tasks that are currently inside the wake_up() code
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* to 1) short-circuit the one coming from the same task and same wait queue head
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* (loop) 2) allow a maximum number of epoll descriptors inclusion nesting
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* 3) let go the ones coming from other tasks.
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*/
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struct wake_task_node {
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struct list_head llink;
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struct task_struct *task;
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wait_queue_head_t *wq;
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};
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/*
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* This is used to implement the safe poll wake up avoiding to reenter
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* the poll callback from inside wake_up().
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*/
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struct poll_safewake {
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struct list_head wake_task_list;
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spinlock_t lock;
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};
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/*
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* Each file descriptor added to the eventpoll interface will
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* have an entry of this type linked to the "rbr" RB tree.
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*/
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struct epitem {
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/* RB tree node used to link this structure to the eventpoll RB tree */
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struct rb_node rbn;
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/* List header used to link this structure to the eventpoll ready list */
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struct list_head rdllink;
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/*
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* Works together "struct eventpoll"->ovflist in keeping the
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* single linked chain of items.
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*/
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struct epitem *next;
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/* The file descriptor information this item refers to */
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struct epoll_filefd ffd;
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/* Number of active wait queue attached to poll operations */
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int nwait;
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/* List containing poll wait queues */
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struct list_head pwqlist;
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/* The "container" of this item */
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struct eventpoll *ep;
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/* List header used to link this item to the "struct file" items list */
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struct list_head fllink;
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/* The structure that describe the interested events and the source fd */
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struct epoll_event event;
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};
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/*
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* This structure is stored inside the "private_data" member of the file
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* structure and rapresent the main data sructure for the eventpoll
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* interface.
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*/
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struct eventpoll {
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/* Protect the this structure access */
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spinlock_t lock;
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/*
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* This mutex is used to ensure that files are not removed
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* while epoll is using them. This is held during the event
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* collection loop, the file cleanup path, the epoll file exit
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* code and the ctl operations.
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*/
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struct mutex mtx;
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/* Wait queue used by sys_epoll_wait() */
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wait_queue_head_t wq;
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/* Wait queue used by file->poll() */
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wait_queue_head_t poll_wait;
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/* List of ready file descriptors */
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struct list_head rdllist;
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/* RB tree root used to store monitored fd structs */
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struct rb_root rbr;
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/*
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* This is a single linked list that chains all the "struct epitem" that
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* happened while transfering ready events to userspace w/out
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* holding ->lock.
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*/
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struct epitem *ovflist;
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/* The user that created the eventpoll descriptor */
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struct user_struct *user;
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};
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/* Wait structure used by the poll hooks */
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struct eppoll_entry {
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/* List header used to link this structure to the "struct epitem" */
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struct list_head llink;
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/* The "base" pointer is set to the container "struct epitem" */
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void *base;
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/*
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* Wait queue item that will be linked to the target file wait
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* queue head.
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*/
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wait_queue_t wait;
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/* The wait queue head that linked the "wait" wait queue item */
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wait_queue_head_t *whead;
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};
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/* Wrapper struct used by poll queueing */
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struct ep_pqueue {
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poll_table pt;
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struct epitem *epi;
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};
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/*
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* Configuration options available inside /proc/sys/fs/epoll/
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*/
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/* Maximum number of epoll devices, per user */
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static int max_user_instances __read_mostly;
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/* Maximum number of epoll watched descriptors, per user */
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static int max_user_watches __read_mostly;
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/*
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* This mutex is used to serialize ep_free() and eventpoll_release_file().
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*/
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static DEFINE_MUTEX(epmutex);
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/* Safe wake up implementation */
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static struct poll_safewake psw;
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/* Slab cache used to allocate "struct epitem" */
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static struct kmem_cache *epi_cache __read_mostly;
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/* Slab cache used to allocate "struct eppoll_entry" */
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static struct kmem_cache *pwq_cache __read_mostly;
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#ifdef CONFIG_SYSCTL
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#include <linux/sysctl.h>
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static int zero;
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ctl_table epoll_table[] = {
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{
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.procname = "max_user_instances",
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.data = &max_user_instances,
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.maxlen = sizeof(int),
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.mode = 0644,
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.proc_handler = &proc_dointvec_minmax,
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.extra1 = &zero,
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},
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{
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.procname = "max_user_watches",
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.data = &max_user_watches,
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.maxlen = sizeof(int),
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.mode = 0644,
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.proc_handler = &proc_dointvec_minmax,
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.extra1 = &zero,
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},
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{ .ctl_name = 0 }
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};
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#endif /* CONFIG_SYSCTL */
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/* Setup the structure that is used as key for the RB tree */
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static inline void ep_set_ffd(struct epoll_filefd *ffd,
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struct file *file, int fd)
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{
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ffd->file = file;
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ffd->fd = fd;
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}
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/* Compare RB tree keys */
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static inline int ep_cmp_ffd(struct epoll_filefd *p1,
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struct epoll_filefd *p2)
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{
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return (p1->file > p2->file ? +1:
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(p1->file < p2->file ? -1 : p1->fd - p2->fd));
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}
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/* Tells us if the item is currently linked */
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static inline int ep_is_linked(struct list_head *p)
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{
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return !list_empty(p);
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}
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/* Get the "struct epitem" from a wait queue pointer */
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static inline struct epitem *ep_item_from_wait(wait_queue_t *p)
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{
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return container_of(p, struct eppoll_entry, wait)->base;
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}
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/* Get the "struct epitem" from an epoll queue wrapper */
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static inline struct epitem *ep_item_from_epqueue(poll_table *p)
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{
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return container_of(p, struct ep_pqueue, pt)->epi;
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}
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/* Tells if the epoll_ctl(2) operation needs an event copy from userspace */
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static inline int ep_op_has_event(int op)
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{
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return op != EPOLL_CTL_DEL;
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}
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/* Initialize the poll safe wake up structure */
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static void ep_poll_safewake_init(struct poll_safewake *psw)
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{
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INIT_LIST_HEAD(&psw->wake_task_list);
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spin_lock_init(&psw->lock);
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}
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/*
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* Perform a safe wake up of the poll wait list. The problem is that
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* with the new callback'd wake up system, it is possible that the
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* poll callback is reentered from inside the call to wake_up() done
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* on the poll wait queue head. The rule is that we cannot reenter the
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* wake up code from the same task more than EP_MAX_POLLWAKE_NESTS times,
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* and we cannot reenter the same wait queue head at all. This will
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* enable to have a hierarchy of epoll file descriptor of no more than
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* EP_MAX_POLLWAKE_NESTS deep. We need the irq version of the spin lock
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* because this one gets called by the poll callback, that in turn is called
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* from inside a wake_up(), that might be called from irq context.
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*/
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static void ep_poll_safewake(struct poll_safewake *psw, wait_queue_head_t *wq)
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{
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int wake_nests = 0;
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unsigned long flags;
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struct task_struct *this_task = current;
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struct list_head *lsthead = &psw->wake_task_list;
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struct wake_task_node *tncur;
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struct wake_task_node tnode;
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spin_lock_irqsave(&psw->lock, flags);
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/* Try to see if the current task is already inside this wakeup call */
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list_for_each_entry(tncur, lsthead, llink) {
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if (tncur->wq == wq ||
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(tncur->task == this_task && ++wake_nests > EP_MAX_POLLWAKE_NESTS)) {
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/*
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* Ops ... loop detected or maximum nest level reached.
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* We abort this wake by breaking the cycle itself.
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*/
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spin_unlock_irqrestore(&psw->lock, flags);
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return;
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}
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}
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/* Add the current task to the list */
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tnode.task = this_task;
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tnode.wq = wq;
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list_add(&tnode.llink, lsthead);
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spin_unlock_irqrestore(&psw->lock, flags);
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/* Do really wake up now */
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wake_up_nested(wq, 1 + wake_nests);
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/* Remove the current task from the list */
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spin_lock_irqsave(&psw->lock, flags);
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list_del(&tnode.llink);
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spin_unlock_irqrestore(&psw->lock, flags);
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}
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/*
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* This function unregister poll callbacks from the associated file descriptor.
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* Since this must be called without holding "ep->lock" the atomic exchange trick
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* will protect us from multiple unregister.
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*/
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static void ep_unregister_pollwait(struct eventpoll *ep, struct epitem *epi)
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{
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int nwait;
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struct list_head *lsthead = &epi->pwqlist;
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struct eppoll_entry *pwq;
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/* This is called without locks, so we need the atomic exchange */
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nwait = xchg(&epi->nwait, 0);
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if (nwait) {
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while (!list_empty(lsthead)) {
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pwq = list_first_entry(lsthead, struct eppoll_entry, llink);
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list_del_init(&pwq->llink);
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remove_wait_queue(pwq->whead, &pwq->wait);
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kmem_cache_free(pwq_cache, pwq);
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}
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}
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}
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/*
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* Removes a "struct epitem" from the eventpoll RB tree and deallocates
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* all the associated resources. Must be called with "mtx" held.
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*/
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static int ep_remove(struct eventpoll *ep, struct epitem *epi)
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{
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unsigned long flags;
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struct file *file = epi->ffd.file;
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/*
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* Removes poll wait queue hooks. We _have_ to do this without holding
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* the "ep->lock" otherwise a deadlock might occur. This because of the
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* sequence of the lock acquisition. Here we do "ep->lock" then the wait
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* queue head lock when unregistering the wait queue. The wakeup callback
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* will run by holding the wait queue head lock and will call our callback
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* that will try to get "ep->lock".
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*/
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ep_unregister_pollwait(ep, epi);
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/* Remove the current item from the list of epoll hooks */
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spin_lock(&file->f_ep_lock);
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if (ep_is_linked(&epi->fllink))
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list_del_init(&epi->fllink);
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spin_unlock(&file->f_ep_lock);
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rb_erase(&epi->rbn, &ep->rbr);
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spin_lock_irqsave(&ep->lock, flags);
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if (ep_is_linked(&epi->rdllink))
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list_del_init(&epi->rdllink);
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spin_unlock_irqrestore(&ep->lock, flags);
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/* At this point it is safe to free the eventpoll item */
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kmem_cache_free(epi_cache, epi);
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atomic_dec(&ep->user->epoll_watches);
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DNPRINTK(3, (KERN_INFO "[%p] eventpoll: ep_remove(%p, %p)\n",
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current, ep, file));
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return 0;
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}
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static void ep_free(struct eventpoll *ep)
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{
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struct rb_node *rbp;
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struct epitem *epi;
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/* We need to release all tasks waiting for these file */
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if (waitqueue_active(&ep->poll_wait))
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ep_poll_safewake(&psw, &ep->poll_wait);
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/*
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* We need to lock this because we could be hit by
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* eventpoll_release_file() while we're freeing the "struct eventpoll".
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* We do not need to hold "ep->mtx" here because the epoll file
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* is on the way to be removed and no one has references to it
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* anymore. The only hit might come from eventpoll_release_file() but
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* holding "epmutex" is sufficent here.
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*/
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mutex_lock(&epmutex);
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/*
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* Walks through the whole tree by unregistering poll callbacks.
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*/
|
|
for (rbp = rb_first(&ep->rbr); rbp; rbp = rb_next(rbp)) {
|
|
epi = rb_entry(rbp, struct epitem, rbn);
|
|
|
|
ep_unregister_pollwait(ep, epi);
|
|
}
|
|
|
|
/*
|
|
* Walks through the whole tree by freeing each "struct epitem". At this
|
|
* point we are sure no poll callbacks will be lingering around, and also by
|
|
* holding "epmutex" we can be sure that no file cleanup code will hit
|
|
* us during this operation. So we can avoid the lock on "ep->lock".
|
|
*/
|
|
while ((rbp = rb_first(&ep->rbr)) != NULL) {
|
|
epi = rb_entry(rbp, struct epitem, rbn);
|
|
ep_remove(ep, epi);
|
|
}
|
|
|
|
mutex_unlock(&epmutex);
|
|
mutex_destroy(&ep->mtx);
|
|
atomic_dec(&ep->user->epoll_devs);
|
|
free_uid(ep->user);
|
|
kfree(ep);
|
|
}
|
|
|
|
static int ep_eventpoll_release(struct inode *inode, struct file *file)
|
|
{
|
|
struct eventpoll *ep = file->private_data;
|
|
|
|
if (ep)
|
|
ep_free(ep);
|
|
|
|
DNPRINTK(3, (KERN_INFO "[%p] eventpoll: close() ep=%p\n", current, ep));
|
|
return 0;
|
|
}
|
|
|
|
static unsigned int ep_eventpoll_poll(struct file *file, poll_table *wait)
|
|
{
|
|
unsigned int pollflags = 0;
|
|
unsigned long flags;
|
|
struct eventpoll *ep = file->private_data;
|
|
|
|
/* Insert inside our poll wait queue */
|
|
poll_wait(file, &ep->poll_wait, wait);
|
|
|
|
/* Check our condition */
|
|
spin_lock_irqsave(&ep->lock, flags);
|
|
if (!list_empty(&ep->rdllist))
|
|
pollflags = POLLIN | POLLRDNORM;
|
|
spin_unlock_irqrestore(&ep->lock, flags);
|
|
|
|
return pollflags;
|
|
}
|
|
|
|
/* File callbacks that implement the eventpoll file behaviour */
|
|
static const struct file_operations eventpoll_fops = {
|
|
.release = ep_eventpoll_release,
|
|
.poll = ep_eventpoll_poll
|
|
};
|
|
|
|
/* Fast test to see if the file is an evenpoll file */
|
|
static inline int is_file_epoll(struct file *f)
|
|
{
|
|
return f->f_op == &eventpoll_fops;
|
|
}
|
|
|
|
/*
|
|
* This is called from eventpoll_release() to unlink files from the eventpoll
|
|
* interface. We need to have this facility to cleanup correctly files that are
|
|
* closed without being removed from the eventpoll interface.
|
|
*/
|
|
void eventpoll_release_file(struct file *file)
|
|
{
|
|
struct list_head *lsthead = &file->f_ep_links;
|
|
struct eventpoll *ep;
|
|
struct epitem *epi;
|
|
|
|
/*
|
|
* We don't want to get "file->f_ep_lock" because it is not
|
|
* necessary. It is not necessary because we're in the "struct file"
|
|
* cleanup path, and this means that noone is using this file anymore.
|
|
* So, for example, epoll_ctl() cannot hit here sicne if we reach this
|
|
* point, the file counter already went to zero and fget() would fail.
|
|
* The only hit might come from ep_free() but by holding the mutex
|
|
* will correctly serialize the operation. We do need to acquire
|
|
* "ep->mtx" after "epmutex" because ep_remove() requires it when called
|
|
* from anywhere but ep_free().
|
|
*/
|
|
mutex_lock(&epmutex);
|
|
|
|
while (!list_empty(lsthead)) {
|
|
epi = list_first_entry(lsthead, struct epitem, fllink);
|
|
|
|
ep = epi->ep;
|
|
list_del_init(&epi->fllink);
|
|
mutex_lock(&ep->mtx);
|
|
ep_remove(ep, epi);
|
|
mutex_unlock(&ep->mtx);
|
|
}
|
|
|
|
mutex_unlock(&epmutex);
|
|
}
|
|
|
|
static int ep_alloc(struct eventpoll **pep)
|
|
{
|
|
int error;
|
|
struct user_struct *user;
|
|
struct eventpoll *ep;
|
|
|
|
user = get_current_user();
|
|
error = -EMFILE;
|
|
if (unlikely(atomic_read(&user->epoll_devs) >=
|
|
max_user_instances))
|
|
goto free_uid;
|
|
error = -ENOMEM;
|
|
ep = kzalloc(sizeof(*ep), GFP_KERNEL);
|
|
if (unlikely(!ep))
|
|
goto free_uid;
|
|
|
|
spin_lock_init(&ep->lock);
|
|
mutex_init(&ep->mtx);
|
|
init_waitqueue_head(&ep->wq);
|
|
init_waitqueue_head(&ep->poll_wait);
|
|
INIT_LIST_HEAD(&ep->rdllist);
|
|
ep->rbr = RB_ROOT;
|
|
ep->ovflist = EP_UNACTIVE_PTR;
|
|
ep->user = user;
|
|
|
|
*pep = ep;
|
|
|
|
DNPRINTK(3, (KERN_INFO "[%p] eventpoll: ep_alloc() ep=%p\n",
|
|
current, ep));
|
|
return 0;
|
|
|
|
free_uid:
|
|
free_uid(user);
|
|
return error;
|
|
}
|
|
|
|
/*
|
|
* Search the file inside the eventpoll tree. The RB tree operations
|
|
* are protected by the "mtx" mutex, and ep_find() must be called with
|
|
* "mtx" held.
|
|
*/
|
|
static struct epitem *ep_find(struct eventpoll *ep, struct file *file, int fd)
|
|
{
|
|
int kcmp;
|
|
struct rb_node *rbp;
|
|
struct epitem *epi, *epir = NULL;
|
|
struct epoll_filefd ffd;
|
|
|
|
ep_set_ffd(&ffd, file, fd);
|
|
for (rbp = ep->rbr.rb_node; rbp; ) {
|
|
epi = rb_entry(rbp, struct epitem, rbn);
|
|
kcmp = ep_cmp_ffd(&ffd, &epi->ffd);
|
|
if (kcmp > 0)
|
|
rbp = rbp->rb_right;
|
|
else if (kcmp < 0)
|
|
rbp = rbp->rb_left;
|
|
else {
|
|
epir = epi;
|
|
break;
|
|
}
|
|
}
|
|
|
|
DNPRINTK(3, (KERN_INFO "[%p] eventpoll: ep_find(%p) -> %p\n",
|
|
current, file, epir));
|
|
|
|
return epir;
|
|
}
|
|
|
|
/*
|
|
* This is the callback that is passed to the wait queue wakeup
|
|
* machanism. It is called by the stored file descriptors when they
|
|
* have events to report.
|
|
*/
|
|
static int ep_poll_callback(wait_queue_t *wait, unsigned mode, int sync, void *key)
|
|
{
|
|
int pwake = 0;
|
|
unsigned long flags;
|
|
struct epitem *epi = ep_item_from_wait(wait);
|
|
struct eventpoll *ep = epi->ep;
|
|
|
|
DNPRINTK(3, (KERN_INFO "[%p] eventpoll: poll_callback(%p) epi=%p ep=%p\n",
|
|
current, epi->ffd.file, epi, ep));
|
|
|
|
spin_lock_irqsave(&ep->lock, flags);
|
|
|
|
/*
|
|
* If the event mask does not contain any poll(2) event, we consider the
|
|
* descriptor to be disabled. This condition is likely the effect of the
|
|
* EPOLLONESHOT bit that disables the descriptor when an event is received,
|
|
* until the next EPOLL_CTL_MOD will be issued.
|
|
*/
|
|
if (!(epi->event.events & ~EP_PRIVATE_BITS))
|
|
goto out_unlock;
|
|
|
|
/*
|
|
* If we are trasfering events to userspace, we can hold no locks
|
|
* (because we're accessing user memory, and because of linux f_op->poll()
|
|
* semantics). All the events that happens during that period of time are
|
|
* chained in ep->ovflist and requeued later on.
|
|
*/
|
|
if (unlikely(ep->ovflist != EP_UNACTIVE_PTR)) {
|
|
if (epi->next == EP_UNACTIVE_PTR) {
|
|
epi->next = ep->ovflist;
|
|
ep->ovflist = epi;
|
|
}
|
|
goto out_unlock;
|
|
}
|
|
|
|
/* If this file is already in the ready list we exit soon */
|
|
if (ep_is_linked(&epi->rdllink))
|
|
goto is_linked;
|
|
|
|
list_add_tail(&epi->rdllink, &ep->rdllist);
|
|
|
|
is_linked:
|
|
/*
|
|
* Wake up ( if active ) both the eventpoll wait list and the ->poll()
|
|
* wait list.
|
|
*/
|
|
if (waitqueue_active(&ep->wq))
|
|
wake_up_locked(&ep->wq);
|
|
if (waitqueue_active(&ep->poll_wait))
|
|
pwake++;
|
|
|
|
out_unlock:
|
|
spin_unlock_irqrestore(&ep->lock, flags);
|
|
|
|
/* We have to call this outside the lock */
|
|
if (pwake)
|
|
ep_poll_safewake(&psw, &ep->poll_wait);
|
|
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* This is the callback that is used to add our wait queue to the
|
|
* target file wakeup lists.
|
|
*/
|
|
static void ep_ptable_queue_proc(struct file *file, wait_queue_head_t *whead,
|
|
poll_table *pt)
|
|
{
|
|
struct epitem *epi = ep_item_from_epqueue(pt);
|
|
struct eppoll_entry *pwq;
|
|
|
|
if (epi->nwait >= 0 && (pwq = kmem_cache_alloc(pwq_cache, GFP_KERNEL))) {
|
|
init_waitqueue_func_entry(&pwq->wait, ep_poll_callback);
|
|
pwq->whead = whead;
|
|
pwq->base = epi;
|
|
add_wait_queue(whead, &pwq->wait);
|
|
list_add_tail(&pwq->llink, &epi->pwqlist);
|
|
epi->nwait++;
|
|
} else {
|
|
/* We have to signal that an error occurred */
|
|
epi->nwait = -1;
|
|
}
|
|
}
|
|
|
|
static void ep_rbtree_insert(struct eventpoll *ep, struct epitem *epi)
|
|
{
|
|
int kcmp;
|
|
struct rb_node **p = &ep->rbr.rb_node, *parent = NULL;
|
|
struct epitem *epic;
|
|
|
|
while (*p) {
|
|
parent = *p;
|
|
epic = rb_entry(parent, struct epitem, rbn);
|
|
kcmp = ep_cmp_ffd(&epi->ffd, &epic->ffd);
|
|
if (kcmp > 0)
|
|
p = &parent->rb_right;
|
|
else
|
|
p = &parent->rb_left;
|
|
}
|
|
rb_link_node(&epi->rbn, parent, p);
|
|
rb_insert_color(&epi->rbn, &ep->rbr);
|
|
}
|
|
|
|
/*
|
|
* Must be called with "mtx" held.
|
|
*/
|
|
static int ep_insert(struct eventpoll *ep, struct epoll_event *event,
|
|
struct file *tfile, int fd)
|
|
{
|
|
int error, revents, pwake = 0;
|
|
unsigned long flags;
|
|
struct epitem *epi;
|
|
struct ep_pqueue epq;
|
|
|
|
if (unlikely(atomic_read(&ep->user->epoll_watches) >=
|
|
max_user_watches))
|
|
return -ENOSPC;
|
|
if (!(epi = kmem_cache_alloc(epi_cache, GFP_KERNEL)))
|
|
return -ENOMEM;
|
|
|
|
/* Item initialization follow here ... */
|
|
INIT_LIST_HEAD(&epi->rdllink);
|
|
INIT_LIST_HEAD(&epi->fllink);
|
|
INIT_LIST_HEAD(&epi->pwqlist);
|
|
epi->ep = ep;
|
|
ep_set_ffd(&epi->ffd, tfile, fd);
|
|
epi->event = *event;
|
|
epi->nwait = 0;
|
|
epi->next = EP_UNACTIVE_PTR;
|
|
|
|
/* Initialize the poll table using the queue callback */
|
|
epq.epi = epi;
|
|
init_poll_funcptr(&epq.pt, ep_ptable_queue_proc);
|
|
|
|
/*
|
|
* Attach the item to the poll hooks and get current event bits.
|
|
* We can safely use the file* here because its usage count has
|
|
* been increased by the caller of this function. Note that after
|
|
* this operation completes, the poll callback can start hitting
|
|
* the new item.
|
|
*/
|
|
revents = tfile->f_op->poll(tfile, &epq.pt);
|
|
|
|
/*
|
|
* We have to check if something went wrong during the poll wait queue
|
|
* install process. Namely an allocation for a wait queue failed due
|
|
* high memory pressure.
|
|
*/
|
|
error = -ENOMEM;
|
|
if (epi->nwait < 0)
|
|
goto error_unregister;
|
|
|
|
/* Add the current item to the list of active epoll hook for this file */
|
|
spin_lock(&tfile->f_ep_lock);
|
|
list_add_tail(&epi->fllink, &tfile->f_ep_links);
|
|
spin_unlock(&tfile->f_ep_lock);
|
|
|
|
/*
|
|
* Add the current item to the RB tree. All RB tree operations are
|
|
* protected by "mtx", and ep_insert() is called with "mtx" held.
|
|
*/
|
|
ep_rbtree_insert(ep, epi);
|
|
|
|
/* We have to drop the new item inside our item list to keep track of it */
|
|
spin_lock_irqsave(&ep->lock, flags);
|
|
|
|
/* If the file is already "ready" we drop it inside the ready list */
|
|
if ((revents & event->events) && !ep_is_linked(&epi->rdllink)) {
|
|
list_add_tail(&epi->rdllink, &ep->rdllist);
|
|
|
|
/* Notify waiting tasks that events are available */
|
|
if (waitqueue_active(&ep->wq))
|
|
wake_up_locked(&ep->wq);
|
|
if (waitqueue_active(&ep->poll_wait))
|
|
pwake++;
|
|
}
|
|
|
|
spin_unlock_irqrestore(&ep->lock, flags);
|
|
|
|
atomic_inc(&ep->user->epoll_watches);
|
|
|
|
/* We have to call this outside the lock */
|
|
if (pwake)
|
|
ep_poll_safewake(&psw, &ep->poll_wait);
|
|
|
|
DNPRINTK(3, (KERN_INFO "[%p] eventpoll: ep_insert(%p, %p, %d)\n",
|
|
current, ep, tfile, fd));
|
|
|
|
return 0;
|
|
|
|
error_unregister:
|
|
ep_unregister_pollwait(ep, epi);
|
|
|
|
/*
|
|
* We need to do this because an event could have been arrived on some
|
|
* allocated wait queue. Note that we don't care about the ep->ovflist
|
|
* list, since that is used/cleaned only inside a section bound by "mtx".
|
|
* And ep_insert() is called with "mtx" held.
|
|
*/
|
|
spin_lock_irqsave(&ep->lock, flags);
|
|
if (ep_is_linked(&epi->rdllink))
|
|
list_del_init(&epi->rdllink);
|
|
spin_unlock_irqrestore(&ep->lock, flags);
|
|
|
|
kmem_cache_free(epi_cache, epi);
|
|
|
|
return error;
|
|
}
|
|
|
|
/*
|
|
* Modify the interest event mask by dropping an event if the new mask
|
|
* has a match in the current file status. Must be called with "mtx" held.
|
|
*/
|
|
static int ep_modify(struct eventpoll *ep, struct epitem *epi, struct epoll_event *event)
|
|
{
|
|
int pwake = 0;
|
|
unsigned int revents;
|
|
unsigned long flags;
|
|
|
|
/*
|
|
* Set the new event interest mask before calling f_op->poll(), otherwise
|
|
* a potential race might occur. In fact if we do this operation inside
|
|
* the lock, an event might happen between the f_op->poll() call and the
|
|
* new event set registering.
|
|
*/
|
|
epi->event.events = event->events;
|
|
|
|
/*
|
|
* Get current event bits. We can safely use the file* here because
|
|
* its usage count has been increased by the caller of this function.
|
|
*/
|
|
revents = epi->ffd.file->f_op->poll(epi->ffd.file, NULL);
|
|
|
|
spin_lock_irqsave(&ep->lock, flags);
|
|
|
|
/* Copy the data member from inside the lock */
|
|
epi->event.data = event->data;
|
|
|
|
/*
|
|
* If the item is "hot" and it is not registered inside the ready
|
|
* list, push it inside.
|
|
*/
|
|
if (revents & event->events) {
|
|
if (!ep_is_linked(&epi->rdllink)) {
|
|
list_add_tail(&epi->rdllink, &ep->rdllist);
|
|
|
|
/* Notify waiting tasks that events are available */
|
|
if (waitqueue_active(&ep->wq))
|
|
wake_up_locked(&ep->wq);
|
|
if (waitqueue_active(&ep->poll_wait))
|
|
pwake++;
|
|
}
|
|
}
|
|
spin_unlock_irqrestore(&ep->lock, flags);
|
|
|
|
/* We have to call this outside the lock */
|
|
if (pwake)
|
|
ep_poll_safewake(&psw, &ep->poll_wait);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int ep_send_events(struct eventpoll *ep, struct epoll_event __user *events,
|
|
int maxevents)
|
|
{
|
|
int eventcnt, error = -EFAULT, pwake = 0;
|
|
unsigned int revents;
|
|
unsigned long flags;
|
|
struct epitem *epi, *nepi;
|
|
struct list_head txlist;
|
|
|
|
INIT_LIST_HEAD(&txlist);
|
|
|
|
/*
|
|
* We need to lock this because we could be hit by
|
|
* eventpoll_release_file() and epoll_ctl(EPOLL_CTL_DEL).
|
|
*/
|
|
mutex_lock(&ep->mtx);
|
|
|
|
/*
|
|
* Steal the ready list, and re-init the original one to the
|
|
* empty list. Also, set ep->ovflist to NULL so that events
|
|
* happening while looping w/out locks, are not lost. We cannot
|
|
* have the poll callback to queue directly on ep->rdllist,
|
|
* because we are doing it in the loop below, in a lockless way.
|
|
*/
|
|
spin_lock_irqsave(&ep->lock, flags);
|
|
list_splice(&ep->rdllist, &txlist);
|
|
INIT_LIST_HEAD(&ep->rdllist);
|
|
ep->ovflist = NULL;
|
|
spin_unlock_irqrestore(&ep->lock, flags);
|
|
|
|
/*
|
|
* We can loop without lock because this is a task private list.
|
|
* We just splice'd out the ep->rdllist in ep_collect_ready_items().
|
|
* Items cannot vanish during the loop because we are holding "mtx".
|
|
*/
|
|
for (eventcnt = 0; !list_empty(&txlist) && eventcnt < maxevents;) {
|
|
epi = list_first_entry(&txlist, struct epitem, rdllink);
|
|
|
|
list_del_init(&epi->rdllink);
|
|
|
|
/*
|
|
* Get the ready file event set. We can safely use the file
|
|
* because we are holding the "mtx" and this will guarantee
|
|
* that both the file and the item will not vanish.
|
|
*/
|
|
revents = epi->ffd.file->f_op->poll(epi->ffd.file, NULL);
|
|
revents &= epi->event.events;
|
|
|
|
/*
|
|
* Is the event mask intersect the caller-requested one,
|
|
* deliver the event to userspace. Again, we are holding
|
|
* "mtx", so no operations coming from userspace can change
|
|
* the item.
|
|
*/
|
|
if (revents) {
|
|
if (__put_user(revents,
|
|
&events[eventcnt].events) ||
|
|
__put_user(epi->event.data,
|
|
&events[eventcnt].data))
|
|
goto errxit;
|
|
if (epi->event.events & EPOLLONESHOT)
|
|
epi->event.events &= EP_PRIVATE_BITS;
|
|
eventcnt++;
|
|
}
|
|
/*
|
|
* At this point, noone can insert into ep->rdllist besides
|
|
* us. The epoll_ctl() callers are locked out by us holding
|
|
* "mtx" and the poll callback will queue them in ep->ovflist.
|
|
*/
|
|
if (!(epi->event.events & EPOLLET) &&
|
|
(revents & epi->event.events))
|
|
list_add_tail(&epi->rdllink, &ep->rdllist);
|
|
}
|
|
error = 0;
|
|
|
|
errxit:
|
|
|
|
spin_lock_irqsave(&ep->lock, flags);
|
|
/*
|
|
* During the time we spent in the loop above, some other events
|
|
* might have been queued by the poll callback. We re-insert them
|
|
* inside the main ready-list here.
|
|
*/
|
|
for (nepi = ep->ovflist; (epi = nepi) != NULL;
|
|
nepi = epi->next, epi->next = EP_UNACTIVE_PTR) {
|
|
/*
|
|
* If the above loop quit with errors, the epoll item might still
|
|
* be linked to "txlist", and the list_splice() done below will
|
|
* take care of those cases.
|
|
*/
|
|
if (!ep_is_linked(&epi->rdllink))
|
|
list_add_tail(&epi->rdllink, &ep->rdllist);
|
|
}
|
|
/*
|
|
* We need to set back ep->ovflist to EP_UNACTIVE_PTR, so that after
|
|
* releasing the lock, events will be queued in the normal way inside
|
|
* ep->rdllist.
|
|
*/
|
|
ep->ovflist = EP_UNACTIVE_PTR;
|
|
|
|
/*
|
|
* In case of error in the event-send loop, or in case the number of
|
|
* ready events exceeds the userspace limit, we need to splice the
|
|
* "txlist" back inside ep->rdllist.
|
|
*/
|
|
list_splice(&txlist, &ep->rdllist);
|
|
|
|
if (!list_empty(&ep->rdllist)) {
|
|
/*
|
|
* Wake up (if active) both the eventpoll wait list and the ->poll()
|
|
* wait list (delayed after we release the lock).
|
|
*/
|
|
if (waitqueue_active(&ep->wq))
|
|
wake_up_locked(&ep->wq);
|
|
if (waitqueue_active(&ep->poll_wait))
|
|
pwake++;
|
|
}
|
|
spin_unlock_irqrestore(&ep->lock, flags);
|
|
|
|
mutex_unlock(&ep->mtx);
|
|
|
|
/* We have to call this outside the lock */
|
|
if (pwake)
|
|
ep_poll_safewake(&psw, &ep->poll_wait);
|
|
|
|
return eventcnt == 0 ? error: eventcnt;
|
|
}
|
|
|
|
static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events,
|
|
int maxevents, long timeout)
|
|
{
|
|
int res, eavail;
|
|
unsigned long flags;
|
|
long jtimeout;
|
|
wait_queue_t wait;
|
|
|
|
/*
|
|
* Calculate the timeout by checking for the "infinite" value ( -1 )
|
|
* and the overflow condition. The passed timeout is in milliseconds,
|
|
* that why (t * HZ) / 1000.
|
|
*/
|
|
jtimeout = (timeout < 0 || timeout >= EP_MAX_MSTIMEO) ?
|
|
MAX_SCHEDULE_TIMEOUT : (timeout * HZ + 999) / 1000;
|
|
|
|
retry:
|
|
spin_lock_irqsave(&ep->lock, flags);
|
|
|
|
res = 0;
|
|
if (list_empty(&ep->rdllist)) {
|
|
/*
|
|
* We don't have any available event to return to the caller.
|
|
* We need to sleep here, and we will be wake up by
|
|
* ep_poll_callback() when events will become available.
|
|
*/
|
|
init_waitqueue_entry(&wait, current);
|
|
wait.flags |= WQ_FLAG_EXCLUSIVE;
|
|
__add_wait_queue(&ep->wq, &wait);
|
|
|
|
for (;;) {
|
|
/*
|
|
* We don't want to sleep if the ep_poll_callback() sends us
|
|
* a wakeup in between. That's why we set the task state
|
|
* to TASK_INTERRUPTIBLE before doing the checks.
|
|
*/
|
|
set_current_state(TASK_INTERRUPTIBLE);
|
|
if (!list_empty(&ep->rdllist) || !jtimeout)
|
|
break;
|
|
if (signal_pending(current)) {
|
|
res = -EINTR;
|
|
break;
|
|
}
|
|
|
|
spin_unlock_irqrestore(&ep->lock, flags);
|
|
jtimeout = schedule_timeout(jtimeout);
|
|
spin_lock_irqsave(&ep->lock, flags);
|
|
}
|
|
__remove_wait_queue(&ep->wq, &wait);
|
|
|
|
set_current_state(TASK_RUNNING);
|
|
}
|
|
|
|
/* Is it worth to try to dig for events ? */
|
|
eavail = !list_empty(&ep->rdllist);
|
|
|
|
spin_unlock_irqrestore(&ep->lock, flags);
|
|
|
|
/*
|
|
* Try to transfer events to user space. In case we get 0 events and
|
|
* there's still timeout left over, we go trying again in search of
|
|
* more luck.
|
|
*/
|
|
if (!res && eavail &&
|
|
!(res = ep_send_events(ep, events, maxevents)) && jtimeout)
|
|
goto retry;
|
|
|
|
return res;
|
|
}
|
|
|
|
/*
|
|
* Open an eventpoll file descriptor.
|
|
*/
|
|
asmlinkage long sys_epoll_create1(int flags)
|
|
{
|
|
int error, fd = -1;
|
|
struct eventpoll *ep;
|
|
|
|
/* Check the EPOLL_* constant for consistency. */
|
|
BUILD_BUG_ON(EPOLL_CLOEXEC != O_CLOEXEC);
|
|
|
|
if (flags & ~EPOLL_CLOEXEC)
|
|
return -EINVAL;
|
|
|
|
DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_epoll_create(%d)\n",
|
|
current, flags));
|
|
|
|
/*
|
|
* Create the internal data structure ( "struct eventpoll" ).
|
|
*/
|
|
error = ep_alloc(&ep);
|
|
if (error < 0) {
|
|
fd = error;
|
|
goto error_return;
|
|
}
|
|
|
|
/*
|
|
* Creates all the items needed to setup an eventpoll file. That is,
|
|
* a file structure and a free file descriptor.
|
|
*/
|
|
fd = anon_inode_getfd("[eventpoll]", &eventpoll_fops, ep,
|
|
flags & O_CLOEXEC);
|
|
if (fd < 0)
|
|
ep_free(ep);
|
|
atomic_inc(&ep->user->epoll_devs);
|
|
|
|
error_return:
|
|
DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_epoll_create(%d) = %d\n",
|
|
current, flags, fd));
|
|
|
|
return fd;
|
|
}
|
|
|
|
asmlinkage long sys_epoll_create(int size)
|
|
{
|
|
if (size < 0)
|
|
return -EINVAL;
|
|
|
|
return sys_epoll_create1(0);
|
|
}
|
|
|
|
/*
|
|
* The following function implements the controller interface for
|
|
* the eventpoll file that enables the insertion/removal/change of
|
|
* file descriptors inside the interest set.
|
|
*/
|
|
asmlinkage long sys_epoll_ctl(int epfd, int op, int fd,
|
|
struct epoll_event __user *event)
|
|
{
|
|
int error;
|
|
struct file *file, *tfile;
|
|
struct eventpoll *ep;
|
|
struct epitem *epi;
|
|
struct epoll_event epds;
|
|
|
|
DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_epoll_ctl(%d, %d, %d, %p)\n",
|
|
current, epfd, op, fd, event));
|
|
|
|
error = -EFAULT;
|
|
if (ep_op_has_event(op) &&
|
|
copy_from_user(&epds, event, sizeof(struct epoll_event)))
|
|
goto error_return;
|
|
|
|
/* Get the "struct file *" for the eventpoll file */
|
|
error = -EBADF;
|
|
file = fget(epfd);
|
|
if (!file)
|
|
goto error_return;
|
|
|
|
/* Get the "struct file *" for the target file */
|
|
tfile = fget(fd);
|
|
if (!tfile)
|
|
goto error_fput;
|
|
|
|
/* The target file descriptor must support poll */
|
|
error = -EPERM;
|
|
if (!tfile->f_op || !tfile->f_op->poll)
|
|
goto error_tgt_fput;
|
|
|
|
/*
|
|
* We have to check that the file structure underneath the file descriptor
|
|
* the user passed to us _is_ an eventpoll file. And also we do not permit
|
|
* adding an epoll file descriptor inside itself.
|
|
*/
|
|
error = -EINVAL;
|
|
if (file == tfile || !is_file_epoll(file))
|
|
goto error_tgt_fput;
|
|
|
|
/*
|
|
* At this point it is safe to assume that the "private_data" contains
|
|
* our own data structure.
|
|
*/
|
|
ep = file->private_data;
|
|
|
|
mutex_lock(&ep->mtx);
|
|
|
|
/*
|
|
* Try to lookup the file inside our RB tree, Since we grabbed "mtx"
|
|
* above, we can be sure to be able to use the item looked up by
|
|
* ep_find() till we release the mutex.
|
|
*/
|
|
epi = ep_find(ep, tfile, fd);
|
|
|
|
error = -EINVAL;
|
|
switch (op) {
|
|
case EPOLL_CTL_ADD:
|
|
if (!epi) {
|
|
epds.events |= POLLERR | POLLHUP;
|
|
|
|
error = ep_insert(ep, &epds, tfile, fd);
|
|
} else
|
|
error = -EEXIST;
|
|
break;
|
|
case EPOLL_CTL_DEL:
|
|
if (epi)
|
|
error = ep_remove(ep, epi);
|
|
else
|
|
error = -ENOENT;
|
|
break;
|
|
case EPOLL_CTL_MOD:
|
|
if (epi) {
|
|
epds.events |= POLLERR | POLLHUP;
|
|
error = ep_modify(ep, epi, &epds);
|
|
} else
|
|
error = -ENOENT;
|
|
break;
|
|
}
|
|
mutex_unlock(&ep->mtx);
|
|
|
|
error_tgt_fput:
|
|
fput(tfile);
|
|
error_fput:
|
|
fput(file);
|
|
error_return:
|
|
DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_epoll_ctl(%d, %d, %d, %p) = %d\n",
|
|
current, epfd, op, fd, event, error));
|
|
|
|
return error;
|
|
}
|
|
|
|
/*
|
|
* Implement the event wait interface for the eventpoll file. It is the kernel
|
|
* part of the user space epoll_wait(2).
|
|
*/
|
|
asmlinkage long sys_epoll_wait(int epfd, struct epoll_event __user *events,
|
|
int maxevents, int timeout)
|
|
{
|
|
int error;
|
|
struct file *file;
|
|
struct eventpoll *ep;
|
|
|
|
DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_epoll_wait(%d, %p, %d, %d)\n",
|
|
current, epfd, events, maxevents, timeout));
|
|
|
|
/* The maximum number of event must be greater than zero */
|
|
if (maxevents <= 0 || maxevents > EP_MAX_EVENTS)
|
|
return -EINVAL;
|
|
|
|
/* Verify that the area passed by the user is writeable */
|
|
if (!access_ok(VERIFY_WRITE, events, maxevents * sizeof(struct epoll_event))) {
|
|
error = -EFAULT;
|
|
goto error_return;
|
|
}
|
|
|
|
/* Get the "struct file *" for the eventpoll file */
|
|
error = -EBADF;
|
|
file = fget(epfd);
|
|
if (!file)
|
|
goto error_return;
|
|
|
|
/*
|
|
* We have to check that the file structure underneath the fd
|
|
* the user passed to us _is_ an eventpoll file.
|
|
*/
|
|
error = -EINVAL;
|
|
if (!is_file_epoll(file))
|
|
goto error_fput;
|
|
|
|
/*
|
|
* At this point it is safe to assume that the "private_data" contains
|
|
* our own data structure.
|
|
*/
|
|
ep = file->private_data;
|
|
|
|
/* Time to fish for events ... */
|
|
error = ep_poll(ep, events, maxevents, timeout);
|
|
|
|
error_fput:
|
|
fput(file);
|
|
error_return:
|
|
DNPRINTK(3, (KERN_INFO "[%p] eventpoll: sys_epoll_wait(%d, %p, %d, %d) = %d\n",
|
|
current, epfd, events, maxevents, timeout, error));
|
|
|
|
return error;
|
|
}
|
|
|
|
#ifdef HAVE_SET_RESTORE_SIGMASK
|
|
|
|
/*
|
|
* Implement the event wait interface for the eventpoll file. It is the kernel
|
|
* part of the user space epoll_pwait(2).
|
|
*/
|
|
asmlinkage long sys_epoll_pwait(int epfd, struct epoll_event __user *events,
|
|
int maxevents, int timeout, const sigset_t __user *sigmask,
|
|
size_t sigsetsize)
|
|
{
|
|
int error;
|
|
sigset_t ksigmask, sigsaved;
|
|
|
|
/*
|
|
* If the caller wants a certain signal mask to be set during the wait,
|
|
* we apply it here.
|
|
*/
|
|
if (sigmask) {
|
|
if (sigsetsize != sizeof(sigset_t))
|
|
return -EINVAL;
|
|
if (copy_from_user(&ksigmask, sigmask, sizeof(ksigmask)))
|
|
return -EFAULT;
|
|
sigdelsetmask(&ksigmask, sigmask(SIGKILL) | sigmask(SIGSTOP));
|
|
sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved);
|
|
}
|
|
|
|
error = sys_epoll_wait(epfd, events, maxevents, timeout);
|
|
|
|
/*
|
|
* If we changed the signal mask, we need to restore the original one.
|
|
* In case we've got a signal while waiting, we do not restore the
|
|
* signal mask yet, and we allow do_signal() to deliver the signal on
|
|
* the way back to userspace, before the signal mask is restored.
|
|
*/
|
|
if (sigmask) {
|
|
if (error == -EINTR) {
|
|
memcpy(¤t->saved_sigmask, &sigsaved,
|
|
sizeof(sigsaved));
|
|
set_restore_sigmask();
|
|
} else
|
|
sigprocmask(SIG_SETMASK, &sigsaved, NULL);
|
|
}
|
|
|
|
return error;
|
|
}
|
|
|
|
#endif /* HAVE_SET_RESTORE_SIGMASK */
|
|
|
|
static int __init eventpoll_init(void)
|
|
{
|
|
struct sysinfo si;
|
|
|
|
si_meminfo(&si);
|
|
max_user_instances = 128;
|
|
max_user_watches = (((si.totalram - si.totalhigh) / 32) << PAGE_SHIFT) /
|
|
EP_ITEM_COST;
|
|
|
|
/* Initialize the structure used to perform safe poll wait head wake ups */
|
|
ep_poll_safewake_init(&psw);
|
|
|
|
/* Allocates slab cache used to allocate "struct epitem" items */
|
|
epi_cache = kmem_cache_create("eventpoll_epi", sizeof(struct epitem),
|
|
0, SLAB_HWCACHE_ALIGN|EPI_SLAB_DEBUG|SLAB_PANIC,
|
|
NULL);
|
|
|
|
/* Allocates slab cache used to allocate "struct eppoll_entry" */
|
|
pwq_cache = kmem_cache_create("eventpoll_pwq",
|
|
sizeof(struct eppoll_entry), 0,
|
|
EPI_SLAB_DEBUG|SLAB_PANIC, NULL);
|
|
|
|
return 0;
|
|
}
|
|
fs_initcall(eventpoll_init);
|