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ieee1394: raw1394: replace BKL by local mutex, make ioctl() and mmap() thread-safe

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This removes the last usage of the Big Kernel Lock from the ieee1394
stack, i.e. from raw1394's (unlocked_)ioctl and compat_ioctl.

The ioctl()s don't need to take the BKL, but they need to be serialized
per struct file *.  In particular, accesses to ->iso_state need to be
serial.  We simply use a blocking mutex for this purpose because
libraw1394 does not use O_NONBLOCK.  In practice, there is no lock
contention anyway because most if not all libraw1394 clients use a
libraw1394 handle only in a single thread.

mmap() also accesses ->iso_state.  Until now this was unprotected
against concurrent changes by ioctls.  Fix this bug while we are at it.

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
This commit is contained in:
Stefan Richter 2008-08-16 00:11:48 +02:00
parent ed6ffd0808
commit 10963ea1bd
2 changed files with 18 additions and 6 deletions
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1
drivers/ieee1394/raw1394-private.h
View file

@ -22,6 +22,7 @@ enum raw1394_iso_state { RAW1394_ISO_INACTIVE = 0,
struct file_info {
struct list_head list;
struct mutex state_mutex;
enum { opened, initialized, connected } state;
unsigned int protocol_version;

23
drivers/ieee1394/raw1394.c
View file

@ -34,6 +34,7 @@
#include <linux/fs.h>
#include <linux/poll.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/vmalloc.h>
@ -2541,11 +2542,18 @@ static int raw1394_read_cycle_timer(struct file_info *fi, void __user * uaddr)
static int raw1394_mmap(struct file *file, struct vm_area_struct *vma)
{
struct file_info *fi = file->private_data;
int ret;
mutex_lock(&fi->state_mutex);
if (fi->iso_state == RAW1394_ISO_INACTIVE)
return -EINVAL;
ret = -EINVAL;
else
ret = dma_region_mmap(&fi->iso_handle->data_buf, file, vma);
return dma_region_mmap(&fi->iso_handle->data_buf, file, vma);
mutex_unlock(&fi->state_mutex);
return ret;
}
/* ioctl is only used for rawiso operations */
@ -2659,10 +2667,12 @@ static long do_raw1394_ioctl(struct file *file, unsigned int cmd,
static long raw1394_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
struct file_info *fi = file->private_data;
long ret;
lock_kernel();
mutex_lock(&fi->state_mutex);
ret = do_raw1394_ioctl(file, cmd, arg);
unlock_kernel();
mutex_unlock(&fi->state_mutex);
return ret;
}
@ -2724,7 +2734,7 @@ static long raw1394_compat_ioctl(struct file *file,
void __user *argp = (void __user *)arg;
long err;
lock_kernel();
mutex_lock(&fi->state_mutex);
switch (cmd) {
/* These requests have same format as long as 'int' has same size. */
case RAW1394_IOC_ISO_RECV_INIT:
@ -2757,7 +2767,7 @@ static long raw1394_compat_ioctl(struct file *file,
err = -EINVAL;
break;
}
unlock_kernel();
mutex_unlock(&fi->state_mutex);
return err;
}
@ -2791,6 +2801,7 @@ static int raw1394_open(struct inode *inode, struct file *file)
fi->notification = (u8) RAW1394_NOTIFY_ON; /* busreset notification */
INIT_LIST_HEAD(&fi->list);
mutex_init(&fi->state_mutex);
fi->state = opened;
INIT_LIST_HEAD(&fi->req_pending);
INIT_LIST_HEAD(&fi->req_complete);