linux-stable/fs/proc/proc_tty.c

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License cleanup: add SPDX GPL-2.0 license identifier to files with no license Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-01 14:07:57 +00:00
// SPDX-License-Identifier: GPL-2.0
/*
* proc_tty.c -- handles /proc/tty
*
* Copyright 1997, Theodore Ts'o
*/
#include <linux/uaccess.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/time.h>
#include <linux/proc_fs.h>
#include <linux/stat.h>
#include <linux/tty.h>
#include <linux/seq_file.h>
#include <linux/bitops.h>
tty fix oops when rmmod 8250 After rmmod 8250.ko tty_kref_put starts kwork (release_one_tty) to release proc interface oops when accessing driver->driver_name in proc_tty_unregister_driver Use jprobe, found driver->driver_name point to 8250.ko static static struct uart_driver serial8250_reg .driver_name= serial, Use name in proc_dir_entry instead of driver->driver_name to fix oops test on linux 4.1.12: BUG: unable to handle kernel paging request at ffffffffa01979de IP: [<ffffffff81310f40>] strchr+0x0/0x30 PGD 1a0d067 PUD 1a0e063 PMD 851c1f067 PTE 0 Oops: 0000 [#1] PREEMPT SMP Modules linked in: ... ... [last unloaded: 8250] CPU: 7 PID: 116 Comm: kworker/7:1 Tainted: G O 4.1.12 #1 Hardware name: Insyde RiverForest/Type2 - Board Product Name1, BIOS NE5KV904 12/21/2015 Workqueue: events release_one_tty task: ffff88085b684960 ti: ffff880852884000 task.ti: ffff880852884000 RIP: 0010:[<ffffffff81310f40>] [<ffffffff81310f40>] strchr+0x0/0x30 RSP: 0018:ffff880852887c90 EFLAGS: 00010282 RAX: ffffffff81a5eca0 RBX: ffffffffa01979de RCX: 0000000000000004 RDX: ffff880852887d10 RSI: 000000000000002f RDI: ffffffffa01979de RBP: ffff880852887cd8 R08: 0000000000000000 R09: ffff88085f5d94d0 R10: 0000000000000195 R11: 0000000000000000 R12: ffffffffa01979de R13: ffff880852887d00 R14: ffffffffa01979de R15: ffff88085f02e840 FS: 0000000000000000(0000) GS:ffff88085f5c0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffa01979de CR3: 0000000001a0c000 CR4: 00000000001406e0 Stack: ffffffff812349b1 ffff880852887cb8 ffff880852887d10 ffff88085f5cd6c2 ffff880852800a80 ffffffffa01979de ffff880852800a84 0000000000000010 ffff88085bb28bd8 ffff880852887d38 ffffffff812354f0 ffff880852887d08 Call Trace: [<ffffffff812349b1>] ? __xlate_proc_name+0x71/0xd0 [<ffffffff812354f0>] remove_proc_entry+0x40/0x180 [<ffffffff815f6811>] ? _raw_spin_lock_irqsave+0x41/0x60 [<ffffffff813be520>] ? destruct_tty_driver+0x60/0xe0 [<ffffffff81237c68>] proc_tty_unregister_driver+0x28/0x40 [<ffffffff813be548>] destruct_tty_driver+0x88/0xe0 [<ffffffff813be5bd>] tty_driver_kref_put+0x1d/0x20 [<ffffffff813becca>] release_one_tty+0x5a/0xd0 [<ffffffff81074159>] process_one_work+0x139/0x420 [<ffffffff810745a1>] worker_thread+0x121/0x450 [<ffffffff81074480>] ? process_scheduled_works+0x40/0x40 [<ffffffff8107a16c>] kthread+0xec/0x110 [<ffffffff81080000>] ? tg_rt_schedulable+0x210/0x220 [<ffffffff8107a080>] ? kthread_freezable_should_stop+0x80/0x80 [<ffffffff815f7292>] ret_from_fork+0x42/0x70 [<ffffffff8107a080>] ? kthread_freezable_should_stop+0x80/0x80 Signed-off-by: nixiaoming <nixiaoming@huawei.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-09-15 09:45:56 +00:00
#include "internal.h"
/*
* The /proc/tty directory inodes...
*/
static struct proc_dir_entry *proc_tty_driver;
/*
* This is the handler for /proc/tty/drivers
*/
static void show_tty_range(struct seq_file *m, struct tty_driver *p,
dev_t from, int num)
{
seq_printf(m, "%-20s ", p->driver_name ? p->driver_name : "unknown");
seq_printf(m, "/dev/%-8s ", p->name);
if (p->num > 1) {
seq_printf(m, "%3d %d-%d ", MAJOR(from), MINOR(from),
MINOR(from) + num - 1);
} else {
seq_printf(m, "%3d %7d ", MAJOR(from), MINOR(from));
}
switch (p->type) {
case TTY_DRIVER_TYPE_SYSTEM:
seq_puts(m, "system");
if (p->subtype == SYSTEM_TYPE_TTY)
seq_puts(m, ":/dev/tty");
else if (p->subtype == SYSTEM_TYPE_SYSCONS)
seq_puts(m, ":console");
else if (p->subtype == SYSTEM_TYPE_CONSOLE)
seq_puts(m, ":vtmaster");
break;
case TTY_DRIVER_TYPE_CONSOLE:
seq_puts(m, "console");
break;
case TTY_DRIVER_TYPE_SERIAL:
seq_puts(m, "serial");
break;
case TTY_DRIVER_TYPE_PTY:
if (p->subtype == PTY_TYPE_MASTER)
seq_puts(m, "pty:master");
else if (p->subtype == PTY_TYPE_SLAVE)
seq_puts(m, "pty:slave");
else
seq_puts(m, "pty");
break;
default:
seq_printf(m, "type:%d.%d", p->type, p->subtype);
}
seq_putc(m, '\n');
}
static int show_tty_driver(struct seq_file *m, void *v)
{
struct tty_driver *p = list_entry(v, struct tty_driver, tty_drivers);
dev_t from = MKDEV(p->major, p->minor_start);
dev_t to = from + p->num;
if (&p->tty_drivers == tty_drivers.next) {
/* pseudo-drivers first */
seq_printf(m, "%-20s /dev/%-8s ", "/dev/tty", "tty");
seq_printf(m, "%3d %7d ", TTYAUX_MAJOR, 0);
seq_puts(m, "system:/dev/tty\n");
seq_printf(m, "%-20s /dev/%-8s ", "/dev/console", "console");
seq_printf(m, "%3d %7d ", TTYAUX_MAJOR, 1);
seq_puts(m, "system:console\n");
#ifdef CONFIG_UNIX98_PTYS
seq_printf(m, "%-20s /dev/%-8s ", "/dev/ptmx", "ptmx");
seq_printf(m, "%3d %7d ", TTYAUX_MAJOR, 2);
seq_puts(m, "system\n");
#endif
#ifdef CONFIG_VT
seq_printf(m, "%-20s /dev/%-8s ", "/dev/vc/0", "vc/0");
seq_printf(m, "%3d %7d ", TTY_MAJOR, 0);
seq_puts(m, "system:vtmaster\n");
#endif
}
while (MAJOR(from) < MAJOR(to)) {
dev_t next = MKDEV(MAJOR(from)+1, 0);
show_tty_range(m, p, from, next - from);
from = next;
}
if (from != to)
show_tty_range(m, p, from, to - from);
return 0;
}
/* iterator */
static void *t_start(struct seq_file *m, loff_t *pos)
{
Protect tty drivers list with tty_mutex Additions and removal from tty_drivers list were just done as well as iterating on it for /proc/tty/drivers generation. testing: modprobe/rmmod loop of simple module which does nothing but tty_register_driver() vs cat /proc/tty/drivers loop BUG: unable to handle kernel paging request at virtual address 6b6b6b6b printing eip: c01cefa7 *pde = 00000000 Oops: 0000 [#1] PREEMPT last sysfs file: devices/pci0000:00/0000:00:1d.7/usb5/5-0:1.0/bInterfaceProtocol Modules linked in: ohci_hcd af_packet e1000 ehci_hcd uhci_hcd usbcore xfs CPU: 0 EIP: 0060:[<c01cefa7>] Not tainted VLI EFLAGS: 00010297 (2.6.21-rc4-mm1 #4) EIP is at vsnprintf+0x3a4/0x5fc eax: 6b6b6b6b ebx: f6cb50f2 ecx: 6b6b6b6b edx: fffffffe esi: c0354700 edi: f6cb6000 ebp: 6b6b6b6b esp: f31f5e68 ds: 007b es: 007b fs: 00d8 gs: 0033 ss: 0068 Process cat (pid: 31864, ti=f31f4000 task=c1998030 task.ti=f31f4000) Stack: 00000000 c0103f20 c013003a c0103f20 00000000 f6cb50da 0000000a 00000f0e f6cb50f2 00000010 00000014 ffffffff ffffffff 00000007 c0354753 f6cb50f2 f73e39dc f73e39dc 00000001 c0175416 f31f5ed8 f31f5ed4 0ee00000 f32090bc Call Trace: [<c0103f20>] restore_nocheck+0x12/0x15 [<c013003a>] mark_held_locks+0x6d/0x86 [<c0103f20>] restore_nocheck+0x12/0x15 [<c0175416>] seq_printf+0x2e/0x52 [<c0192895>] show_tty_range+0x35/0x1f3 [<c0175416>] seq_printf+0x2e/0x52 [<c0192add>] show_tty_driver+0x8a/0x1d9 [<c01758f6>] seq_read+0x70/0x2ba [<c0175886>] seq_read+0x0/0x2ba [<c018d8e6>] proc_reg_read+0x63/0x9f [<c015e764>] vfs_read+0x7d/0xb5 [<c018d883>] proc_reg_read+0x0/0x9f [<c015eab1>] sys_read+0x41/0x6a [<c0103e4e>] sysenter_past_esp+0x5f/0x99 ======================= Code: 00 8b 4d 04 e9 44 ff ff ff 8d 4d 04 89 4c 24 50 8b 6d 00 81 fd ff 0f 00 00 b8 a4 c1 35 c0 0f 46 e8 8b 54 24 2c 89 e9 89 c8 eb 06 <80> 38 00 74 07 40 4a 83 fa ff 75 f4 29 c8 89 c6 8b 44 24 28 89 EIP: [<c01cefa7>] vsnprintf+0x3a4/0x5fc SS:ESP 0068:f31f5e68 Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-08 07:27:12 +00:00
mutex_lock(&tty_mutex);
return seq_list_start(&tty_drivers, *pos);
}
static void *t_next(struct seq_file *m, void *v, loff_t *pos)
{
return seq_list_next(v, &tty_drivers, pos);
}
static void t_stop(struct seq_file *m, void *v)
{
Protect tty drivers list with tty_mutex Additions and removal from tty_drivers list were just done as well as iterating on it for /proc/tty/drivers generation. testing: modprobe/rmmod loop of simple module which does nothing but tty_register_driver() vs cat /proc/tty/drivers loop BUG: unable to handle kernel paging request at virtual address 6b6b6b6b printing eip: c01cefa7 *pde = 00000000 Oops: 0000 [#1] PREEMPT last sysfs file: devices/pci0000:00/0000:00:1d.7/usb5/5-0:1.0/bInterfaceProtocol Modules linked in: ohci_hcd af_packet e1000 ehci_hcd uhci_hcd usbcore xfs CPU: 0 EIP: 0060:[<c01cefa7>] Not tainted VLI EFLAGS: 00010297 (2.6.21-rc4-mm1 #4) EIP is at vsnprintf+0x3a4/0x5fc eax: 6b6b6b6b ebx: f6cb50f2 ecx: 6b6b6b6b edx: fffffffe esi: c0354700 edi: f6cb6000 ebp: 6b6b6b6b esp: f31f5e68 ds: 007b es: 007b fs: 00d8 gs: 0033 ss: 0068 Process cat (pid: 31864, ti=f31f4000 task=c1998030 task.ti=f31f4000) Stack: 00000000 c0103f20 c013003a c0103f20 00000000 f6cb50da 0000000a 00000f0e f6cb50f2 00000010 00000014 ffffffff ffffffff 00000007 c0354753 f6cb50f2 f73e39dc f73e39dc 00000001 c0175416 f31f5ed8 f31f5ed4 0ee00000 f32090bc Call Trace: [<c0103f20>] restore_nocheck+0x12/0x15 [<c013003a>] mark_held_locks+0x6d/0x86 [<c0103f20>] restore_nocheck+0x12/0x15 [<c0175416>] seq_printf+0x2e/0x52 [<c0192895>] show_tty_range+0x35/0x1f3 [<c0175416>] seq_printf+0x2e/0x52 [<c0192add>] show_tty_driver+0x8a/0x1d9 [<c01758f6>] seq_read+0x70/0x2ba [<c0175886>] seq_read+0x0/0x2ba [<c018d8e6>] proc_reg_read+0x63/0x9f [<c015e764>] vfs_read+0x7d/0xb5 [<c018d883>] proc_reg_read+0x0/0x9f [<c015eab1>] sys_read+0x41/0x6a [<c0103e4e>] sysenter_past_esp+0x5f/0x99 ======================= Code: 00 8b 4d 04 e9 44 ff ff ff 8d 4d 04 89 4c 24 50 8b 6d 00 81 fd ff 0f 00 00 b8 a4 c1 35 c0 0f 46 e8 8b 54 24 2c 89 e9 89 c8 eb 06 <80> 38 00 74 07 40 4a 83 fa ff 75 f4 29 c8 89 c6 8b 44 24 28 89 EIP: [<c01cefa7>] vsnprintf+0x3a4/0x5fc SS:ESP 0068:f31f5e68 Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-08 07:27:12 +00:00
mutex_unlock(&tty_mutex);
}
static const struct seq_operations tty_drivers_op = {
.start = t_start,
.next = t_next,
.stop = t_stop,
.show = show_tty_driver
};
/*
* This function is called by tty_register_driver() to handle
* registering the driver's /proc handler into /proc/tty/driver/<foo>
*/
void proc_tty_register_driver(struct tty_driver *driver)
{
struct proc_dir_entry *ent;
if (!driver->driver_name || driver->proc_entry ||
!driver->ops->proc_show)
return;
ent = proc_create_single_data(driver->driver_name, 0, proc_tty_driver,
driver->ops->proc_show, driver);
driver->proc_entry = ent;
}
/*
* This function is called by tty_unregister_driver()
*/
void proc_tty_unregister_driver(struct tty_driver *driver)
{
struct proc_dir_entry *ent;
ent = driver->proc_entry;
if (!ent)
return;
tty fix oops when rmmod 8250 After rmmod 8250.ko tty_kref_put starts kwork (release_one_tty) to release proc interface oops when accessing driver->driver_name in proc_tty_unregister_driver Use jprobe, found driver->driver_name point to 8250.ko static static struct uart_driver serial8250_reg .driver_name= serial, Use name in proc_dir_entry instead of driver->driver_name to fix oops test on linux 4.1.12: BUG: unable to handle kernel paging request at ffffffffa01979de IP: [<ffffffff81310f40>] strchr+0x0/0x30 PGD 1a0d067 PUD 1a0e063 PMD 851c1f067 PTE 0 Oops: 0000 [#1] PREEMPT SMP Modules linked in: ... ... [last unloaded: 8250] CPU: 7 PID: 116 Comm: kworker/7:1 Tainted: G O 4.1.12 #1 Hardware name: Insyde RiverForest/Type2 - Board Product Name1, BIOS NE5KV904 12/21/2015 Workqueue: events release_one_tty task: ffff88085b684960 ti: ffff880852884000 task.ti: ffff880852884000 RIP: 0010:[<ffffffff81310f40>] [<ffffffff81310f40>] strchr+0x0/0x30 RSP: 0018:ffff880852887c90 EFLAGS: 00010282 RAX: ffffffff81a5eca0 RBX: ffffffffa01979de RCX: 0000000000000004 RDX: ffff880852887d10 RSI: 000000000000002f RDI: ffffffffa01979de RBP: ffff880852887cd8 R08: 0000000000000000 R09: ffff88085f5d94d0 R10: 0000000000000195 R11: 0000000000000000 R12: ffffffffa01979de R13: ffff880852887d00 R14: ffffffffa01979de R15: ffff88085f02e840 FS: 0000000000000000(0000) GS:ffff88085f5c0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffa01979de CR3: 0000000001a0c000 CR4: 00000000001406e0 Stack: ffffffff812349b1 ffff880852887cb8 ffff880852887d10 ffff88085f5cd6c2 ffff880852800a80 ffffffffa01979de ffff880852800a84 0000000000000010 ffff88085bb28bd8 ffff880852887d38 ffffffff812354f0 ffff880852887d08 Call Trace: [<ffffffff812349b1>] ? __xlate_proc_name+0x71/0xd0 [<ffffffff812354f0>] remove_proc_entry+0x40/0x180 [<ffffffff815f6811>] ? _raw_spin_lock_irqsave+0x41/0x60 [<ffffffff813be520>] ? destruct_tty_driver+0x60/0xe0 [<ffffffff81237c68>] proc_tty_unregister_driver+0x28/0x40 [<ffffffff813be548>] destruct_tty_driver+0x88/0xe0 [<ffffffff813be5bd>] tty_driver_kref_put+0x1d/0x20 [<ffffffff813becca>] release_one_tty+0x5a/0xd0 [<ffffffff81074159>] process_one_work+0x139/0x420 [<ffffffff810745a1>] worker_thread+0x121/0x450 [<ffffffff81074480>] ? process_scheduled_works+0x40/0x40 [<ffffffff8107a16c>] kthread+0xec/0x110 [<ffffffff81080000>] ? tg_rt_schedulable+0x210/0x220 [<ffffffff8107a080>] ? kthread_freezable_should_stop+0x80/0x80 [<ffffffff815f7292>] ret_from_fork+0x42/0x70 [<ffffffff8107a080>] ? kthread_freezable_should_stop+0x80/0x80 Signed-off-by: nixiaoming <nixiaoming@huawei.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-09-15 09:45:56 +00:00
remove_proc_entry(ent->name, proc_tty_driver);
driver->proc_entry = NULL;
}
/*
* Called by proc_root_init() to initialize the /proc/tty subtree
*/
void __init proc_tty_init(void)
{
if (!proc_mkdir("tty", NULL))
return;
proc_mkdir("tty/ldisc", NULL); /* Preserved: it's userspace visible */
/*
* /proc/tty/driver/serial reveals the exact character counts for
* serial links which is just too easy to abuse for inferring
* password lengths and inter-keystroke timings during password
* entry.
*/
proc_tty_driver = proc_mkdir_mode("tty/driver", S_IRUSR|S_IXUSR, NULL);
proc_create_seq("tty/ldiscs", 0, NULL, &tty_ldiscs_seq_ops);
proc_create_seq("tty/drivers", 0, NULL, &tty_drivers_op);
}