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Date: Mon, 02 Jan 2012 21:22:54 +0400
From: Konstantin Khlebnikov <khlebnikov@...nvz.org>
To: Greg Kroah-Hartman <gregkh@...e.de>
Cc: linux-kernel@...r.kernel.org
Subject: [PATCH 1/2] tty: move pty count limiting into devpts
Let's move this stuff to the better place, where we can account pty right in
tty-indexes managing code.
Signed-off-by: Konstantin Khlebnikov <khlebnikov@...nvz.org>
---
drivers/tty/pty.c | 63 -----------------------------------------------------
fs/devpts/inode.c | 53 ++++++++++++++++++++++++++++++++++++++++++++-
2 files changed, 52 insertions(+), 64 deletions(-)
diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c
index d2bf3c1..33f7e18 100644
--- a/drivers/tty/pty.c
+++ b/drivers/tty/pty.c
@@ -21,7 +21,6 @@
#include <linux/major.h>
#include <linux/mm.h>
#include <linux/init.h>
-#include <linux/sysctl.h>
#include <linux/device.h>
#include <linux/uaccess.h>
#include <linux/bitops.h>
@@ -439,66 +438,9 @@ static inline void legacy_pty_init(void) { }
/* Unix98 devices */
#ifdef CONFIG_UNIX98_PTYS
-/*
- * sysctl support for setting limits on the number of Unix98 ptys allocated.
- * Otherwise one can eat up all kernel memory by opening /dev/ptmx repeatedly.
- */
-int pty_limit = NR_UNIX98_PTY_DEFAULT;
-static int pty_limit_min;
-static int pty_limit_max = NR_UNIX98_PTY_MAX;
-static int tty_count;
-static int pty_count;
-
-static inline void pty_inc_count(void)
-{
- pty_count = (++tty_count) / 2;
-}
-
-static inline void pty_dec_count(void)
-{
- pty_count = (--tty_count) / 2;
-}
static struct cdev ptmx_cdev;
-static struct ctl_table pty_table[] = {
- {
- .procname = "max",
- .maxlen = sizeof(int),
- .mode = 0644,
- .data = &pty_limit,
- .proc_handler = proc_dointvec_minmax,
- .extra1 = &pty_limit_min,
- .extra2 = &pty_limit_max,
- }, {
- .procname = "nr",
- .maxlen = sizeof(int),
- .mode = 0444,
- .data = &pty_count,
- .proc_handler = proc_dointvec,
- },
- {}
-};
-
-static struct ctl_table pty_kern_table[] = {
- {
- .procname = "pty",
- .mode = 0555,
- .child = pty_table,
- },
- {}
-};
-
-static struct ctl_table pty_root_table[] = {
- {
- .procname = "kernel",
- .mode = 0555,
- .child = pty_kern_table,
- },
- {}
-};
-
-
static int pty_unix98_ioctl(struct tty_struct *tty,
unsigned int cmd, unsigned long arg)
{
@@ -598,8 +540,6 @@ static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty)
*/
tty_driver_kref_get(driver);
tty->count++;
- pty_inc_count(); /* tty */
- pty_inc_count(); /* tty->link */
return 0;
err_free_mem:
deinitialize_tty_struct(o_tty);
@@ -613,7 +553,6 @@ err_free_tty:
static void pty_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
{
- pty_dec_count();
}
static const struct tty_operations ptm_unix98_ops = {
@@ -768,8 +707,6 @@ static void __init unix98_pty_init(void)
if (tty_register_driver(pts_driver))
panic("Couldn't register Unix98 pts driver");
- register_sysctl_table(pty_root_table);
-
/* Now create the /dev/ptmx special device */
tty_default_fops(&ptmx_fops);
ptmx_fops.open = ptmx_open;
diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c
index d5d5297..dd37e85 100644
--- a/fs/devpts/inode.c
+++ b/fs/devpts/inode.c
@@ -36,7 +36,52 @@
#define DEVPTS_DEFAULT_PTMX_MODE 0000
#define PTMX_MINOR 2
-extern int pty_limit; /* Config limit on Unix98 ptys */
+/*
+ * sysctl support for setting limits on the number of Unix98 ptys allocated.
+ * Otherwise one can eat up all kernel memory by opening /dev/ptmx repeatedly.
+ */
+static int pty_limit = NR_UNIX98_PTY_DEFAULT;
+static int pty_limit_min;
+static int pty_limit_max = NR_UNIX98_PTY_MAX;
+static int pty_count;
+
+static struct ctl_table pty_table[] = {
+ {
+ .procname = "max",
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .data = &pty_limit,
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = &pty_limit_min,
+ .extra2 = &pty_limit_max,
+ }, {
+ .procname = "nr",
+ .maxlen = sizeof(int),
+ .mode = 0444,
+ .data = &pty_count,
+ .proc_handler = proc_dointvec,
+ },
+ {}
+};
+
+static struct ctl_table pty_kern_table[] = {
+ {
+ .procname = "pty",
+ .mode = 0555,
+ .child = pty_table,
+ },
+ {}
+};
+
+static struct ctl_table pty_root_table[] = {
+ {
+ .procname = "kernel",
+ .mode = 0555,
+ .child = pty_kern_table,
+ },
+ {}
+};
+
static DEFINE_MUTEX(allocated_ptys_lock);
static struct vfsmount *devpts_mnt;
@@ -453,6 +498,7 @@ retry:
mutex_unlock(&allocated_ptys_lock);
return -EIO;
}
+ pty_count++;
mutex_unlock(&allocated_ptys_lock);
return index;
}
@@ -464,6 +510,7 @@ void devpts_kill_index(struct inode *ptmx_inode, int idx)
mutex_lock(&allocated_ptys_lock);
ida_remove(&fsi->allocated_ptys, idx);
+ pty_count--;
mutex_unlock(&allocated_ptys_lock);
}
@@ -560,11 +607,15 @@ void devpts_pty_kill(struct tty_struct *tty)
static int __init init_devpts_fs(void)
{
int err = register_filesystem(&devpts_fs_type);
+ struct ctl_table_header *table;
+
if (!err) {
+ table = register_sysctl_table(pty_root_table);
devpts_mnt = kern_mount(&devpts_fs_type);
if (IS_ERR(devpts_mnt)) {
err = PTR_ERR(devpts_mnt);
unregister_filesystem(&devpts_fs_type);
+ unregister_sysctl_table(table);
}
}
return err;
--
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