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authorEric W. Biederman <ebiederm@xmission.com>2006-10-02 02:17:13 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2006-10-02 07:57:13 -0700
commit81af8d67d4fc35b1ee6e0feb1f1b34b3a33eeb44 (patch)
tree0217dde7d28427e9b6ac587fd4edb9fb1f8f11b4
parent5feb8f5f8403d8874a04aac443692dfe83bd63d2 (diff)
[PATCH] vt: rework the console spawning variables
This is such a rare path it took me a while to figure out how to test this after soring out the locking. This patch does several things. - The variables used are moved into a structure and declared in vt_kern.h - A spinlock is added so we don't have SMP races updating the values. - Instead of raw pid_t value a struct_pid is used to guard against pid wrap around issues, if the daemon to spawn a new console dies. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--drivers/char/keyboard.c16
-rw-r--r--drivers/char/vt_ioctl.c9
-rw-r--r--include/linux/vt_kern.h7
3 files changed, 25 insertions, 7 deletions
diff --git a/drivers/char/keyboard.c b/drivers/char/keyboard.c
index 3e90aac3751..99fb070fdbf 100644
--- a/drivers/char/keyboard.c
+++ b/drivers/char/keyboard.c
@@ -108,7 +108,11 @@ const int NR_TYPES = ARRAY_SIZE(max_vals);
struct kbd_struct kbd_table[MAX_NR_CONSOLES];
static struct kbd_struct *kbd = kbd_table;
-int spawnpid, spawnsig;
+struct vt_spawn_console vt_spawn_con = {
+ .lock = SPIN_LOCK_UNLOCKED,
+ .pid = NULL,
+ .sig = 0,
+};
/*
* Variables exported for vt.c
@@ -578,9 +582,13 @@ static void fn_compose(struct vc_data *vc, struct pt_regs *regs)
static void fn_spawn_con(struct vc_data *vc, struct pt_regs *regs)
{
- if (spawnpid)
- if (kill_proc(spawnpid, spawnsig, 1))
- spawnpid = 0;
+ spin_lock(&vt_spawn_con.lock);
+ if (vt_spawn_con.pid)
+ if (kill_pid(vt_spawn_con.pid, vt_spawn_con.sig, 1)) {
+ put_pid(vt_spawn_con.pid);
+ vt_spawn_con.pid = NULL;
+ }
+ spin_unlock(&vt_spawn_con.lock);
}
static void fn_SAK(struct vc_data *vc, struct pt_regs *regs)
diff --git a/drivers/char/vt_ioctl.c b/drivers/char/vt_ioctl.c
index a53e382cc10..dc408af165a 100644
--- a/drivers/char/vt_ioctl.c
+++ b/drivers/char/vt_ioctl.c
@@ -645,13 +645,16 @@ int vt_ioctl(struct tty_struct *tty, struct file * file,
*/
case KDSIGACCEPT:
{
- extern int spawnpid, spawnsig;
if (!perm || !capable(CAP_KILL))
return -EPERM;
if (!valid_signal(arg) || arg < 1 || arg == SIGKILL)
return -EINVAL;
- spawnpid = current->pid;
- spawnsig = arg;
+
+ spin_lock_irq(&vt_spawn_con.lock);
+ put_pid(vt_spawn_con.pid);
+ vt_spawn_con.pid = get_pid(task_pid(current));
+ vt_spawn_con.sig = arg;
+ spin_unlock_irq(&vt_spawn_con.lock);
return 0;
}
diff --git a/include/linux/vt_kern.h b/include/linux/vt_kern.h
index 1009d3fe1fc..37a1a41f5b6 100644
--- a/include/linux/vt_kern.h
+++ b/include/linux/vt_kern.h
@@ -84,4 +84,11 @@ void reset_vc(struct vc_data *vc);
extern char con_buf[CON_BUF_SIZE];
extern struct semaphore con_buf_sem;
+struct vt_spawn_console {
+ spinlock_t lock;
+ struct pid *pid;
+ int sig;
+};
+extern struct vt_spawn_console vt_spawn_con;
+
#endif /* _VT_KERN_H */