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| author | Eric W. Biederman <ebiederm@xmission.com> | 2006-10-02 02:17:13 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-10-02 07:57:13 -0700 |
| commit | 81af8d67d4fc35b1ee6e0feb1f1b34b3a33eeb44 (patch) | |
| tree | 0217dde7d28427e9b6ac587fd4edb9fb1f8f11b4 | |
| parent | 5feb8f5f8403d8874a04aac443692dfe83bd63d2 (diff) | |
| download | talos-op-linux-81af8d67d4fc35b1ee6e0feb1f1b34b3a33eeb44.tar.gz talos-op-linux-81af8d67d4fc35b1ee6e0feb1f1b34b3a33eeb44.zip | |
[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.c | 16 | ||||
| -rw-r--r-- | drivers/char/vt_ioctl.c | 9 | ||||
| -rw-r--r-- | include/linux/vt_kern.h | 7 |
3 files changed, 25 insertions, 7 deletions
diff --git a/drivers/char/keyboard.c b/drivers/char/keyboard.c index 3e90aac37510..99fb070fdbf8 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 a53e382cc107..dc408af165ab 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 1009d3fe1fc2..37a1a41f5b65 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 */ |
