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signal: introduce kernel_signal_stop() to fix jffs2_garbage_collect_thread()

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jffs2_garbage_collect_thread() can race with SIGCONT and sleep in
TASK_STOPPED state after it was already sent. Add the new helper,
kernel_signal_stop(), which does this correctly.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Tejun Heo <tj@kernel.org>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Felipe Balbi <balbi@ti.com>
Cc: Markus Pargmann <mpa@pengutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Oleg Nesterov 2015-11-06 16:32:25 -08:00 committed by Linus Torvalds
parent be0e6f290f
commit 9a13049e83
2 changed files with 11 additions and 2 deletions
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3
fs/jffs2/background.c
View file

@ -132,8 +132,7 @@ static int jffs2_garbage_collect_thread(void *_c)
case SIGSTOP: case SIGSTOP:
jffs2_dbg(1, "%s(): SIGSTOP received\n", jffs2_dbg(1, "%s(): SIGSTOP received\n",
__func__); __func__);
set_current_state(TASK_STOPPED); kernel_signal_stop();
schedule();
break; break;
case SIGKILL: case SIGKILL:

10
include/linux/sched.h
View file

@ -2475,6 +2475,16 @@ static inline int kernel_dequeue_signal(siginfo_t *info)
return ret; return ret;
} }
static inline void kernel_signal_stop(void)
{
spin_lock_irq(&current->sighand->siglock);
if (current->jobctl & JOBCTL_STOP_DEQUEUED)
__set_current_state(TASK_STOPPED);
spin_unlock_irq(&current->sighand->siglock);
schedule();
}
extern void release_task(struct task_struct * p); extern void release_task(struct task_struct * p);
extern int send_sig_info(int, struct siginfo *, struct task_struct *); extern int send_sig_info(int, struct siginfo *, struct task_struct *);
extern int force_sigsegv(int, struct task_struct *); extern int force_sigsegv(int, struct task_struct *);