From 9a13049e83f346cb1cbd60c64e520a73c396af16 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Fri, 6 Nov 2015 16:32:25 -0800 Subject: signal: introduce kernel_signal_stop() to fix jffs2_garbage_collect_thread() 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 Reviewed-by: Tejun Heo Cc: David Woodhouse Cc: Felipe Balbi Cc: Markus Pargmann Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/jffs2/background.c | 3 +-- include/linux/sched.h | 10 ++++++++++ 2 files changed, 11 insertions(+), 2 deletions(-) diff --git a/fs/jffs2/background.c b/fs/jffs2/background.c index f3145fd..53cc735 100644 --- a/fs/jffs2/background.c +++ b/fs/jffs2/background.c @@ -132,8 +132,7 @@ static int jffs2_garbage_collect_thread(void *_c) case SIGSTOP: jffs2_dbg(1, "%s(): SIGSTOP received\n", __func__); - set_current_state(TASK_STOPPED); - schedule(); + kernel_signal_stop(); break; case SIGKILL: diff --git a/include/linux/sched.h b/include/linux/sched.h index 3d54924..4069feb 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -2475,6 +2475,16 @@ static inline int kernel_dequeue_signal(siginfo_t *info) return ret; } +static inline void kernel_signal_stop(void) +{ + spin_lock_irq(¤t->sighand->siglock); + if (current->jobctl & JOBCTL_STOP_DEQUEUED) + __set_current_state(TASK_STOPPED); + spin_unlock_irq(¤t->sighand->siglock); + + schedule(); +} + extern void release_task(struct task_struct * p); extern int send_sig_info(int, struct siginfo *, struct task_struct *); extern int force_sigsegv(int, struct task_struct *); -- cgit v1.1