[PATCH 1/3] signals: Allow generation of SIGKILL to exiting task.
oleg at redhat.com
Wed Apr 25 13:13:50 UTC 2018
On 04/24, Andrey Grodzovsky wrote:
> Currently calling wait_event_killable as part of exiting process
> will stall forever since SIGKILL generation is suppresed by PF_EXITING.
See my reply to 2/3,
> In our partilaur case AMDGPU driver wants to flush all GPU jobs in
> flight before shutting down. But if some job hangs the pipe we still want to
> be able to kill it and avoid a process in D state.
this patch won't really help in multi-threaded case,
> --- a/kernel/signal.c
> +++ b/kernel/signal.c
> @@ -886,10 +886,10 @@ static inline int wants_signal(int sig, struct task_struct *p)
> if (sigismember(&p->blocked, sig))
> return 0;
> - if (p->flags & PF_EXITING)
> - return 0;
> if (sig == SIGKILL)
> return 1;
> + if (p->flags & PF_EXITING)
> + return 0;
So you want to trigger signal_wake_up() at the end of complete_signal().
Unless you use tkill() you can wake another thread, not the thread blocked
And if the whole process is already dying complete_signal() will do nothing
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