Messages in this thread Patch in this message | | | Date | Sat, 24 Mar 2012 15:00:24 +0400 | From | Anton Vorontsov <> | Subject | [PATCH] sysrq: Use SEND_SIG_FORCED instead of force_sig() |
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Change send_sig_all() to use do_send_sig_info(SEND_SIG_FORCED) instead of force_sig(SIGKILL). With the recent changes we do not need force_ to kill the CLONE_NEWPID tasks.
And this is more correct. force_sig() can race with the exiting thread, while do_send_sig_info(group => true) kill the whole process.
Some more notes from Oleg Nesterov:
> Just one note. This change makes no difference for sysrq_handle_kill(). > But it obviously changes the behaviour sysrq_handle_term(). I think > this is fine, if you want to really kill the task which blocks/ignores > SIGTERM you can use sysrq_handle_kill(). > > Even ignoring the reasons why force_sig() is simply wrong here, > force_sig(SIGTERM) looks strange. The task won't be killed if it has > a handler, but SIG_IGN can't help. However if it has the handler > but blocks SIGTERM temporary (this is very common) it will be killed.
Also,
> force_sig() can't kill the process if the main thread has already > exited. IOW, it is trivial to create the process which can't be > killed by sysrq.
So, this patch fixes the issue.
Suggested-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Acked-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org> ---
The patch depends on a few Oleg's patches in -mm, so I believe this should be -mm material as well.
drivers/tty/sysrq.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c index 8db9125..5ab8039 100644 --- a/drivers/tty/sysrq.c +++ b/drivers/tty/sysrq.c @@ -329,7 +329,7 @@ static void send_sig_all(int sig) if (is_global_init(p)) continue; - force_sig(sig, p); + do_send_sig_info(sig, SEND_SIG_FORCED, p, true); } read_unlock(&tasklist_lock); } -- 1.7.9.2
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