signals: handle_stop_signal: don't worry about SIGKILL
authorOleg Nesterov <oleg@tv-sign.ru>
Wed, 30 Apr 2008 07:52:58 +0000 (00:52 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Wed, 30 Apr 2008 15:29:36 +0000 (08:29 -0700)
commit34c8f07b9ac499a807918eda377193a55f64f8df
tree042cf061406273dcfdb3fabe4b07425e4cb8f0aa
parentac5c215383f43a106ba4ef298126bf78c126f5e9
signals: handle_stop_signal: don't worry about SIGKILL

handle_stop_signal() clears SIGNAL_STOP_DEQUEUED when sig == SIGKILL.  Remove
this nasty special case.  It was needed to prevent the race with group stop
and exit caused by thread-specific SIGKILL.  Now that we use complete_signal()
for private signals too this is not needed, complete_signal() will notice
SIGKILL and abort the soon-to-begin group stop.

Except: the target thread is dead (has PF_EXITING).  But in that case we
should not just clear SIGNAL_STOP_DEQUEUED and nothing more.  We should either
kill the whole thread group, or silently ignore the signal.

I suspect we are not right wrt zombie leaders, but this is another issue which
and should be fixed separately.  Note that this check can't abort the group
stop if it was already started/finished, this check only adds a subtle side
effect if we race with the thread which has already dequeued sig_kernel_stop()
signal and temporary released ->siglock.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
kernel/signal.c