tree 91759a5584b9d42302d4b54ecdde644bc47e781d
parent a1d5e21e3e388fb2c16463d007e788b1e41b74f1
author Oleg Nesterov <oleg@tv-sign.ru> 1143591090 -0800
committer Linus Torvalds <torvalds@g5.osdl.org> 1143599804 -0800

[PATCH] send_sigqueue: simplify and fix the race

send_sigqueue() checks PF_EXITING, then locks p->sighand->siglock.  This is
unsafe: 'p' can exit in between and set ->sighand = NULL.  The race is
theoretical, the window is tiny and irqs are disabled by the caller, so I
don't think we need the fix for -stable tree.

Convert send_sigqueue() to use lock_task_sighand() helper.

Also, delete 'p->flags & PF_EXITING' re-check, it is unneeded and the
comment is wrong.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>