diff options
author | Oleg Nesterov <oleg@redhat.com> | 2011-04-27 14:59:41 -0400 |
---|---|---|
committer | Oleg Nesterov <oleg@redhat.com> | 2011-04-28 07:01:37 -0400 |
commit | e6fa16ab9c1e9b344428e6fea4d29e3cc4b28fb0 (patch) | |
tree | c1bdacc0537213cba8ba75a63ac286e21c0a7250 /include/linux/signal.h | |
parent | 73ef4aeb61b53fce464a7e24ef03a26f98b2f617 (diff) |
signal: sigprocmask() should do retarget_shared_pending()
In short, almost every changing of current->blocked is wrong, or at least
can lead to the unexpected results.
For example. Two threads T1 and T2, T1 sleeps in sigtimedwait/pause/etc.
kill(tgid, SIG) can pick T2 for TIF_SIGPENDING. If T2 calls sigprocmask()
and blocks SIG before it notices the pending signal, nobody else can handle
this pending shared signal.
I am not sure this is bug, but at least this looks strange imho. T1 should
not sleep forever, there is a signal which should wake it up.
This patch moves the code which actually changes ->blocked into the new
helper, set_current_blocked() and changes this code to call
retarget_shared_pending() as exit_signals() does. We should only care about
the signals we just blocked, we use "newset & ~current->blocked" as a mask.
We do not check !sigisemptyset(newblocked), retarget_shared_pending() is
cheap unless mask & shared_pending.
Note: for this particular case we could simply change sigprocmask() to
return -EINTR if signal_pending(), but then we should change other callers
and, more importantly, if we need this fix then set_current_blocked() will
have more callers and some of them can't restart. See the next patch as a
random example.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Matt Fleming <matt.fleming@linux.intel.com>
Acked-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'include/linux/signal.h')
-rw-r--r-- | include/linux/signal.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/signal.h b/include/linux/signal.h index fcd2b14b1932..ba009c167275 100644 --- a/include/linux/signal.h +++ b/include/linux/signal.h | |||
@@ -243,6 +243,7 @@ extern long do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, | |||
243 | siginfo_t *info); | 243 | siginfo_t *info); |
244 | extern long do_sigpending(void __user *, unsigned long); | 244 | extern long do_sigpending(void __user *, unsigned long); |
245 | extern int sigprocmask(int, sigset_t *, sigset_t *); | 245 | extern int sigprocmask(int, sigset_t *, sigset_t *); |
246 | extern void set_current_blocked(const sigset_t *); | ||
246 | extern int show_unhandled_signals; | 247 | extern int show_unhandled_signals; |
247 | 248 | ||
248 | struct pt_regs; | 249 | struct pt_regs; |