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Fix force_sig_info() semantics after cleanups

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Suresh points out that commit b0423a0d9cc836b2c3d796623cd19236bfedfe63
broke the semantics of a synchronous signal like SIGSEGV occurring
recursively inside its own handler handler (or, indeed, any other
context when the signal was blocked).

That was unintentional, and this fixes things up by reinstating the old
semantics, but without reverting the cleanups.

Cc: Paul E. McKenney <paulmck@us.ibm.com>
Acked-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Linus Torvalds 2006-08-02 20:17:49 -07:00
parent 202668ecb6
commit ae74c3b69a
1 changed files with 17 additions and 8 deletions
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25
kernel/signal.c
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@ -791,22 +791,31 @@ out:
/* /*
* Force a signal that the process can't ignore: if necessary * Force a signal that the process can't ignore: if necessary
* we unblock the signal and change any SIG_IGN to SIG_DFL. * we unblock the signal and change any SIG_IGN to SIG_DFL.
*
* Note: If we unblock the signal, we always reset it to SIG_DFL,
* since we do not want to have a signal handler that was blocked
* be invoked when user space had explicitly blocked it.
*
* We don't want to have recursive SIGSEGV's etc, for example.
*/ */
int int
force_sig_info(int sig, struct siginfo *info, struct task_struct *t) force_sig_info(int sig, struct siginfo *info, struct task_struct *t)
{ {
unsigned long int flags; unsigned long int flags;
int ret; int ret, blocked, ignored;
struct k_sigaction *action;
spin_lock_irqsave(&t->sighand->siglock, flags); spin_lock_irqsave(&t->sighand->siglock, flags);
if (t->sighand->action[sig-1].sa.sa_handler == SIG_IGN) { action = &t->sighand->action[sig-1];
t->sighand->action[sig-1].sa.sa_handler = SIG_DFL; ignored = action->sa.sa_handler == SIG_IGN;
blocked = sigismember(&t->blocked, sig);
if (blocked || ignored) {
action->sa.sa_handler = SIG_DFL;
if (blocked) {
sigdelset(&t->blocked, sig);
recalc_sigpending_tsk(t);
}
} }
if (sigismember(&t->blocked, sig)) {
sigdelset(&t->blocked, sig);
}
recalc_sigpending_tsk(t);
ret = specific_send_sig_info(sig, info, t); ret = specific_send_sig_info(sig, info, t);
spin_unlock_irqrestore(&t->sighand->siglock, flags); spin_unlock_irqrestore(&t->sighand->siglock, flags);