diff options
author | Roland McGrath <roland@redhat.com> | 2007-05-23 13:57:44 -0700 |
---|---|---|
committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-05-23 20:14:12 -0700 |
commit | 7bb44adef39ad3bda2be40bb34686bc56bd563a5 (patch) | |
tree | 1e9eecbd03877c7ac8b00a8cb1d4ae54ebec3bb1 /kernel | |
parent | 3c6df2a9177c010bf811c361149069e4bfd9bb11 (diff) | |
download | op-kernel-dev-7bb44adef39ad3bda2be40bb34686bc56bd563a5.zip op-kernel-dev-7bb44adef39ad3bda2be40bb34686bc56bd563a5.tar.gz |
recalc_sigpending_tsk fixes
Steve Hawkes discovered a problem where recalc_sigpending_tsk was called in
do_sigaction but no signal_wake_up call was made, preventing later signals
from waking up blocked threads with TIF_SIGPENDING already set.
In fact, the few other calls to recalc_sigpending_tsk outside the signals
code are also subject to this problem in other race conditions.
This change makes recalc_sigpending_tsk private to the signals code. It
changes the outside calls, as well as do_sigaction, to use the new
recalc_sigpending_and_wake instead.
Signed-off-by: Roland McGrath <roland@redhat.com>
Cc: <Steve.Hawkes@motorola.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
-rw-r--r-- | kernel/exit.c | 7 | ||||
-rw-r--r-- | kernel/power/process.c | 2 | ||||
-rw-r--r-- | kernel/signal.c | 24 |
3 files changed, 21 insertions, 12 deletions
diff --git a/kernel/exit.c b/kernel/exit.c index c6d14b8..5b888c2 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -762,11 +762,8 @@ static void exit_notify(struct task_struct *tsk) read_lock(&tasklist_lock); spin_lock_irq(&tsk->sighand->siglock); for (t = next_thread(tsk); t != tsk; t = next_thread(t)) - if (!signal_pending(t) && !(t->flags & PF_EXITING)) { - recalc_sigpending_tsk(t); - if (signal_pending(t)) - signal_wake_up(t, 0); - } + if (!signal_pending(t) && !(t->flags & PF_EXITING)) + recalc_sigpending_and_wake(t); spin_unlock_irq(&tsk->sighand->siglock); read_unlock(&tasklist_lock); } diff --git a/kernel/power/process.c b/kernel/power/process.c index d31d638..e0233d8 100644 --- a/kernel/power/process.c +++ b/kernel/power/process.c @@ -101,7 +101,7 @@ static void cancel_freezing(struct task_struct *p) pr_debug(" clean up: %s\n", p->comm); do_not_freeze(p); spin_lock_irqsave(&p->sighand->siglock, flags); - recalc_sigpending_tsk(p); + recalc_sigpending_and_wake(p); spin_unlock_irqrestore(&p->sighand->siglock, flags); } } diff --git a/kernel/signal.c b/kernel/signal.c index 364fc95..acdfc05 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -96,15 +96,27 @@ static inline int has_pending_signals(sigset_t *signal, sigset_t *blocked) #define PENDING(p,b) has_pending_signals(&(p)->signal, (b)) -fastcall void recalc_sigpending_tsk(struct task_struct *t) +static int recalc_sigpending_tsk(struct task_struct *t) { if (t->signal->group_stop_count > 0 || (freezing(t)) || PENDING(&t->pending, &t->blocked) || - PENDING(&t->signal->shared_pending, &t->blocked)) + PENDING(&t->signal->shared_pending, &t->blocked)) { set_tsk_thread_flag(t, TIF_SIGPENDING); - else - clear_tsk_thread_flag(t, TIF_SIGPENDING); + return 1; + } + clear_tsk_thread_flag(t, TIF_SIGPENDING); + return 0; +} + +/* + * After recalculating TIF_SIGPENDING, we need to make sure the task wakes up. + * This is superfluous when called on current, the wakeup is a harmless no-op. + */ +void recalc_sigpending_and_wake(struct task_struct *t) +{ + if (recalc_sigpending_tsk(t)) + signal_wake_up(t, 0); } void recalc_sigpending(void) @@ -744,7 +756,7 @@ force_sig_info(int sig, struct siginfo *info, struct task_struct *t) action->sa.sa_handler = SIG_DFL; if (blocked) { sigdelset(&t->blocked, sig); - recalc_sigpending_tsk(t); + recalc_sigpending_and_wake(t); } } ret = specific_send_sig_info(sig, info, t); @@ -2273,7 +2285,7 @@ int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact) rm_from_queue_full(&mask, &t->signal->shared_pending); do { rm_from_queue_full(&mask, &t->pending); - recalc_sigpending_tsk(t); + recalc_sigpending_and_wake(t); t = next_thread(t); } while (t != current); } |