The patch titled
signals: consolidate send_sigqueue and send_group_sigqueue
has been added to the -mm tree. Its filename is
signals-consolidate-send_sigqueue-and-send_group_sigqueue.patch
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Subject: signals: consolidate send_sigqueue and send_group_sigqueue
From: Pavel Emelyanov <xemul@xxxxxxxxxx>
Both functions do the same thing after proper locking, but with different
sigpening structs, so move the common code into a helper.
After this we have 4 places that look very similar: send_sigqueue: calls
do_send_sigqueue and signal_wakeup send_group_sigqueue: calls do_send_sigqueue
and __group_complete_signal __group_send_sig_info: calls send_signal and
__group_complete_signal specific_send_sig_info: calls send_signal and
signal_wakeup
Besides, send_signal performs actions similar to do_send_sigqueue's
and __group_complete_signal - to signal_wakeup.
It looks like they can be consolidated gracefully.
Oleg said:
Personally, I think this change is very good. But send_sigqueue() and
send_group_sigqueue() have a very subtle difference which I was never able
to understand.
Let's suppose that sigqueue is already queued, and the signal is ignored
(the latter means we should re-schedule cpu timer or handle overrruns). In
that case send_sigqueue() returns 0, but send_group_sigqueue() returns 1.
I think this is not the problem (in fact, I think this patch makes the
behaviour more correct), but I hope Thomas can take a look and confirm.
Signed-off-by: Pavel Emelyanov <xemul@xxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Roland McGrath <roland@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/signal.c | 86 +++++++++++++++-------------------------------
1 file changed, 29 insertions(+), 57 deletions(-)
diff -puN kernel/signal.c~signals-consolidate-send_sigqueue-and-send_group_sigqueue kernel/signal.c
--- a/kernel/signal.c~signals-consolidate-send_sigqueue-and-send_group_sigqueue
+++ a/kernel/signal.c
@@ -1290,10 +1290,33 @@ void sigqueue_free(struct sigqueue *q)
__sigqueue_free(q);
}
+static int do_send_sigqueue(int sig, struct sigqueue *q, struct task_struct *t,
+ struct sigpending *pending)
+{
+ if (unlikely(!list_empty(&q->list))) {
+ /*
+ * If an SI_TIMER entry is already queue just increment
+ * the overrun count.
+ */
+
+ BUG_ON(q->info.si_code != SI_TIMER);
+ q->info.si_overrun++;
+ return 0;
+ }
+
+ if (sig_ignored(t, sig))
+ return 1;
+
+ signalfd_notify(t, sig);
+ list_add_tail(&q->list, &pending->list);
+ sigaddset(&pending->signal, sig);
+ return 0;
+}
+
int send_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
{
unsigned long flags;
- int ret = 0;
+ int ret = -1;
BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
@@ -1307,37 +1330,14 @@ int send_sigqueue(int sig, struct sigque
*/
rcu_read_lock();
- if (!likely(lock_task_sighand(p, &flags))) {
- ret = -1;
+ if (!likely(lock_task_sighand(p, &flags)))
goto out_err;
- }
- if (unlikely(!list_empty(&q->list))) {
- /*
- * If an SI_TIMER entry is already queue just increment
- * the overrun count.
- */
- BUG_ON(q->info.si_code != SI_TIMER);
- q->info.si_overrun++;
- goto out;
- }
- /* Short-circuit ignored signals. */
- if (sig_ignored(p, sig)) {
- ret = 1;
- goto out;
- }
- /*
- * Deliver the signal to listening signalfds. This must be called
- * with the sighand lock held.
- */
- signalfd_notify(p, sig);
+ ret = do_send_sigqueue(sig, q, p, &p->pending);
- list_add_tail(&q->list, &p->pending.list);
- sigaddset(&p->pending.signal, sig);
if (!sigismember(&p->blocked, sig))
signal_wake_up(p, sig == SIGKILL);
-out:
unlock_task_sighand(p, &flags);
out_err:
rcu_read_unlock();
@@ -1349,7 +1349,7 @@ int
send_group_sigqueue(int sig, struct sigqueue *q, struct task_struct *p)
{
unsigned long flags;
- int ret = 0;
+ int ret;
BUG_ON(!(q->flags & SIGQUEUE_PREALLOC));
@@ -1358,38 +1358,10 @@ send_group_sigqueue(int sig, struct sigq
spin_lock_irqsave(&p->sighand->siglock, flags);
handle_stop_signal(sig, p);
- /* Short-circuit ignored signals. */
- if (sig_ignored(p, sig)) {
- ret = 1;
- goto out;
- }
-
- if (unlikely(!list_empty(&q->list))) {
- /*
- * If an SI_TIMER entry is already queue just increment
- * the overrun count. Other uses should not try to
- * send the signal multiple times.
- */
- BUG_ON(q->info.si_code != SI_TIMER);
- q->info.si_overrun++;
- goto out;
- }
- /*
- * Deliver the signal to listening signalfds. This must be called
- * with the sighand lock held.
- */
- signalfd_notify(p, sig);
-
- /*
- * Put this signal on the shared-pending queue.
- * We always use the shared queue for process-wide signals,
- * to avoid several races.
- */
- list_add_tail(&q->list, &p->signal->shared_pending.list);
- sigaddset(&p->signal->shared_pending.signal, sig);
+ ret = do_send_sigqueue(sig, q, p, &p->signal->shared_pending);
__group_complete_signal(sig, p);
-out:
+
spin_unlock_irqrestore(&p->sighand->siglock, flags);
read_unlock(&tasklist_lock);
return ret;
_
Patches currently in -mm which might be from xemul@xxxxxxxxxx are
use-find_task_by_vpid-in-audit-code.patch
ia64-fix-ptrace-inside-a-namespace.patch
udf-fix-anchor-point-detection.patch
remove-unused-variable-from-send_signal.patch
turn-legacy_queue-macro-into-static-inline-function.patch
consolidate-checking-for-ignored-legacy-signals.patch
consolidate-checking-for-ignored-legacy-signals-simplify.patch
signals-consolidate-checks-for-whether-or-not-to-ignore-a-signal.patch
signals-clean-dequeue_signal-from-excess-checks-and-assignments.patch
signals-consolidate-send_sigqueue-and-send_group_sigqueue.patch
free_pidmap-turn-it-into-free_pidmapstruct-upid.patch
use-find_task_by_vpid-in-taskstats.patch
deprecate-find_task_by_pid.patch
reiser4.patch
put_pid-make-sure-we-dont-free-the-live-pid.patch
-
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