The patch titled
signals: introduce SIGQUEUE_CANCELLED
has been added to the -mm tree. Its filename is
signals-introduce-sigqueue_cancelled.patch
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------------------------------------------------------
Subject: signals: introduce SIGQUEUE_CANCELLED
From: Oleg Nesterov <oleg@xxxxxxxxxx>
Suggested by Linus Torvalds.
Introduce SIGQUEUE_CANCELLED flag. If it is set, the pending signal
should be ignored and collect_signal() should return 0.
Note that the new flag is completely orthogonal to SIGQUEUE_PREALLOC, and it
can be set without ->siglock held.
No users of this new flag yet, see the next patch.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Roland McGrath <roland@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/signal.h | 1 +
kernel/signal.c | 13 +++++++------
2 files changed, 8 insertions(+), 6 deletions(-)
diff -puN include/linux/signal.h~signals-introduce-sigqueue_cancelled include/linux/signal.h
--- a/include/linux/signal.h~signals-introduce-sigqueue_cancelled
+++ a/include/linux/signal.h
@@ -20,6 +20,7 @@ struct sigqueue {
/* flags values. */
#define SIGQUEUE_PREALLOC 1
+#define SIGQUEUE_CANCELLED 2
struct sigpending {
struct list_head list;
diff -puN kernel/signal.c~signals-introduce-sigqueue_cancelled kernel/signal.c
--- a/kernel/signal.c~signals-introduce-sigqueue_cancelled
+++ a/kernel/signal.c
@@ -326,11 +326,13 @@ static int collect_signal(int sig, struc
}
}
if (first) {
- list_del_init(&first->list);
- copy_siginfo(info, &first->info);
- __sigqueue_free(first);
if (!still_pending)
sigdelset(&list->signal, sig);
+ if (unlikely(first->flags & SIGQUEUE_CANCELLED))
+ sig = 0;
+ copy_siginfo(info, &first->info);
+ list_del_init(&first->list);
+ __sigqueue_free(first);
} else {
/* Ok, it wasn't in the queue. This must be
@@ -344,7 +346,7 @@ static int collect_signal(int sig, struc
info->si_pid = 0;
info->si_uid = 0;
}
- return 1;
+ return sig;
}
static int __dequeue_signal(struct sigpending *pending, sigset_t *mask,
@@ -362,8 +364,7 @@ static int __dequeue_signal(struct sigpe
}
}
- if (!collect_signal(sig, pending, info))
- sig = 0;
+ sig = collect_signal(sig, pending, info);
}
return sig;
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
signals-fix-sigqueue_free-vs-__exit_signal-race.patch
posix-timers-timer_delete-remove-the-bogus-it_process-=-null-check.patch
posix-timers-release_posix_timer-kill-the-bogus-put_task_struct-it_process.patch
signals-sigqueue_free-dont-free-sigqueue-if-it-is-queued.patch
signals-introduce-sigqueue_cancelled.patch
posix-timers-use-sigqueue_cancelled-when-the-timer-is-destroyed.patch
put_pid-make-sure-we-dont-free-the-live-pid.patch
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