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Subject[PATCH v1] signal.c: repeatedly set the TIF_SIGPENDING flag
Date
The recalc_sigpending_and_wake() function calls recalc_sigpending_tsk() and signal_wake_up(),
both of which set the TIF_SIGPENDING flag, so when recalc_sigpending_tsk() returns true,
the TIF_SIGPENDING flag will be set twice.

Maybe we can take away the set TIF_SIGPENDING logic from recalc_sigpending_tsk(),
so that recalc_sigpending_tsk() just determines whether the TIF_SIGPENDING flag needs to be set,
and the actual set TIF_SIGPENDING flag logic is executed outside.

kernel/signal.c:175: recalc_sigpending_and_wake()
kernel/signal.c:154: recalc_sigpending_tsk()

Signed-off-by: Hao Wu <guoyuanchao1202@gmail.com>
---
kernel/signal.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/kernel/signal.c b/kernel/signal.c
index 9b04631acde8..6c5a00cd7e9a 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -157,7 +157,6 @@ static bool recalc_sigpending_tsk(struct task_struct *t)
PENDING(&t->pending, &t->blocked) ||
PENDING(&t->signal->shared_pending, &t->blocked) ||
cgroup_task_frozen(t)) {
- set_tsk_thread_flag(t, TIF_SIGPENDING);
return true;
}
@@ -181,8 +180,11 @@ void recalc_sigpending_and_wake(struct task_struct *t)
void recalc_sigpending(void)
{
- if (!recalc_sigpending_tsk(current) && !freezing(current))
+ if (recalc_sigpending_tsk(current)) {
+ set_tsk_thread_flag(t, TIF_SIGPENDING);
+ } else if (!freezing(current)) {
clear_thread_flag(TIF_SIGPENDING);
+ }
}
EXPORT_SYMBOL(recalc_sigpending);
@@ -2325,7 +2327,9 @@ static void ptrace_stop(int exit_code, int why, int clear_code, kernel_siginfo_t
* So check for any that we should take before resuming user mode.
* This sets TIF_SIGPENDING, but never clears it.
*/
- recalc_sigpending_tsk(current);
+ if (recalc_sigpending_tsk(current)) {
+ set_tsk_thread_flag(t, TIF_SIGPENDING);
+ }
}
static void ptrace_do_notify(int signr, int exit_code, int why)
2.32.0
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