The patch titled Subject: kernel/signal.c: simplify force_sig_info_to_task(), kill recalc_sigpending_and_wake() has been added to the -mm mm-nonmm-unstable branch. Its filename is simplify-force_sig_info_to_task-kill-recalc_sigpending_and_wake.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/simplify-force_sig_info_to_task-kill-recalc_sigpending_and_wake.patch This patch will later appear in the mm-nonmm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Oleg Nesterov <oleg@xxxxxxxxxx> Subject: kernel/signal.c: simplify force_sig_info_to_task(), kill recalc_sigpending_and_wake() Date: Mon, 20 Nov 2023 16:16:49 +0100 The purpose of recalc_sigpending_and_wake() is not clear, it looks "obviously unneeded" because we are going to send the signal which can't be blocked or ignored. Add the comment to explain why we can't rely on send_signal_locked() and make this logic more simple/explicit. recalc_sigpending_and_wake() has no other users, it can die. In fact I think we don't even need signal_wake_up(), the target task must be either current or a TASK_TRACED child, otherwise the usage of siglock is not safe. But this needs another change. Link: https://lkml.kernel.org/r/20231120151649.GA15995@xxxxxxxxxx Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx> Cc: Eric Biederman <ebiederm@xxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/sched/signal.h | 1 - kernel/signal.c | 17 ++++------------- 2 files changed, 4 insertions(+), 14 deletions(-) --- a/include/linux/sched/signal.h~simplify-force_sig_info_to_task-kill-recalc_sigpending_and_wake +++ a/include/linux/sched/signal.h @@ -432,7 +432,6 @@ static inline bool fault_signal_pending( * This is required every time the blocked sigset_t changes. * callers must hold sighand->siglock. */ -extern void recalc_sigpending_and_wake(struct task_struct *t); extern void recalc_sigpending(void); extern void calculate_sigpending(void); --- a/kernel/signal.c~simplify-force_sig_info_to_task-kill-recalc_sigpending_and_wake +++ a/kernel/signal.c @@ -171,16 +171,6 @@ static bool recalc_sigpending_tsk(struct return false; } -/* - * 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) { if (!recalc_sigpending_tsk(current) && !freezing(current)) @@ -1348,10 +1338,8 @@ force_sig_info_to_task(struct kernel_sig action->sa.sa_handler = SIG_DFL; if (handler == HANDLER_EXIT) action->sa.sa_flags |= SA_IMMUTABLE; - if (blocked) { + if (blocked) sigdelset(&t->blocked, sig); - recalc_sigpending_and_wake(t); - } } /* * Don't clear SIGNAL_UNKILLABLE for traced tasks, users won't expect @@ -1361,6 +1349,9 @@ force_sig_info_to_task(struct kernel_sig (!t->ptrace || (handler == HANDLER_EXIT))) t->signal->flags &= ~SIGNAL_UNKILLABLE; ret = send_signal_locked(sig, info, t, PIDTYPE_PID); + /* This can happen if the signal was already pending and blocked */ + if (!task_sigpending(t)) + signal_wake_up(t, 0); spin_unlock_irqrestore(&t->sighand->siglock, flags); return ret; _ Patches currently in -mm which might be from oleg@xxxxxxxxxx are introduce-for_other_threadsp-t.patch simplify-force_sig_info_to_task-kill-recalc_sigpending_and_wake.patch