signal: Add task_sigpending() helper

This is in preparation for maintaining signal_pending() as the decider of
whether or not a schedule() loop should be broken, or continue sleeping.
This is different than the core signal use cases, which really need to know
whether an actual signal is pending or not. task_sigpending() returns
non-zero if TIF_SIGPENDING is set.

Only core kernel use cases should care about the distinction between
the two, make sure those use the task_sigpending() helper.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Link: https://lore.kernel.org/r/20201026203230.386348-2-axboe@kernel.dk

diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
index 1bad18a..404145d 100644 (file)
--- a/include/linux/sched/signal.h
+++ b/include/linux/sched/signal.h
@@ -353,11 +353,16 @@ static inline int restart_syscall(void)
        return -ERESTARTNOINTR;
 }
 
-static inline int signal_pending(struct task_struct *p)
+static inline int task_sigpending(struct task_struct *p)
 {
        return unlikely(test_tsk_thread_flag(p,TIF_SIGPENDING));
 }
 
+static inline int signal_pending(struct task_struct *p)
+{
+       return task_sigpending(p);
+}
+
 static inline int __fatal_signal_pending(struct task_struct *p)
 {
        return unlikely(sigismember(&p->pending.signal, SIGKILL));
@@ -365,7 +370,7 @@ static inline int __fatal_signal_pending(struct task_struct *p)
 
 static inline int fatal_signal_pending(struct task_struct *p)
 {
-       return signal_pending(p) && __fatal_signal_pending(p);
+       return task_sigpending(p) && __fatal_signal_pending(p);
 }
 
 static inline int signal_pending_state(long state, struct task_struct *p)

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 649fd53..edd0c98 100644 (file)
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -1973,7 +1973,7 @@ bool uprobe_deny_signal(void)
 
        WARN_ON_ONCE(utask->state != UTASK_SSTEP);
 
-       if (signal_pending(t)) {
+       if (task_sigpending(t)) {
                spin_lock_irq(&t->sighand->siglock);
                clear_tsk_thread_flag(t, TIF_SIGPENDING);
                spin_unlock_irq(&t->sighand->siglock);

diff --git a/kernel/signal.c b/kernel/signal.c
index 42b67d2..b179ecc 100644 (file)
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -983,7 +983,7 @@ static inline bool wants_signal(int sig, struct task_struct *p)
        if (task_is_stopped_or_traced(p))
                return false;
 
-       return task_curr(p) || !signal_pending(p);
+       return task_curr(p) || !task_sigpending(p);
 }
 
 static void complete_signal(int sig, struct task_struct *p, enum pid_type type)
@@ -2822,7 +2822,7 @@ static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
                /* Remove the signals this thread can handle. */
                sigandsets(&retarget, &retarget, &t->blocked);
 
-               if (!signal_pending(t))
+               if (!task_sigpending(t))
                        signal_wake_up(t, 0);
 
                if (sigisemptyset(&retarget))
@@ -2856,7 +2856,7 @@ void exit_signals(struct task_struct *tsk)
 
        cgroup_threadgroup_change_end(tsk);
 
-       if (!signal_pending(tsk))
+       if (!task_sigpending(tsk))
                goto out;
 
        unblocked = tsk->blocked;
@@ -2900,7 +2900,7 @@ long do_no_restart_syscall(struct restart_block *param)
 
 static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
 {
-       if (signal_pending(tsk) && !thread_group_empty(tsk)) {
+       if (task_sigpending(tsk) && !thread_group_empty(tsk)) {
                sigset_t newblocked;
                /* A set of now blocked but previously unblocked signals. */
                sigandnsets(&newblocked, newset, &current->blocked);