Commit 4cf7bf2a authored Nov 05, 2024 by Thomas Gleixner

posix-cpu-timers: Use dedicated flag for CPU timer nanosleep



POSIX CPU timer nanosleep creates a k_itimer on stack and uses the sigq
pointer to detect the nanosleep case in the expiry function.

Prepare for embedding sigqueue into struct k_itimer by using a dedicated
flag for nanosleep.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/all/20241105064213.238550394@linutronix.de

parent bf635681

include/linux/posix-timers.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -42,6 +42,7 @@ static inline int clockid_to_fd(const clockid_t clk)
		* @pid: Pointer to target task PID
		* @elist: List head for the expiry list
		* @firing: Timer is currently firing
		* @nanosleep: Timer is used for nanosleep and is not a regular posix-timer
		* @handling: Pointer to the task which handles expiry
		*/
		struct cpu_timer {
		@@ -50,6 +51,7 @@ struct cpu_timer {
		struct pid *pid;
		struct list_head elist;
		bool firing;
		bool nanosleep;
		struct task_struct __rcu *handling;
		};

kernel/time/posix-cpu-timers.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -596,7 +596,7 @@ static void cpu_timer_fire(struct k_itimer *timer)

		timer->it_status = POSIX_TIMER_DISARMED;

		if (unlikely(timer->sigq == NULL)) {
		if (unlikely(ctmr->nanosleep)) {
		/*
		* This a special case for clock_nanosleep,
		* not a normal timer from sys_timer_create.
		@@ -1493,6 +1493,7 @@ static int do_cpu_nanosleep(const clockid_t which_clock, int flags,
		timer.it_overrun = -1;
		error = posix_cpu_timer_create(&timer);
		timer.it_process = current;
		timer.it.cpu.nanosleep = true;

		if (!error) {
		static struct itimerspec64 zero_it;