linux-kernel - [tip: timers/core] posix-cpu-timers: Use dedicated flag for CPU timer nanosleep

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Message-ID: <173094310087.32228.4688172468522182830.tip-bot2@tip-bot2>
Date: Thu, 07 Nov 2024 01:31:40 -0000
From: "tip-bot2 for Thomas Gleixner" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Thomas Gleixner <tglx@...utronix.de>,
 Frederic Weisbecker <frederic@...nel.org>,
 "Peter Zijlstra (Intel)" <peterz@...radead.org>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject: [tip: timers/core] posix-cpu-timers: Use dedicated flag for CPU timer
 nanosleep

The following commit has been merged into the timers/core branch of tip:

Commit-ID:     4cf7bf2a2f1a8ace4a49a1138c8123fdb5990093
Gitweb:        https://git.kernel.org/tip/4cf7bf2a2f1a8ace4a49a1138c8123fdb5990093
Author:        Thomas Gleixner <tglx@...utronix.de>
AuthorDate:    Tue, 05 Nov 2024 09:14:35 +01:00
Committer:     Thomas Gleixner <tglx@...utronix.de>
CommitterDate: Thu, 07 Nov 2024 02:14:43 +01:00

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@...utronix.de>
Reviewed-by: Frederic Weisbecker <frederic@...nel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Link: https://lore.kernel.org/all/20241105064213.238550394@linutronix.de


---
 include/linux/posix-timers.h   | 2 ++
 kernel/time/posix-cpu-timers.c | 3 ++-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/include/linux/posix-timers.h b/include/linux/posix-timers.h
index b1de217..bcd0120 100644
--- a/include/linux/posix-timers.h
+++ b/include/linux/posix-timers.h
@@ -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;
 };
 
diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c
index a282a3c..0c441d8 100644
--- a/kernel/time/posix-cpu-timers.c
+++ b/kernel/time/posix-cpu-timers.c
@@ -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;