[PATCH 25/36] time/tick-broadcast: Remove RCU_NONIDLE usage

Peter Zijlstra posted 36 patches 2 years, 5 months ago
There is a newer version of this series
[PATCH 25/36] time/tick-broadcast: Remove RCU_NONIDLE usage
Posted by Peter Zijlstra 2 years, 5 months ago
No callers left that have already disabled RCU.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 kernel/time/tick-broadcast-hrtimer.c |   29 ++++++++++++-----------------
 1 file changed, 12 insertions(+), 17 deletions(-)

--- a/kernel/time/tick-broadcast-hrtimer.c
+++ b/kernel/time/tick-broadcast-hrtimer.c
@@ -56,25 +56,20 @@ static int bc_set_next(ktime_t expires,
 	 * hrtimer callback function is currently running, then
 	 * hrtimer_start() cannot move it and the timer stays on the CPU on
 	 * which it is assigned at the moment.
+	 */
+	hrtimer_start(&bctimer, expires, HRTIMER_MODE_ABS_PINNED_HARD);
+	/*
+	 * The core tick broadcast mode expects bc->bound_on to be set
+	 * correctly to prevent a CPU which has the broadcast hrtimer
+	 * armed from going deep idle.
 	 *
-	 * As this can be called from idle code, the hrtimer_start()
-	 * invocation has to be wrapped with RCU_NONIDLE() as
-	 * hrtimer_start() can call into tracing.
+	 * As tick_broadcast_lock is held, nothing can change the cpu
+	 * base which was just established in hrtimer_start() above. So
+	 * the below access is safe even without holding the hrtimer
+	 * base lock.
 	 */
-	RCU_NONIDLE( {
-		hrtimer_start(&bctimer, expires, HRTIMER_MODE_ABS_PINNED_HARD);
-		/*
-		 * The core tick broadcast mode expects bc->bound_on to be set
-		 * correctly to prevent a CPU which has the broadcast hrtimer
-		 * armed from going deep idle.
-		 *
-		 * As tick_broadcast_lock is held, nothing can change the cpu
-		 * base which was just established in hrtimer_start() above. So
-		 * the below access is safe even without holding the hrtimer
-		 * base lock.
-		 */
-		bc->bound_on = bctimer.base->cpu_base->cpu;
-	} );
+	bc->bound_on = bctimer.base->cpu_base->cpu;
+
 	return 0;
 }
Re: [PATCH 25/36] time/tick-broadcast: Remove RCU_NONIDLE usage
Posted by Mark Rutland 2 years, 5 months ago
On Wed, Jun 08, 2022 at 04:27:48PM +0200, Peter Zijlstra wrote:
> No callers left that have already disabled RCU.
> 
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>

Acked-by: Mark Rutland <mark.rutland@arm.com>

Mark.

> ---
>  kernel/time/tick-broadcast-hrtimer.c |   29 ++++++++++++-----------------
>  1 file changed, 12 insertions(+), 17 deletions(-)
> 
> --- a/kernel/time/tick-broadcast-hrtimer.c
> +++ b/kernel/time/tick-broadcast-hrtimer.c
> @@ -56,25 +56,20 @@ static int bc_set_next(ktime_t expires,
>  	 * hrtimer callback function is currently running, then
>  	 * hrtimer_start() cannot move it and the timer stays on the CPU on
>  	 * which it is assigned at the moment.
> +	 */
> +	hrtimer_start(&bctimer, expires, HRTIMER_MODE_ABS_PINNED_HARD);
> +	/*
> +	 * The core tick broadcast mode expects bc->bound_on to be set
> +	 * correctly to prevent a CPU which has the broadcast hrtimer
> +	 * armed from going deep idle.
>  	 *
> -	 * As this can be called from idle code, the hrtimer_start()
> -	 * invocation has to be wrapped with RCU_NONIDLE() as
> -	 * hrtimer_start() can call into tracing.
> +	 * As tick_broadcast_lock is held, nothing can change the cpu
> +	 * base which was just established in hrtimer_start() above. So
> +	 * the below access is safe even without holding the hrtimer
> +	 * base lock.
>  	 */
> -	RCU_NONIDLE( {
> -		hrtimer_start(&bctimer, expires, HRTIMER_MODE_ABS_PINNED_HARD);
> -		/*
> -		 * The core tick broadcast mode expects bc->bound_on to be set
> -		 * correctly to prevent a CPU which has the broadcast hrtimer
> -		 * armed from going deep idle.
> -		 *
> -		 * As tick_broadcast_lock is held, nothing can change the cpu
> -		 * base which was just established in hrtimer_start() above. So
> -		 * the below access is safe even without holding the hrtimer
> -		 * base lock.
> -		 */
> -		bc->bound_on = bctimer.base->cpu_base->cpu;
> -	} );
> +	bc->bound_on = bctimer.base->cpu_base->cpu;
> +
>  	return 0;
>  }
>  
> 
>