diff mbox series

[v2,03/44] cpuidle/poll: Ensure IRQ state is invariant

Message ID 20220919101520.534233547@infradead.org
State Superseded
Headers show
Series cpuidle,rcu: Clean up the mess | expand

Commit Message

Peter Zijlstra Sept. 19, 2022, 9:59 a.m. UTC 
cpuidle_state::enter() methods should be IRQ invariant

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 drivers/cpuidle/poll_state.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

Comments

Frederic Weisbecker Sept. 19, 2022, 1:19 p.m. UTC | #1 
On Mon, Sep 19, 2022 at 11:59:42AM +0200, Peter Zijlstra wrote:
> cpuidle_state::enter() methods should be IRQ invariant

Got a bit confused with the invariant thing since the first chunck I
see in this patch is a conversion to an non-traceable local_irq_enable().

Maybe just add a short mention about that and why?

Thanks.

> 
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> ---
>  drivers/cpuidle/poll_state.c |    4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> --- a/drivers/cpuidle/poll_state.c
> +++ b/drivers/cpuidle/poll_state.c
> @@ -17,7 +17,7 @@ static int __cpuidle poll_idle(struct cp
>  
>  	dev->poll_time_limit = false;
>  
> -	local_irq_enable();
> +	raw_local_irq_enable();
>  	if (!current_set_polling_and_test()) {
>  		unsigned int loop_count = 0;
>  		u64 limit;
> @@ -36,6 +36,8 @@ static int __cpuidle poll_idle(struct cp
>  			}
>  		}
>  	}
> +	raw_local_irq_disable();
> +
>  	current_clr_polling();
>  
>  	return index;
> 
>
Peter Zijlstra Sept. 20, 2022, 8:57 a.m. UTC | #2 
On Mon, Sep 19, 2022 at 03:19:27PM +0200, Frederic Weisbecker wrote:
> On Mon, Sep 19, 2022 at 11:59:42AM +0200, Peter Zijlstra wrote:
> > cpuidle_state::enter() methods should be IRQ invariant
> 
> Got a bit confused with the invariant thing since the first chunck I
> see in this patch is a conversion to an non-traceable local_irq_enable().
> 
> Maybe just add a short mention about that and why?

Changelog now reads:

---
Subject: cpuidle/poll: Ensure IRQ state is invariant
From: Peter Zijlstra <peterz@infradead.org>
Date: Tue May 31 15:43:32 CEST 2022

cpuidle_state::enter() methods should be IRQ invariant.

Additionally make sure to use raw_local_irq_*() methods since this
cpuidle callback will be called with RCU already disabled.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
diff mbox series

Patch

--- a/drivers/cpuidle/poll_state.c
+++ b/drivers/cpuidle/poll_state.c
@@ -17,7 +17,7 @@  static int __cpuidle poll_idle(struct cp
 
 	dev->poll_time_limit = false;
 
-	local_irq_enable();
+	raw_local_irq_enable();
 	if (!current_set_polling_and_test()) {
 		unsigned int loop_count = 0;
 		u64 limit;
@@ -36,6 +36,8 @@  static int __cpuidle poll_idle(struct cp
 			}
 		}
 	}
+	raw_local_irq_disable();
+
 	current_clr_polling();
 
 	return index;