2016-04-16 17:55:52

by Davidlohr Bueso

Subject: [PATCH] irq_poll: Remove redundant barrier when using clear_bit_unlock()

... as the call obviously already implies unlock/RC semantics,
therefore lets get rid of the superfluous smp_mb calls.

Signed-off-by: Davidlohr Bueso <[email protected]>
---
lib/irq_poll.c | 2 --
1 file changed, 2 deletions(-)

diff --git a/lib/irq_poll.c b/lib/irq_poll.c
index 836f7db4e548..2a6ae2720ccb 100644
--- a/lib/irq_poll.c
+++ b/lib/irq_poll.c
@@ -50,7 +50,6 @@ EXPORT_SYMBOL(irq_poll_sched);
static void __irq_poll_complete(struct irq_poll *iop)
{
list_del(&iop->list);
- smp_mb__before_atomic();
clear_bit_unlock(IRQ_POLL_F_SCHED, &iop->state);
}

@@ -161,7 +160,6 @@ EXPORT_SYMBOL(irq_poll_disable);
void irq_poll_enable(struct irq_poll *iop)
{
BUG_ON(!test_bit(IRQ_POLL_F_SCHED, &iop->state));
- smp_mb__before_atomic();
clear_bit_unlock(IRQ_POLL_F_SCHED, &iop->state);
}
EXPORT_SYMBOL(irq_poll_enable);
--
2.8.1

2016-04-19 12:24:58

by Bart Van Assche

Subject: Re: [PATCH] irq_poll: Remove redundant barrier when using clear_bit_unlock()

On 04/16/2016 01:55 PM, Davidlohr Bueso wrote:
> ... as the call obviously already implies unlock/RC semantics,
> therefore lets get rid of the superfluous smp_mb calls.

Hello Davidlohr,

Are you sure that this patch has been sent to the right person? I have
helped to review a change in this code but I'm not the maintainer of
this code.

Thanks,

Bart.

2016-04-20 04:23:49

by Davidlohr Bueso

Subject: Re: [PATCH] irq_poll: Remove redundant barrier when using clear_bit_unlock()

On Tue, 19 Apr 2016, Bart Van Assche wrote:

>On 04/16/2016 01:55 PM, Davidlohr Bueso wrote:
>>... as the call obviously already implies unlock/RC semantics,
>>therefore lets get rid of the superfluous smp_mb calls.
>
>Hello Davidlohr,
>
>Are you sure that this patch has been sent to the right person? I have
>helped to review a change in this code but I'm not the maintainer of
>this code.

Ah, adding Andrew and Ingo, not sure who is responsible for these bits.

Thanks,
Davidlohr

2016-04-25 22:22:57

by Bart Van Assche

Subject: Re: [PATCH] irq_poll: Remove redundant barrier when using clear_bit_unlock()

On 04/19/2016 09:23 PM, Davidlohr Bueso wrote:
> On Tue, 19 Apr 2016, Bart Van Assche wrote:
>
>> On 04/16/2016 01:55 PM, Davidlohr Bueso wrote:
>>> ... as the call obviously already implies unlock/RC semantics,
>>> therefore lets get rid of the superfluous smp_mb calls.
>>
>> Hello Davidlohr,
>>
>> Are you sure that this patch has been sent to the right person? I have
>> helped to review a change in this code but I'm not the maintainer of
>> this code.
>
> Ah, adding Andrew and Ingo, not sure who is responsible for these bits.

Please also CC Jens Axboe and Christoph Hellwig. Jens is the original
author of this code. See also "block: add blk-iopoll, a NAPI like
approach for block devices"
(https://groups.google.com/forum/#!topic/linux.kernel/aMhcMrYaXC8).

Bart.