2020-02-26 04:25:43

by luanshi

Subject: [PATCH] perf: arm_spe: remove unnecessary zero check

The "nr_pages" variable has been checked before, it can't be zero, so a check here would be useless.

Signed-off-by: Liguang Zhang <[email protected]>
---
drivers/perf/arm_spe_pmu.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/perf/arm_spe_pmu.c b/drivers/perf/arm_spe_pmu.c
index 4e4984a..b72c048 100644
--- a/drivers/perf/arm_spe_pmu.c
+++ b/drivers/perf/arm_spe_pmu.c
@@ -831,7 +831,7 @@ static void *arm_spe_pmu_setup_aux(struct perf_event *event, void **pages,
* parts and give userspace a fighting chance of getting some
* useful data out of it.
*/
- if (!nr_pages || (snapshot && (nr_pages & 1)))
+ if (snapshot && (nr_pages & 1))
return NULL;

if (cpu == -1)
--
1.8.3.1

2020-03-09 10:54:04

by Mark Rutland

Subject: Re: [PATCH] perf: arm_spe: remove unnecessary zero check

On Wed, Feb 26, 2020 at 12:25:06PM +0800, luanshi wrote:
> The "nr_pages" variable has been checked before, it can't be zero, so a check here would be useless.
>
> Signed-off-by: Liguang Zhang <[email protected]>

As the commit message states, a done:

| /* We need at least two pages for this to work. */
| if (nr_pages < 2)
| return NULL;

... so this looks sensible to me:

Acked-by: Mark Rutland <[email protected]>

Mark.

> ---
> drivers/perf/arm_spe_pmu.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/perf/arm_spe_pmu.c b/drivers/perf/arm_spe_pmu.c
> index 4e4984a..b72c048 100644
> --- a/drivers/perf/arm_spe_pmu.c
> +++ b/drivers/perf/arm_spe_pmu.c
> @@ -831,7 +831,7 @@ static void *arm_spe_pmu_setup_aux(struct perf_event *event, void **pages,
> * parts and give userspace a fighting chance of getting some
> * useful data out of it.
> */
> - if (!nr_pages || (snapshot && (nr_pages & 1)))
> + if (snapshot && (nr_pages & 1))
> return NULL;
>
> if (cpu == -1)
> --
> 1.8.3.1
>