Re: [PATCH] drm/i915/perf: remove redundant variable 'taken'

[Christophe JAILLET]

Le 07/10/2022 à 21:53, Colin Ian King a écrit :
> The assignment to variable taken is redundant and so it can be
> removed as well as the variable too.
>
> Cleans up clang-scan build warnings:
> warning: Although the value stored to 'taken' is used in the enclosing
> expression, the value is never actually read from 'taken'
> [deadcode.DeadStores]

Hi,

#define OA_TAKEN(tail, head)	((tail - head) & (OA_BUFFER_SIZE - 1))

So if the result is not used, maybe calling OA_TAKEN() can be removed as 
well?
It looks like a no-op in such a case.

CJ

> Signed-off-by: Colin Ian King <colin.i.king@xxxxxxxxx>
> ---
>   drivers/gpu/drm/i915/i915_perf.c | 6 ++----
>   1 file changed, 2 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_perf.c b/drivers/gpu/drm/i915/i915_perf.c
> index 0defbb43ceea..15816df916c7 100644
> --- a/drivers/gpu/drm/i915/i915_perf.c
> +++ b/drivers/gpu/drm/i915/i915_perf.c
> @@ -656,7 +656,6 @@ static int gen8_append_oa_reports(struct i915_perf_stream *stream,
>   	size_t start_offset = *offset;
>   	unsigned long flags;
>   	u32 head, tail;
> -	u32 taken;
>   	int ret = 0;
>   
>   	if (drm_WARN_ON(&uncore->i915->drm, !stream->enabled))
> @@ -692,7 +691,7 @@ static int gen8_append_oa_reports(struct i915_perf_stream *stream,
>   
>   
>   	for (/* none */;
> -	     (taken = OA_TAKEN(tail, head));
> +	     OA_TAKEN(tail, head);
>   	     head = (head + report_size) & mask) {
>   		u8 *report = oa_buf_base + head;
>   		u32 *report32 = (void *)report;
> @@ -950,7 +949,6 @@ static int gen7_append_oa_reports(struct i915_perf_stream *stream,
>   	size_t start_offset = *offset;
>   	unsigned long flags;
>   	u32 head, tail;
> -	u32 taken;
>   	int ret = 0;
>   
>   	if (drm_WARN_ON(&uncore->i915->drm, !stream->enabled))
> @@ -984,7 +982,7 @@ static int gen7_append_oa_reports(struct i915_perf_stream *stream,
>   
>   
>   	for (/* none */;
> -	     (taken = OA_TAKEN(tail, head));
> +	     OA_TAKEN(tail, head);
>   	     head = (head + report_size) & mask) {
>   		u8 *report = oa_buf_base + head;
>   		u32 *report32 = (void *)report;