2024-02-25 16:47:57

by Thorsten Blum

Subject: [PATCH] tracing: Use div64_u64() instead of do_div()

Fixes Coccinelle/coccicheck warnings reported by do_div.cocci.

Compared to do_div(), div64_u64() does not implicitly cast the divisor and
does not unnecessarily calculate the remainder.

Signed-off-by: Thorsten Blum <[email protected]>
---
kernel/trace/trace_benchmark.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/kernel/trace/trace_benchmark.c b/kernel/trace/trace_benchmark.c
index 54d5fa35c90a..811b08439406 100644
--- a/kernel/trace/trace_benchmark.c
+++ b/kernel/trace/trace_benchmark.c
@@ -92,7 +92,6 @@ static void trace_do_benchmark(void)
bm_total += delta;
bm_totalsq += delta * delta;

-
if (bm_cnt > 1) {
/*
* Apply Welford's method to calculate standard deviation:
@@ -105,7 +104,7 @@ static void trace_do_benchmark(void)
stddev = 0;

delta = bm_total;
- do_div(delta, bm_cnt);
+ delta = div64_u64(delta, bm_cnt);
avg = delta;

if (stddev > 0) {
@@ -127,7 +126,7 @@ static void trace_do_benchmark(void)
seed = stddev;
if (!last_seed)
break;
- do_div(seed, last_seed);
+ seed = div64_u64(seed, last_seed);
seed += last_seed;
do_div(seed, 2);
} while (i++ < 10 && last_seed != seed);
--
2.43.2

2024-02-25 22:21:50

by Masami Hiramatsu

Subject: Re: [PATCH] tracing: Use div64_u64() instead of do_div()

On Sun, 25 Feb 2024 17:45:08 +0100
Thorsten Blum <[email protected]> wrote:

> Fixes Coccinelle/coccicheck warnings reported by do_div.cocci.
>
> Compared to do_div(), div64_u64() does not implicitly cast the divisor and
> does not unnecessarily calculate the remainder.
>

Looks good to me.

Acked-by: Masami Hiramatsu (Google) <[email protected]>

Thanks!

> Signed-off-by: Thorsten Blum <[email protected]>
> ---
> kernel/trace/trace_benchmark.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/trace/trace_benchmark.c b/kernel/trace/trace_benchmark.c
> index 54d5fa35c90a..811b08439406 100644
> --- a/kernel/trace/trace_benchmark.c
> +++ b/kernel/trace/trace_benchmark.c
> @@ -92,7 +92,6 @@ static void trace_do_benchmark(void)
> bm_total += delta;
> bm_totalsq += delta * delta;
>
> -
> if (bm_cnt > 1) {
> /*
> * Apply Welford's method to calculate standard deviation:
> @@ -105,7 +104,7 @@ static void trace_do_benchmark(void)
> stddev = 0;
>
> delta = bm_total;
> - do_div(delta, bm_cnt);
> + delta = div64_u64(delta, bm_cnt);
> avg = delta;
>
> if (stddev > 0) {
> @@ -127,7 +126,7 @@ static void trace_do_benchmark(void)
> seed = stddev;
> if (!last_seed)
> break;
> - do_div(seed, last_seed);
> + seed = div64_u64(seed, last_seed);
> seed += last_seed;
> do_div(seed, 2);
> } while (i++ < 10 && last_seed != seed);
> --
> 2.43.2
>


--
Masami Hiramatsu (Google) <[email protected]>