2023-10-21 14:43:02

by Christophe JAILLET

Subject: [PATCH] tracing/histograms: Simplify last_cmd_set()

Turn a kzalloc()+strcpy()+strncat() into an equivalent and less verbose
kasprintf().

Signed-off-by: Christophe JAILLET <[email protected]>
---
kernel/trace/trace_events_hist.c | 11 ++---------
1 file changed, 2 insertions(+), 9 deletions(-)

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index d06938ae0717..1abc07fba1b9 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -774,23 +774,16 @@ static void last_cmd_set(struct trace_event_file *file, char *str)
{
const char *system = NULL, *name = NULL;
struct trace_event_call *call;
- int len;

if (!str)
return;

- /* sizeof() contains the nul byte */
- len = sizeof(HIST_PREFIX) + strlen(str);
kfree(last_cmd);
- last_cmd = kzalloc(len, GFP_KERNEL);
+
+ last_cmd = kasprintf(GFP_KERNEL, HIST_PREFIX "%s", str);
if (!last_cmd)
return;

- strcpy(last_cmd, HIST_PREFIX);
- /* Again, sizeof() contains the nul byte */
- len -= sizeof(HIST_PREFIX);
- strncat(last_cmd, str, len);
-
if (file) {
call = file->event_call;
system = call->class->system;
--
2.34.1

2023-10-23 10:09:21

by Mukesh Ojha

Subject: Re: [PATCH] tracing/histograms: Simplify last_cmd_set()

On 10/21/2023 8:12 PM, Christophe JAILLET wrote:
> Turn a kzalloc()+strcpy()+strncat() into an equivalent and less verbose
> kasprintf().
>
> Signed-off-by: Christophe JAILLET <[email protected]>
> ---
> kernel/trace/trace_events_hist.c | 11 ++---------
> 1 file changed, 2 insertions(+), 9 deletions(-)
>
> diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
> index d06938ae0717..1abc07fba1b9 100644
> --- a/kernel/trace/trace_events_hist.c
> +++ b/kernel/trace/trace_events_hist.c
> @@ -774,23 +774,16 @@ static void last_cmd_set(struct trace_event_file *file, char *str)
> {
> const char *system = NULL, *name = NULL;
> struct trace_event_call *call;
> - int len;
>
> if (!str)
> return;
>
> - /* sizeof() contains the nul byte */
> - len = sizeof(HIST_PREFIX) + strlen(str);
> kfree(last_cmd);
> - last_cmd = kzalloc(len, GFP_KERNEL);
> +
> + last_cmd = kasprintf(GFP_KERNEL, HIST_PREFIX "%s", str);
> if (!last_cmd)
> return;
>
> - strcpy(last_cmd, HIST_PREFIX);
> - /* Again, sizeof() contains the nul byte */
> - len -= sizeof(HIST_PREFIX);
> - strncat(last_cmd, str, len);

LGTM, careful optimization., Thanks.
Reviewed-by: Mukesh ojha <[email protected]>


-Mukesh

> -
> if (file) {
> call = file->event_call;
> system = call->class->system;