2024-02-15 03:06:21

by Thorsten Blum

Subject: [PATCH] synthetic tracing: Fix trace_string() return value

Fix trace_string() by assigning the string length to the return variable
which got lost in commit ddeea494a16f ("tracing/synthetic: Use union
instead of casts") and caused trace_string() to always return 0.

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

diff --git a/kernel/trace/trace_events_synth.c b/kernel/trace/trace_events_synth.c
index e7af286af4f1..c82b401a294d 100644
--- a/kernel/trace/trace_events_synth.c
+++ b/kernel/trace/trace_events_synth.c
@@ -441,8 +441,9 @@ static unsigned int trace_string(struct synth_trace_event *entry,
if (is_dynamic) {
union trace_synth_field *data = &entry->fields[*n_u64];

+ len = fetch_store_strlen((unsigned long)str_val);
data->as_dynamic.offset = struct_size(entry, fields, event->n_u64) + data_size;
- data->as_dynamic.len = fetch_store_strlen((unsigned long)str_val);
+ data->as_dynamic.len = len;

ret = fetch_store_string((unsigned long)str_val, &entry->fields[*n_u64], entry);

--
2.39.2

2024-02-15 13:37:40

by Masami Hiramatsu

Subject: Re: [PATCH] synthetic tracing: Fix trace_string() return value

On Wed, 14 Feb 2024 23:05:56 +0100
Thorsten Blum <[email protected]> wrote:

> Fix trace_string() by assigning the string length to the return variable
> which got lost in commit ddeea494a16f ("tracing/synthetic: Use union
> instead of casts") and caused trace_string() to always return 0.
>

Good catch!

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

Fixes: ddeea494a16f ("tracing/synthetic: Use union instead of casts")
Cc: [email protected]

Thanks!

> Signed-off-by: Thorsten Blum <[email protected]>
> ---
> kernel/trace/trace_events_synth.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/trace/trace_events_synth.c b/kernel/trace/trace_events_synth.c
> index e7af286af4f1..c82b401a294d 100644
> --- a/kernel/trace/trace_events_synth.c
> +++ b/kernel/trace/trace_events_synth.c
> @@ -441,8 +441,9 @@ static unsigned int trace_string(struct synth_trace_event *entry,
> if (is_dynamic) {
> union trace_synth_field *data = &entry->fields[*n_u64];
>
> + len = fetch_store_strlen((unsigned long)str_val);
> data->as_dynamic.offset = struct_size(entry, fields, event->n_u64) + data_size;
> - data->as_dynamic.len = fetch_store_strlen((unsigned long)str_val);
> + data->as_dynamic.len = len;
>
> ret = fetch_store_string((unsigned long)str_val, &entry->fields[*n_u64], entry);
>
> --
> 2.39.2
>


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