2021-05-07 14:02:43

by Jiapeng Chong

Subject: [PATCH] tracing: Remove redundant assignment to event_var

Variable event_var is set to 'ERR_PTR(-EINVAL)', but this value
is never read as it is overwritten or not used later on, hence
it is a redundant assignment and can be removed.

Clean up the following clang-analyzer warning:

kernel/trace/trace_events_hist.c:2437:21: warning: Value stored to
'event_var' during its initialization is never read
[clang-analyzer-deadcode.DeadStores].

Reported-by: Abaci Robot <[email protected]>
Signed-off-by: Jiapeng Chong <[email protected]>
---
kernel/trace/trace_events_hist.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index c1abd63..b37342c 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -2434,7 +2434,7 @@ static struct trace_event_file *event_file(struct trace_array *tr,
char *subsys_name, char *event_name, char *field_name)
{
struct trace_array *tr = target_hist_data->event_file->tr;
- struct hist_field *event_var = ERR_PTR(-EINVAL);
+ struct hist_field *event_var;
struct hist_trigger_data *hist_data;
unsigned int i, n, first = true;
struct field_var_hist *var_hist;
--
1.8.3.1

2021-05-07 17:06:22

by Steven Rostedt

Subject: Re: [PATCH] tracing: Remove redundant assignment to event_var

On Fri, 7 May 2021 18:23:50 +0800
Jiapeng Chong <[email protected]> wrote:

> Variable event_var is set to 'ERR_PTR(-EINVAL)', but this value
> is never read as it is overwritten or not used later on, hence
> it is a redundant assignment and can be removed.
>
> Clean up the following clang-analyzer warning:
>
> kernel/trace/trace_events_hist.c:2437:21: warning: Value stored to
> 'event_var' during its initialization is never read
> [clang-analyzer-deadcode.DeadStores].
>
> Reported-by: Abaci Robot <[email protected]>
> Signed-off-by: Jiapeng Chong <[email protected]>
> ---
> kernel/trace/trace_events_hist.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
> index c1abd63..b37342c 100644
> --- a/kernel/trace/trace_events_hist.c
> +++ b/kernel/trace/trace_events_hist.c
> @@ -2434,7 +2434,7 @@ static struct trace_event_file *event_file(struct trace_array *tr,
> char *subsys_name, char *event_name, char *field_name)
> {
> struct trace_array *tr = target_hist_data->event_file->tr;
> - struct hist_field *event_var = ERR_PTR(-EINVAL);
> + struct hist_field *event_var;
> struct hist_trigger_data *hist_data;
> unsigned int i, n, first = true;
> struct field_var_hist *var_hist;

Thanks, but if you are going to make this change, please move the
declaration of event_var below (or above) key_field, as their names are
both the same size in length and are of the same type. This keeps the
"upside-down x-mas tree" look of the declarations.

-- Steve