bpf: Replace snprintf("%s", ...) with strscpy()

[PATCH bpf-next] bpf: Replace snprintf("%s", ...) with strscpy()

Posted by Thorsten Blum 5 days, 18 hours ago

Replace snprintf("%s", ...) with the faster and more direct strscpy().

Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
---
 kernel/bpf/btf.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 8959f3bc1e92..72fa0cb1a71b 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -25,6 +25,7 @@
 #include <linux/perf_event.h>
 #include <linux/bsearch.h>
 #include <linux/kobject.h>
+#include <linux/string.h>
 #include <linux/sysfs.h>
 #include <linux/overflow.h>
 
@@ -1210,8 +1211,7 @@ static const char *btf_show_name(struct btf_show *show)
 
 	/* Even if we don't want type name info, we want parentheses etc */
 	if (show->flags & BTF_SHOW_NONAME)
-		snprintf(show->state.name, sizeof(show->state.name), "%s",
-			 parens);
+		strscpy(show->state.name, parens);
 	else
 		snprintf(show->state.name, sizeof(show->state.name),
 			 "%s%s%s(%s%s%s%s%s%s)%s",
@@ -6324,7 +6324,7 @@ static struct btf *btf_parse_base(struct btf_verifier_env *env, const char *name
 	btf->data_size = data_size;
 	btf->kernel_btf = true;
 	btf->named_start_id = 0;
-	snprintf(btf->name, sizeof(btf->name), "%s", name);
+	strscpy(btf->name, name);
 
 	err = btf_parse_hdr(env);
 	if (err)
@@ -6443,7 +6443,7 @@ static struct btf *btf_parse_module(const char *module_name, const void *data,
 	btf->start_str_off = base_btf->hdr.str_len;
 	btf->kernel_btf = true;
 	btf->named_start_id = 0;
-	snprintf(btf->name, sizeof(btf->name), "%s", module_name);
+	strscpy(btf->name, module_name);
 
 	btf->data = kvmemdup(data, data_size, GFP_KERNEL | __GFP_NOWARN);
 	if (!btf->data) {
-- 
Thorsten Blum <thorsten.blum@linux.dev>
GPG: 1D60 735E 8AEF 3BE4 73B6  9D84 7336 78FD 8DFE EAD4

Re: [PATCH bpf-next] bpf: Replace snprintf("%s", ...) with strscpy()

Posted by Alexei Starovoitov 5 days, 16 hours ago

On Sun, Feb 1, 2026 at 10:06 AM Thorsten Blum <thorsten.blum@linux.dev> wrote:
>
> Replace snprintf("%s", ...) with the faster and more direct strscpy().
>
> Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
> ---
>  kernel/bpf/btf.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
> index 8959f3bc1e92..72fa0cb1a71b 100644
> --- a/kernel/bpf/btf.c
> +++ b/kernel/bpf/btf.c
> @@ -25,6 +25,7 @@
>  #include <linux/perf_event.h>
>  #include <linux/bsearch.h>
>  #include <linux/kobject.h>
> +#include <linux/string.h>
>  #include <linux/sysfs.h>
>  #include <linux/overflow.h>
>
> @@ -1210,8 +1211,7 @@ static const char *btf_show_name(struct btf_show *show)
>
>         /* Even if we don't want type name info, we want parentheses etc */
>         if (show->flags & BTF_SHOW_NONAME)
> -               snprintf(show->state.name, sizeof(show->state.name), "%s",
> -                        parens);
> +               strscpy(show->state.name, parens);
>         else
>                 snprintf(show->state.name, sizeof(show->state.name),
>                          "%s%s%s(%s%s%s%s%s%s)%s",

I prefer to keep snprintf here for symmetry with the above.

> @@ -6324,7 +6324,7 @@ static struct btf *btf_parse_base(struct btf_verifier_env *env, const char *name
>         btf->data_size = data_size;
>         btf->kernel_btf = true;
>         btf->named_start_id = 0;
> -       snprintf(btf->name, sizeof(btf->name), "%s", name);
> +       strscpy(btf->name, name);
>
>         err = btf_parse_hdr(env);
>         if (err)
> @@ -6443,7 +6443,7 @@ static struct btf *btf_parse_module(const char *module_name, const void *data,
>         btf->start_str_off = base_btf->hdr.str_len;
>         btf->kernel_btf = true;
>         btf->named_start_id = 0;
> -       snprintf(btf->name, sizeof(btf->name), "%s", module_name);
> +       strscpy(btf->name, module_name);

These two are fine.

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