[PATCH v2 1/2] fs/resctrl: Avoid extra call to strlen() in schemata_list_add()

[PATCH v2 1/2] fs/resctrl: Avoid extra call to strlen() in schemata_list_add()

[Dmitry Antipov]

After passing an overflow check, it's safe to assume that snprintf()
returns the number of characters emitted. So drop the unnecessary
call to strlen().

Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
---
v2: adjust title and commit message (Reinette)
---
 fs/resctrl/rdtgroup.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index 5dcbb0a964e8..68be9b903ac6 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -2858,7 +2858,7 @@ static int schemata_list_add(struct rdt_resource *r, enum resctrl_conf_type type
 {
 	struct resctrl_schema *s;
 	const char *suffix = "";
-	int ret, cl;
+	int cl;
 
 	s = kzalloc_obj(*s);
 	if (!s)
@@ -2882,14 +2882,12 @@ static int schemata_list_add(struct rdt_resource *r, enum resctrl_conf_type type
 		break;
 	}
 
-	ret = snprintf(s->name, sizeof(s->name), "%s%s", r->name, suffix);
-	if (ret >= sizeof(s->name)) {
+	cl = snprintf(s->name, sizeof(s->name), "%s%s", r->name, suffix);
+	if (cl >= sizeof(s->name)) {
 		kfree(s);
 		return -EINVAL;
 	}
 
-	cl = strlen(s->name);
-
 	/*
 	 * If CDP is supported by this resource, but not enabled,
 	 * include the suffix. This ensures the tabular format of the
-- 
2.55.0

[PATCH v2 2/2] fs/resctrl: Simplify pseudo_lock_measure_trigger()

[Dmitry Antipov]

Use convenient kstrtoint_from_user() to simplify pseudo_lock_measure_trigger().

Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
---
v2: adjust title and commit message (Reinette)
---
 fs/resctrl/pseudo_lock.c | 9 +--------
 1 file changed, 1 insertion(+), 8 deletions(-)

diff --git a/fs/resctrl/pseudo_lock.c b/fs/resctrl/pseudo_lock.c
index dea2b4bf966f..56ab63f19bad 100644
--- a/fs/resctrl/pseudo_lock.c
+++ b/fs/resctrl/pseudo_lock.c
@@ -750,17 +750,10 @@ static ssize_t pseudo_lock_measure_trigger(struct file *file,
 					   size_t count, loff_t *ppos)
 {
 	struct rdtgroup *rdtgrp = file->private_data;
-	size_t buf_size;
-	char buf[32];
 	int ret;
 	int sel;
 
-	buf_size = min(count, (sizeof(buf) - 1));
-	if (copy_from_user(buf, user_buf, buf_size))
-		return -EFAULT;
-
-	buf[buf_size] = '\0';
-	ret = kstrtoint(buf, 10, &sel);
+	ret = kstrtoint_from_user(user_buf, count, 10, &sel);
 	if (ret == 0) {
 		if (sel != 1 && sel != 2 && sel != 3)
 			return -EINVAL;
-- 
2.55.0

Re: [PATCH v2 1/2] fs/resctrl: Avoid extra call to strlen() in schemata_list_add()

[Reinette Chatre]

Hi Dmitry,

On 8/21/26 1:11 AM, Dmitry Antipov wrote:
> After passing an overflow check, it's safe to assume that snprintf()
> returns the number of characters emitted. So drop the unnecessary
> call to strlen().
> 
> Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
> ---
Thank you.

Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>

Reinette

Re: [PATCH v2 2/2] fs/resctrl: Simplify pseudo_lock_measure_trigger()

[Reinette Chatre]

Hi Dmitry,

On 8/21/26 1:11 AM, Dmitry Antipov wrote:
> Use convenient kstrtoint_from_user() to simplify pseudo_lock_measure_trigger().
> 
> Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
> ---
Thank you.

Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>

Reinette

Re: [PATCH v2 1/2] fs/resctrl: Avoid extra call to strlen() in schemata_list_add()

[Reinette Chatre]

Dear x86 maintainers,

Could you please consider both cleanups in this series for inclusion?

Thank you very much.

Reinette

On 8/21/26 1:11 AM, Dmitry Antipov wrote:
> After passing an overflow check, it's safe to assume that snprintf()
> returns the number of characters emitted. So drop the unnecessary
> call to strlen().
> 
> Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
> ---
> v2: adjust title and commit message (Reinette)
> ---
>  fs/resctrl/rdtgroup.c | 8 +++-----
>  1 file changed, 3 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
> index 5dcbb0a964e8..68be9b903ac6 100644
> --- a/fs/resctrl/rdtgroup.c
> +++ b/fs/resctrl/rdtgroup.c
> @@ -2858,7 +2858,7 @@ static int schemata_list_add(struct rdt_resource *r, enum resctrl_conf_type type
>  {
>  	struct resctrl_schema *s;
>  	const char *suffix = "";
> -	int ret, cl;
> +	int cl;
>  
>  	s = kzalloc_obj(*s);
>  	if (!s)
> @@ -2882,14 +2882,12 @@ static int schemata_list_add(struct rdt_resource *r, enum resctrl_conf_type type
>  		break;
>  	}
>  
> -	ret = snprintf(s->name, sizeof(s->name), "%s%s", r->name, suffix);
> -	if (ret >= sizeof(s->name)) {
> +	cl = snprintf(s->name, sizeof(s->name), "%s%s", r->name, suffix);
> +	if (cl >= sizeof(s->name)) {
>  		kfree(s);
>  		return -EINVAL;
>  	}
>  
> -	cl = strlen(s->name);
> -
>  	/*
>  	 * If CDP is supported by this resource, but not enabled,
>  	 * include the suffix. This ensures the tabular format of the

Re: [PATCH v2 1/2] fs/resctrl: Avoid extra call to strlen() in schemata_list_add()

[Borislav Petkov]

On Thu, Sep 03, 2026 at 08:42:47AM -0700, Reinette Chatre wrote:
> Dear x86 maintainers,
> 
> Could you please consider both cleanups in this series for inclusion?

I see Sashiko is complaining about two pre-existing issues:

https://sashiko.dev/#/patchset/20260821081128.19242-1-dmantipov%40yandex.ru

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

Re: [PATCH v2 1/2] fs/resctrl: Avoid extra call to strlen() in schemata_list_add()

[Reinette Chatre]

Hi Boris,

On 9/17/26 8:54 AM, Borislav Petkov wrote:
> On Thu, Sep 03, 2026 at 08:42:47AM -0700, Reinette Chatre wrote:
>> Dear x86 maintainers,
>>
>> Could you please consider both cleanups in this series for inclusion?
> 
> I see Sashiko is complaining about two pre-existing issues:
> 
> https://sashiko.dev/#/patchset/20260821081128.19242-1-dmantipov%40yandex.ru
> 

These same pseudo-locking related issues were reported by Sashiko during a previous
resctrl submission:

	https://sashiko.dev/#/patchset/20260515193944.15114-1-tony.luck%40intel.com

There was an effort to address these issues, latest attempt can be seen at: 

	https://lore.kernel.org/lkml/cover.1779476724.git.reinette.chatre@intel.com/

These attempts at fixes just exposed more corner cases related to pseudo-locking, for example:

	https://lore.kernel.org/all/e40a924f-5398-43bd-821a-2ff9873c5a4c@intel.com/

All of these issues are related to intricate races that could be triggered by user space stress
of the pseudo-locking files that is only possible on very specific ten-year old hardware.
Since such usage is contrary to the pseudo-locking usage model which requires care by default
I decided to drop that work.

Reinette

Re: [PATCH v2 1/2] fs/resctrl: Avoid extra call to strlen() in schemata_list_add()

[Borislav Petkov]

On Thu, Sep 17, 2026 at 09:17:23AM -0700, Reinette Chatre wrote:
> Hi Boris,
> 
> On 9/17/26 8:54 AM, Borislav Petkov wrote:
> > On Thu, Sep 03, 2026 at 08:42:47AM -0700, Reinette Chatre wrote:
> >> Dear x86 maintainers,
> >>
> >> Could you please consider both cleanups in this series for inclusion?
> > 
> > I see Sashiko is complaining about two pre-existing issues:
> > 
> > https://sashiko.dev/#/patchset/20260821081128.19242-1-dmantipov%40yandex.ru
> > 
> 
> These same pseudo-locking related issues were reported by Sashiko during a previous
> resctrl submission:
> 
> 	https://sashiko.dev/#/patchset/20260515193944.15114-1-tony.luck%40intel.com
> 
> There was an effort to address these issues, latest attempt can be seen at: 
> 
> 	https://lore.kernel.org/lkml/cover.1779476724.git.reinette.chatre@intel.com/
> 
> These attempts at fixes just exposed more corner cases related to pseudo-locking, for example:
> 
> 	https://lore.kernel.org/all/e40a924f-5398-43bd-821a-2ff9873c5a4c@intel.com/
> 
> All of these issues are related to intricate races that could be triggered by user space stress
> of the pseudo-locking files that is only possible on very specific ten-year old hardware.
> Since such usage is contrary to the pseudo-locking usage model which requires care by default
> I decided to drop that work.

Thanks, we probably should start tracking all those Sashiko complaints which
we're not going to address.

/me notes these links.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

[tip: x86/cache] fs/resctrl: Simplify pseudo_lock_measure_trigger()

[tip-bot2 for Dmitry Antipov]

The following commit has been merged into the x86/cache branch of tip:

Commit-ID:     a3f5e6eba41885dcffb635b54d6c4a18aa579cd5
Gitweb:        https://git.kernel.org/tip/a3f5e6eba41885dcffb635b54d6c4a18aa579cd5
Author:        Dmitry Antipov <dmantipov@yandex.ru>
AuthorDate:    Fri, 21 Aug 2026 11:11:28 +03:00
Committer:     Borislav Petkov (AMD) <bp@alien8.de>
CommitterDate: Thu, 17 Sep 2026 12:08:47 -07:00

fs/resctrl: Simplify pseudo_lock_measure_trigger()

Use convenient kstrtoint_from_user() to simplify pseudo_lock_measure_trigger().

No functional changes.

Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://patch.msgid.link/20260821081128.19242-2-dmantipov@yandex.ru
---
 fs/resctrl/pseudo_lock.c |  9 +--------
 1 file changed, 1 insertion(+), 8 deletions(-)

diff --git a/fs/resctrl/pseudo_lock.c b/fs/resctrl/pseudo_lock.c
index dea2b4b..56ab63f 100644
--- a/fs/resctrl/pseudo_lock.c
+++ b/fs/resctrl/pseudo_lock.c
@@ -750,17 +750,10 @@ static ssize_t pseudo_lock_measure_trigger(struct file *file,
 					   size_t count, loff_t *ppos)
 {
 	struct rdtgroup *rdtgrp = file->private_data;
-	size_t buf_size;
-	char buf[32];
 	int ret;
 	int sel;
 
-	buf_size = min(count, (sizeof(buf) - 1));
-	if (copy_from_user(buf, user_buf, buf_size))
-		return -EFAULT;
-
-	buf[buf_size] = '\0';
-	ret = kstrtoint(buf, 10, &sel);
+	ret = kstrtoint_from_user(user_buf, count, 10, &sel);
 	if (ret == 0) {
 		if (sel != 1 && sel != 2 && sel != 3)
 			return -EINVAL;

[tip: x86/cache] fs/resctrl: Avoid extra call to strlen() in schemata_list_add()

[tip-bot2 for Dmitry Antipov]

The following commit has been merged into the x86/cache branch of tip:

Commit-ID:     4b31656d917c46c6d9f874162ede4f54b2a5959f
Gitweb:        https://git.kernel.org/tip/4b31656d917c46c6d9f874162ede4f54b2a5959f
Author:        Dmitry Antipov <dmantipov@yandex.ru>
AuthorDate:    Fri, 21 Aug 2026 11:11:27 +03:00
Committer:     Borislav Petkov (AMD) <bp@alien8.de>
CommitterDate: Thu, 17 Sep 2026 10:41:53 -07:00

fs/resctrl: Avoid extra call to strlen() in schemata_list_add()

After passing an overflow check, it's safe to assume that snprintf()
returns the number of characters emitted. So drop the unnecessary
call to strlen().

Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Link: https://patch.msgid.link/20260821081128.19242-1-dmantipov@yandex.ru
---
 fs/resctrl/rdtgroup.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index 5dcbb0a..68be9b9 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -2858,7 +2858,7 @@ static int schemata_list_add(struct rdt_resource *r, enum resctrl_conf_type type
 {
 	struct resctrl_schema *s;
 	const char *suffix = "";
-	int ret, cl;
+	int cl;
 
 	s = kzalloc_obj(*s);
 	if (!s)
@@ -2882,14 +2882,12 @@ static int schemata_list_add(struct rdt_resource *r, enum resctrl_conf_type type
 		break;
 	}
 
-	ret = snprintf(s->name, sizeof(s->name), "%s%s", r->name, suffix);
-	if (ret >= sizeof(s->name)) {
+	cl = snprintf(s->name, sizeof(s->name), "%s%s", r->name, suffix);
+	if (cl >= sizeof(s->name)) {
 		kfree(s);
 		return -EINVAL;
 	}
 
-	cl = strlen(s->name);
-
 	/*
 	 * If CDP is supported by this resource, but not enabled,
 	 * include the suffix. This ensures the tabular format of the