[PATCH 2/3] perf/x86/intel/pt: Use sysfs_emit() in show() callback function

[PATCH 2/3] perf/x86/intel/pt: Use sysfs_emit() in show() callback function

[Deepak R Varma]

Using sprintf/snprintf functions are error prone and suggested to be
replaced by scnprintf/vscnrptintf as outlined in this [1] LWN article.

A more recent recommendation is to use sysfs_emit() or sysfs_emit_at()
as per Documentation/filesystems/sysfs.rst in show() callback function
when formatting values to be returned to user-space. These helper
functions are PAGE_SIZE aware and wrap a safer call to vscnprintf().

[1] https://lwn.net/Articles/69419/

Issue identified using the coccinelle device_attr_show.cocci script.

Signed-off-by: Deepak R Varma <drv@mailo.com>
---
 arch/x86/events/intel/pt.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/events/intel/pt.c b/arch/x86/events/intel/pt.c
index 42a55794004a..d9e6d771b458 100644
--- a/arch/x86/events/intel/pt.c
+++ b/arch/x86/events/intel/pt.c
@@ -96,7 +96,7 @@ static ssize_t pt_cap_show(struct device *cdev,
 		container_of(attr, struct dev_ext_attribute, attr);
 	enum pt_capabilities cap = (long)ea->var;
 
-	return snprintf(buf, PAGE_SIZE, "%x\n", intel_pt_validate_hw_cap(cap));
+	return sysfs_emit(buf, "%x\n", intel_pt_validate_hw_cap(cap));
 }
 
 static struct attribute_group pt_cap_group __ro_after_init = {
-- 
2.34.1

[PATCH 3/3] perf/x86/intel: Use sysfs_emit() in show() callback function

[Deepak R Varma]

Using sprintf/snprintf functions are error prone and suggested to be
replaced by scnprintf/vscnrptintf as outlined in this [1] LWN article.

A more recent recommendation is to use sysfs_emit() or sysfs_emit_at()
as per Documentation/filesystems/sysfs.rst in show() callback function
when formatting values to be returned to user-space. These helper
functions are PAGE_SIZE aware and wrap a safer call to vscnprintf().

[1] https://lwn.net/Articles/69419/

Issue identified using the coccinelle device_attr_show.cocci script.

Signed-off-by: Deepak R Varma <drv@mailo.com>
---
 arch/x86/events/intel/core.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index bafdc2be479a..8fb1225123ef 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -5273,7 +5273,7 @@ static ssize_t show_sysctl_tfa(struct device *cdev,
 			      struct device_attribute *attr,
 			      char *buf)
 {
-	return snprintf(buf, 40, "%d\n", allow_tsx_force_abort);
+	return sysfs_emit(buf, "%d\n", allow_tsx_force_abort);
 }
 
 static ssize_t set_sysctl_tfa(struct device *cdev,
@@ -5307,7 +5307,7 @@ static ssize_t branches_show(struct device *cdev,
 			     struct device_attribute *attr,
 			     char *buf)
 {
-	return snprintf(buf, PAGE_SIZE, "%d\n", x86_pmu.lbr_nr);
+	return sysfs_emit(buf, "%d\n", x86_pmu.lbr_nr);
 }
 
 static DEVICE_ATTR_RO(branches);
@@ -5323,7 +5323,7 @@ static ssize_t pmu_name_show(struct device *cdev,
 			     struct device_attribute *attr,
 			     char *buf)
 {
-	return snprintf(buf, PAGE_SIZE, "%s\n", pmu_name_str);
+	return sysfs_emit(buf, "%s\n", pmu_name_str);
 }
 
 static DEVICE_ATTR_RO(pmu_name);
-- 
2.34.1