diff mbox series

perf/x86/amd/core: Use sysfs_emit() in show() callback function

Message ID Y++ukV1djYTd01vy@ubun2204.myguest.virtualbox.org
State New
Headers
Series perf/x86/amd/core: Use sysfs_emit() in show() callback function |

Commit Message

Deepak R Varma Feb. 17, 2023, 4:42 p.m. UTC 
  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/amd/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Peter Zijlstra Feb. 20, 2023, 11:37 a.m. UTC | #1 
On Fri, Feb 17, 2023 at 10:12:57PM +0530, Deepak R Varma wrote:
> 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.

This Changelog fails to inform me of what the actual problem is and why
the proposed solution is better.

As such I cannot form an opinion on the patch and must decline.

(Also, I'm not going to chase down random links on the interweb,
Changelogs should be self contained)
diff mbox series

Patch

diff --git a/arch/x86/events/amd/core.c b/arch/x86/events/amd/core.c
index 4386b10682ce..47a3a841332a 100644
--- a/arch/x86/events/amd/core.c
+++ b/arch/x86/events/amd/core.c
@@ -1272,7 +1272,7 @@  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);