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From: Deepak R Varma <drv@mailo.com>
To: Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Jiri Olsa <jolsa@kernel.org>, Namhyung Kim <namhyung@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: Saurabh Singh Sengar <ssengar@microsoft.com>,
	Praveen Kumar <kumarpraveen@linux.microsoft.com>,
	Deepak R Varma <drv@mailo.com>
Subject: [PATCH] perf/x86/amd/core: Use sysfs_emit() in show() callback function
Date: Fri, 17 Feb 2023 22:12:57 +0530	[thread overview]
Message-ID: <Y++ukV1djYTd01vy@ubun2204.myguest.virtualbox.org> (raw)

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(-)

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);
-- 
2.34.1




             reply	other threads:[~2023-02-17 16:43 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-02-17 16:42 Deepak R Varma [this message]
2023-02-20 11:37 ` [PATCH] perf/x86/amd/core: Use sysfs_emit() in show() callback function Peter Zijlstra

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