linux-kernel - [PATCH v2 2/4] arch/x86/events/core: Convert sprintf/snprintf to sysfs

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Date: Fri, 26 Jan 2024 14:13:17 +0800
From: Li Zhijian <lizhijian@...itsu.com>
To: linux-kernel@...r.kernel.org
Cc: Li Zhijian <lizhijian@...itsu.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Ian Rogers <irogers@...gle.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	x86@...nel.org,
	"H. Peter Anvin" <hpa@...or.com>,
	linux-perf-users@...r.kernel.org
Subject: [PATCH v2 2/4] arch/x86/events/core: Convert sprintf/snprintf to sysfs_emit

Per filesystems/sysfs.rst, show() should only use sysfs_emit()
or sysfs_emit_at() when formatting the value to be returned to user space.

coccinelle complains that there are still a couple of functions that use
snprintf(). Convert them to sysfs_emit().

> ./arch/x86/events/core.c:1895:11-19: WARNING: please use sysfs_emit
                           ^^^^^ this one cannot convert to sysfs_emit
                                 where it intends to print a sub-string.

> ./arch/x86/events/core.c:2542:8-16: WARNING: please use sysfs_emit
> ./arch/x86/events/core.c:2600:8-16: WARNING: please use sysfs_emit

Most of this patch is generated by:
$ make coccicheck MODE=patch COCCI=scripts/coccinelle/api/device_attr_show.cocci M=arch/x86/events/core.c | sed -n '6,$p' | patch -p1

No functional change intended

CC: Peter Zijlstra <peterz@...radead.org>
CC: Ingo Molnar <mingo@...hat.com>
CC: Arnaldo Carvalho de Melo <acme@...nel.org>
CC: Mark Rutland <mark.rutland@....com>
CC: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
CC: Jiri Olsa <jolsa@...nel.org>
CC: Namhyung Kim <namhyung@...nel.org>
CC: Ian Rogers <irogers@...gle.com>
CC: Adrian Hunter <adrian.hunter@...el.com>
CC: Thomas Gleixner <tglx@...utronix.de>
CC: Borislav Petkov <bp@...en8.de>
CC: Dave Hansen <dave.hansen@...ux.intel.com>
CC: x86@...nel.org
CC: "H. Peter Anvin" <hpa@...or.com>
CC: linux-perf-users@...r.kernel.org
Signed-off-by: Li Zhijian <lizhijian@...itsu.com>
---
V2:
- Address Adrian's comment:
  leave "snprintf(page, next_str - str + 1, "%s", str)" alone, it
  intends to print a sub-string, that cannot covert to sysfs_emit simply.
-
V2: extract patch from the patch set[1] so that maintainer accept it separately.
[1] https://lore.kernel.org/lkml/20240116041129.3937800-1-lizhijian@fujitsu.com/
Signed-off-by: Li Zhijian <lizhijian@...itsu.com>
---
 arch/x86/events/core.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index 09050641ce5d..20d963196e4c 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -1832,7 +1832,7 @@ ssize_t events_sysfs_show(struct device *dev, struct device_attribute *attr, cha
 
 	/* string trumps id */
 	if (pmu_attr->event_str)
-		return sprintf(page, "%s\n", pmu_attr->event_str);
+		return sysfs_emit(page, "%s\n", pmu_attr->event_str);
 
 	return x86_pmu.events_sysfs_show(page, config);
 }
@@ -1855,7 +1855,7 @@ ssize_t events_ht_sysfs_show(struct device *dev, struct device_attribute *attr,
 	 * if they are owned by some other guest.  The user tool
 	 * has to re-read when a thread sibling gets onlined later.
 	 */
-	return sprintf(page, "%s",
+	return sysfs_emit(page, "%s",
 			topology_max_smt_threads() > 1 ?
 			pmu_attr->event_str_ht :
 			pmu_attr->event_str_noht);
@@ -1872,7 +1872,7 @@ ssize_t events_hybrid_sysfs_show(struct device *dev,
 	int i;
 
 	if (hweight64(pmu_attr->pmu_type) == 1)
-		return sprintf(page, "%s", pmu_attr->event_str);
+		return sysfs_emit(page, "%s", pmu_attr->event_str);
 
 	/*
 	 * Hybrid PMUs may support the same event name, but with different
@@ -1894,7 +1894,7 @@ ssize_t events_hybrid_sysfs_show(struct device *dev,
 			if (next_str)
 				return snprintf(page, next_str - str + 1, "%s", str);
 			else
-				return sprintf(page, "%s", str);
+				return sysfs_emit(page, "%s", str);
 		}
 		str = strchr(str, ';');
 		str++;
@@ -2539,7 +2539,7 @@ static ssize_t get_attr_rdpmc(struct device *cdev,
 			      struct device_attribute *attr,
 			      char *buf)
 {
-	return snprintf(buf, 40, "%d\n", x86_pmu.attr_rdpmc);
+	return sysfs_emit(buf, "%d\n", x86_pmu.attr_rdpmc);
 }
 
 static ssize_t set_attr_rdpmc(struct device *cdev,
@@ -2597,7 +2597,7 @@ static ssize_t max_precise_show(struct device *cdev,
 				  struct device_attribute *attr,
 				  char *buf)
 {
-	return snprintf(buf, PAGE_SIZE, "%d\n", x86_pmu_max_precise());
+	return sysfs_emit(buf, "%d\n", x86_pmu_max_precise());
 }
 
 static DEVICE_ATTR_RO(max_precise);
-- 
2.29.2