From: Sumeet Pawnikar <sumeet4linux@gmail.com>
To: rafael@kernel.org, linux-pm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, sumeet4linux@gmail.com
Subject: [PATCH] powercap: sscanf return value error handling
Date: Sun, 7 Dec 2025 20:45:48 +0530 [thread overview]
Message-ID: <20251207151549.202452-1-sumeet4linux@gmail.com> (raw)
Inconsistent error handling for sscanf() return value check.
It uses implicit boolean conversion instead of explicit return
value check. The code checks if (!sscanf(...)) which is incorrect
because:
1. sscanf returns the number of successfully parsed items
2. On success, it returns 1 (one item passed)
3. On failure, it returns 0 or EOF
4. The check 'if (!sscanf(...))' is wrong because it treats
success (1) as failure
All occurrences of sscanf() now uses explicit return value check.
With this behavior it returns '-EINVAL' when parsing fails (returns
0 or EOF), and continues when parsing succeeds (returns 1).
Signed-off-by: Sumeet Pawnikar <sumeet4linux@gmail.com>
---
drivers/powercap/powercap_sys.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/powercap/powercap_sys.c b/drivers/powercap/powercap_sys.c
index bdc65e040d17..e998454e4bf6 100644
--- a/drivers/powercap/powercap_sys.c
+++ b/drivers/powercap/powercap_sys.c
@@ -68,7 +68,7 @@ static ssize_t show_constraint_##_attr(struct device *dev, \
int id; \
struct powercap_zone_constraint *pconst;\
\
- if (!sscanf(dev_attr->attr.name, "constraint_%d_", &id)) \
+ if (sscanf(dev_attr->attr.name, "constraint_%d_", &id) != 1) \
return -EINVAL; \
if (id >= power_zone->const_id_cnt) \
return -EINVAL; \
@@ -93,7 +93,7 @@ static ssize_t store_constraint_##_attr(struct device *dev,\
int id; \
struct powercap_zone_constraint *pconst;\
\
- if (!sscanf(dev_attr->attr.name, "constraint_%d_", &id)) \
+ if (sscanf(dev_attr->attr.name, "constraint_%d_", &id) != 1) \
return -EINVAL; \
if (id >= power_zone->const_id_cnt) \
return -EINVAL; \
@@ -162,7 +162,7 @@ static ssize_t show_constraint_name(struct device *dev,
ssize_t len = -ENODATA;
struct powercap_zone_constraint *pconst;
- if (!sscanf(dev_attr->attr.name, "constraint_%d_", &id))
+ if (sscanf(dev_attr->attr.name, "constraint_%d_", &id) != 1)
return -EINVAL;
if (id >= power_zone->const_id_cnt)
return -EINVAL;
--
2.43.0
next reply other threads:[~2025-12-07 15:16 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-12-07 15:15 Sumeet Pawnikar [this message]
2025-12-15 11:34 ` [PATCH] powercap: sscanf return value error handling Rafael J. Wysocki
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