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powercap: fix sscanf() error return value handling

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Fix inconsistent error handling for sscanf() return value check.

Implicit boolean conversion is used instead of explicit return
value checks. 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>
[ rjw: Subject and changelog edits ]
Link: https://patch.msgid.link/20251207151549.202452-1-sumeet4linux@gmail.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Sumeet Pawnikar
2025-12-07 20:45:48 +05:30
committed by Rafael J. Wysocki
parent 7bda1910c4
commit efc4c35b74
1 changed files with 3 additions and 3 deletions
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6
drivers/powercap/powercap_sys.c
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@@ -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;