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panic: sys_info: capture si_bits_global before iterating over it

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Patch series "panic: sys_info: Refactor and fix a potential issue", v3.

While targeting the compilation issue due to dangling variable, I have
noticed more opportunities for refactoring that helps to avoid above
mentioned compilation issue in a cleaner way and also fixes a potential
problem with global variable access.


This patch (of 6):

The for-loop might re-read the content of the memory the si_bits_global
points to on each iteration.  Instead, just capture it for the sake of
consistency and use that instead.

Link: https://lkml.kernel.org/r/20251030132007.3742368-1-andriy.shevchenko@linux.intel.com
Link: https://lkml.kernel.org/r/20251030132007.3742368-2-andriy.shevchenko@linux.intel.com
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Feng Tang <feng.tang@linux.alibaba.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Andy Shevchenko
2025-10-30 12:44:17 +01:00
committed by Andrew Morton
parent 3e4b89e970
commit d79a3aeb74
1 changed files with 5 additions and 2 deletions
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7
lib/sys_info.c
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@@ -58,11 +58,11 @@ int sysctl_sys_info_handler(const struct ctl_table *ro_table, int write,
char names[sizeof(sys_info_avail)];
struct ctl_table table;
unsigned long *si_bits_global;
unsigned long si_bits;
si_bits_global = ro_table->data;
if (write) {
unsigned long si_bits;
int ret;
table = *ro_table;
@@ -81,9 +81,12 @@ int sysctl_sys_info_handler(const struct ctl_table *ro_table, int write,
char *delim = "";
int i, len = 0;
/* The access to the global value is not synchronized. */
si_bits = READ_ONCE(*si_bits_global);
names[0] = '\0';
for (i = 0; i < ARRAY_SIZE(si_names); i++) {
if (*si_bits_global & si_names[i].bit) {
if (si_bits & si_names[i].bit) {
len += scnprintf(names + len, sizeof(names) - len,
"%s%s", delim, si_names[i].name);
delim = ",";