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| author | Gui-Dong Han <hanguidong02@gmail.com> | 2025-12-02 20:55:36 +0300 |
|---|---|---|
| committer | Guenter Roeck <linux@roeck-us.net> | 2026-01-31 18:38:30 +0300 |
| commit | d0a0960602f780362ea974c80650d87bcf13726a (patch) | |
| tree | e7119aa2ee3bfcf434516a1a9ce71a6b29cec061 | |
| parent | 615901b57b7ef8eb655f71358f7e956e42bcd16b (diff) | |
| download | linux-d0a0960602f780362ea974c80650d87bcf13726a.tar.xz | |
hwmon: submitting-patches: Explain race conditions caused by calculations in macros
The current documentation advises against calculations in macros
primarily to avoid code obfuscation. It misses the risk of concurrency
issues.
Add a note explaining that macros evaluating arguments multiple times
can lead to race conditions when accessing shared data.
Link: https://lore.kernel.org/all/CALbr=LYJ_ehtp53HXEVkSpYoub+XYSTU8Rg=o1xxMJ8=5z8B-g@mail.gmail.com/
Signed-off-by: Gui-Dong Han <hanguidong02@gmail.com>
Link: https://lore.kernel.org/r/20251202175536.12774-1-hanguidong02@gmail.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
| -rw-r--r-- | Documentation/hwmon/submitting-patches.rst | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/Documentation/hwmon/submitting-patches.rst b/Documentation/hwmon/submitting-patches.rst index 6482c4f137dc..7f7095951750 100644 --- a/Documentation/hwmon/submitting-patches.rst +++ b/Documentation/hwmon/submitting-patches.rst @@ -82,7 +82,10 @@ increase the chances of your change being accepted. * Avoid calculations in macros and macro-generated functions. While such macros may save a line or so in the source, it obfuscates the code and makes code review more difficult. It may also result in code which is more complicated - than necessary. Use inline functions or just regular functions instead. + than necessary. Such macros may also evaluate their arguments multiple times. + This leads to Time-of-Check to Time-of-Use (TOCTOU) race conditions when + accessing shared data without locking, for example when calculating values in + sysfs show functions. Use inline functions or just regular functions instead. * Limit the number of kernel log messages. In general, your driver should not generate an error message just because a runtime operation failed. Report |