diff options
| author | Paul E. McKenney <[email protected]> | 2022-12-14 11:41:44 -0800 |
|---|---|---|
| committer | Paul E. McKenney <[email protected]> | 2023-01-03 17:28:34 -0800 |
| commit | 0cae5ded535c3a80aed94f119bbd4ee3ae284a65 (patch) | |
| tree | e0a33635c321e56bdfa7bcdefd23d7bcf9fb86fe | |
| parent | 95ff24ee7b809ff8d253cd5edf196f137ae08c44 (diff) | |
rcu: Make RCU_LOCKDEP_WARN() avoid early lockdep checks
Currently, RCU_LOCKDEP_WARN() checks the condition before checking
to see if lockdep is still enabled. This is necessary to avoid the
false-positive splats fixed by commit 3066820034b5dd ("rcu: Reject
RCU_LOCKDEP_WARN() false positives"). However, the current state can
result in false-positive splats during early boot before lockdep is fully
initialized. This commit therefore checks debug_lockdep_rcu_enabled()
both before and after checking the condition, thus avoiding both sets
of false-positive error reports.
Reported-by: Steven Rostedt <[email protected]>
Reported-by: Masami Hiramatsu (Google) <[email protected]>
Reported-by: Mathieu Desnoyers <[email protected]>
Signed-off-by: Paul E. McKenney <[email protected]>
Reviewed-by: Mathieu Desnoyers <[email protected]>
Cc: Boqun Feng <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Thomas Gleixner <[email protected]>
| -rw-r--r-- | include/linux/rcupdate.h | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 03abf883a281..aa86de01aab6 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -374,11 +374,18 @@ static inline int debug_lockdep_rcu_enabled(void) * RCU_LOCKDEP_WARN - emit lockdep splat if specified condition is met * @c: condition to check * @s: informative message + * + * This checks debug_lockdep_rcu_enabled() before checking (c) to + * prevent early boot splats due to lockdep not yet being initialized, + * and rechecks it after checking (c) to prevent false-positive splats + * due to races with lockdep being disabled. See commit 3066820034b5dd + * ("rcu: Reject RCU_LOCKDEP_WARN() false positives") for more detail. */ #define RCU_LOCKDEP_WARN(c, s) \ do { \ static bool __section(".data.unlikely") __warned; \ - if ((c) && debug_lockdep_rcu_enabled() && !__warned) { \ + if (debug_lockdep_rcu_enabled() && (c) && \ + debug_lockdep_rcu_enabled() && !__warned) { \ __warned = true; \ lockdep_rcu_suspicious(__FILE__, __LINE__, s); \ } \ |