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| author | Paul E. McKenney <paulmck@kernel.org> | 2022-12-14 11:41:44 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-03-10 09:29:07 +0100 |
| commit | 639bdc733fc40d263cca30a262193ed893e9e5c3 (patch) | |
| tree | b6f3f34c5cd031d1d1ba934212abb3267c56dfc6 /include | |
| parent | ba166e0ebdde3dfa833f0a3edaf2b2934d4a87f7 (diff) | |
| download | linux-639bdc733fc40d263cca30a262193ed893e9e5c3.tar.gz linux-639bdc733fc40d263cca30a262193ed893e9e5c3.tar.bz2 linux-639bdc733fc40d263cca30a262193ed893e9e5c3.zip | |
rcu: Make RCU_LOCKDEP_WARN() avoid early lockdep checks
[ Upstream commit 0cae5ded535c3a80aed94f119bbd4ee3ae284a65 ]
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 <rostedt@goodmis.org>
Reported-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reported-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'include')
| -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 c0c79beac3fe..8d4bf695e766 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -376,11 +376,18 @@ 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); \ } \ |