diff options
| author | Paul E. McKenney <paulmck@kernel.org> | 2026-07-12 10:50:08 -0700 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2026-07-23 10:48:12 -0700 |
| commit | 647dd6e09481daa23d93e927c2b7f46a3acf8a03 (patch) | |
| tree | 58e7ad97a1a9a3ae19ab8c2e4591f7a85fdc6bf7 /include/linux | |
| parent | ef21090071b33844f55fac7c5470729b862dad0c (diff) | |
rcu-tasks: Apply READ_ONCE() and WRITE_ONCE() to fix data race
Now that rcutorture tests readers from interrupt handlers, KCSAN spotted
an additional data race. This commit therefore fixes it by applying
READ_ONCE() and WRITE_ONCE().
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/rcupdate_trace.h | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/include/linux/rcupdate_trace.h b/include/linux/rcupdate_trace.h index cee89e51e45c..fd3ddeb6aa3b 100644 --- a/include/linux/rcupdate_trace.h +++ b/include/linux/rcupdate_trace.h @@ -95,10 +95,13 @@ static inline void rcu_read_unlock_tasks_trace(struct srcu_ctr __percpu *scp) */ static inline void rcu_read_lock_trace(void) { + int n; struct task_struct *t = current; rcu_try_lock_acquire(&rcu_tasks_trace_srcu_struct.dep_map); - if (t->trc_reader_nesting++) { + n = READ_ONCE(t->trc_reader_nesting); + WRITE_ONCE(t->trc_reader_nesting, n + 1); + if (n) { // In case we interrupted a Tasks Trace RCU reader. return; } @@ -119,12 +122,15 @@ static inline void rcu_read_lock_trace(void) */ static inline void rcu_read_unlock_trace(void) { + int n; struct srcu_ctr __percpu *scp; struct task_struct *t = current; scp = t->trc_reader_scp; barrier(); // scp before nesting to protect against interrupt handler. - if (!--t->trc_reader_nesting) { + n = READ_ONCE(t->trc_reader_nesting) - 1; + WRITE_ONCE(t->trc_reader_nesting, n); + if (!n) { if (!IS_ENABLED(CONFIG_TASKS_TRACE_RCU_NO_MB)) smp_mb(); // Placeholder for more selective ordering __srcu_read_unlock_fast(&rcu_tasks_trace_srcu_struct, scp); |