*/
void cleanup_srcu_struct(struct srcu_struct *sp)
{
- int sum;
-
- sum = srcu_readers_active(sp);
- WARN_ON(sum); /* Leakage unless caller handles error. */
- if (sum != 0)
- return;
+ if (WARN_ON(srcu_readers_active(sp)))
+ return; /* Leakage unless caller handles error. */
free_percpu(sp->per_cpu_ref);
sp->per_cpu_ref = NULL;
}
*/
void __srcu_read_unlock(struct srcu_struct *sp, int idx)
{
- preempt_disable();
smp_mb(); /* C */ /* Avoid leaking the critical section. */
- ACCESS_ONCE(this_cpu_ptr(sp->per_cpu_ref)->c[idx]) -= 1;
- preempt_enable();
+ this_cpu_dec(sp->per_cpu_ref->c[idx]);
}
EXPORT_SYMBOL_GPL(__srcu_read_unlock);
!lock_is_held(&rcu_sched_lock_map),
"Illegal synchronize_srcu() in same-type SRCU (or RCU) read-side critical section");
+ might_sleep();
init_completion(&rcu.completion);
head->next = NULL;
* synchronize_srcu - wait for prior SRCU read-side critical-section completion
* @sp: srcu_struct with which to synchronize.
*
- * Flip the completed counter, and wait for the old count to drain to zero.
- * As with classic RCU, the updater must use some separate means of
- * synchronizing concurrent updates. Can block; must be called from
- * process context.
+ * Wait for the count to drain to zero of both indexes. To avoid the
+ * possible starvation of synchronize_srcu(), it waits for the count of
+ * the index=((->completed & 1) ^ 1) to drain to zero at first,
+ * and then flip the completed and wait for the count of the other index.
+ *
+ * Can block; must be called from process context.
*
* Note that it is illegal to call synchronize_srcu() from the corresponding
* SRCU read-side critical section; doing so will result in deadlock.