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-rw-r--r--include/linux/rcupdate.h5
1 files changed, 4 insertions, 1 deletions
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 981f9aa43353..b87aefa082e2 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -240,11 +240,14 @@ extern int rcu_pending(int cpu);
* This means that all preempt_disable code sequences, including NMI and
* hardware-interrupt handlers, in progress on entry will have completed
* before this primitive returns. However, this does not guarantee that
- * softirq handlers will have completed, since in some kernels
+ * softirq handlers will have completed, since in some kernels, these
+ * handlers can run in process context, and can block.
*
* This primitive provides the guarantees made by the (deprecated)
* synchronize_kernel() API. In contrast, synchronize_rcu() only
* guarantees that rcu_read_lock() sections will have completed.
+ * In "classic RCU", these two guarantees happen to be one and
+ * the same, but can differ in realtime RCU implementations.
*/
#define synchronize_sched() synchronize_rcu()