Merge branch 'rcu/next' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-2.6-rcu into core/rcu

1 files changed, 7 insertions, 1 deletions

diff --git a/kernel/srcu.c b/kernel/srcu.c
index c71e07500536..98d8c1e80edb 100644
--- a/kernel/srcu.c
+++ b/kernel/srcu.c
@@ -31,6 +31,7 @@
 #include <linux/rcupdate.h>
 #include <linux/sched.h>
 #include <linux/smp.h>
+#include <linux/delay.h>
 #include <linux/srcu.h>
 
 static int init_srcu_struct_fields(struct srcu_struct *sp)
@@ -203,9 +204,14 @@ static void __synchronize_srcu(struct srcu_struct *sp, void (*sync_func)(void))
          * all srcu_read_lock() calls using the old counters have completed.
          * Their corresponding critical sections might well be still
          * executing, but the srcu_read_lock() primitives themselves
-         * will have finished executing.
+         * will have finished executing.  We initially give readers
+         * an arbitrarily chosen 10 microseconds to get out of their
+         * SRCU read-side critical sections, then loop waiting 1/HZ
+         * seconds per iteration.
          */
 
+        if (srcu_readers_active_idx(sp, idx))
+                udelay(CONFIG_SRCU_SYNCHRONIZE_DELAY);
         while (srcu_readers_active_idx(sp, idx))
                 schedule_timeout_interruptible(1);