rcu: Provide cond_resched_rcu_qs() to force quiescent states in long loops
RCU-tasks requires the occasional voluntary context switch
from CPU-bound in-kernel tasks. In some cases, this requires
instrumenting cond_resched(). However, there is some reluctance
to countenance unconditionally instrumenting cond_resched() (see
http://lwn.net/Articles/603252/), so this commit creates a separate
cond_resched_rcu_qs() that may be used in place of cond_resched() in
locations prone to long-duration in-kernel looping.
This commit currently instruments only RCU-tasks. Future possibilities
include also instrumenting RCU, RCU-bh, and RCU-sched in order to reduce
IPI usage.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
diff --git a/fs/file.c b/fs/file.c
index 66923fe..1cafc4c 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -367,7 +367,7 @@
struct file * file = xchg(&fdt->fd[i], NULL);
if (file) {
filp_close(file, files);
- cond_resched();
+ cond_resched_rcu_qs();
}
}
i++;
