doc: Update removal of RCU-bh/sched update machinery
The RCU-bh update API is now defined in terms of that of RCU-bh and
RCU-sched, so this commit updates the documentation accordingly.
In addition, although RCU-sched persists in !PREEMPT kernels, in
the PREEMPT case its update API is now defined in terms of that of
RCU-preempt, so this commit also updates the documentation accordingly.
While in the area, this commit removes the documentation for the
now-obsolete synchronize_rcu_mult() and clarifies the Tasks RCU
documentation.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
diff --git a/Documentation/RCU/stallwarn.txt b/Documentation/RCU/stallwarn.txt
index f99cf11..491043f 100644
--- a/Documentation/RCU/stallwarn.txt
+++ b/Documentation/RCU/stallwarn.txt
@@ -16,12 +16,9 @@
o A CPU looping with interrupts disabled.
-o A CPU looping with preemption disabled. This condition can
- result in RCU-sched stalls and, if ksoftirqd is in use, RCU-bh
- stalls.
+o A CPU looping with preemption disabled.
-o A CPU looping with bottom halves disabled. This condition can
- result in RCU-sched and RCU-bh stalls.
+o A CPU looping with bottom halves disabled.
o For !CONFIG_PREEMPT kernels, a CPU looping anywhere in the kernel
without invoking schedule(). If the looping in the kernel is
@@ -87,9 +84,9 @@
This resulted in a series of RCU CPU stall warnings, eventually
leading the realization that the CPU had failed.
-The RCU, RCU-sched, RCU-bh, and RCU-tasks implementations have CPU stall
-warning. Note that SRCU does -not- have CPU stall warnings. Please note
-that RCU only detects CPU stalls when there is a grace period in progress.
+The RCU, RCU-sched, and RCU-tasks implementations have CPU stall warning.
+Note that SRCU does -not- have CPU stall warnings. Please note that
+RCU only detects CPU stalls when there is a grace period in progress.
No grace period, no CPU stall warnings.
To diagnose the cause of the stall, inspect the stack traces.