This commit adds a trace event which allows tracing the beginnings of RCU
CPU stall warnings on systems where sysctl_panic_on_rcu_stall is disabled.
The first parameter is the name of RCU flavor like other trace events.
The second parameter indicates whether this is a stall of an expedited
grace period, a self-detected stall of a normal grace period, or a stall
of a normal grace period detected by some CPU other than the one that
is stalled.
RCU CPU stall warnings are often caused by external-to-RCU issues,
for example, in interrupt handling or task scheduling. Therefore,
this event uses TRACE_EVENT, not TRACE_EVENT_RCU, to avoid requiring
those interested in tracing RCU CPU stalls to rebuild their kernels
with CONFIG_RCU_TRACE=y.
Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Reviewed-by: Neeraj Upadhyay <neeraju@codeaurora.org>
Signed-off-by: Sangmoon Kim <sangmoon.kim@samsung.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
(cherry picked from commit 71580d6503f747f1b06ef8dbb7cdbbe20400a2ec
git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git dev)
Bug: 177483057
Change-Id: Ie2f0340725a2fb582d026ecfaf5e1d35cc90fece
Signed-off-by: Sangmoon Kim <sangmoon.kim@samsung.com>
f23fe39801