torture: Dump ftrace buffer when the RCU grace period stalls

This commit adds a call to rcutorture_trace_dump() to dump the ftrace
buffer when the RCU grace period stalls in order to help debug the
stall.  Note that this is different than the RCU CPU stall warning,
as it is rcutorture detecting the stall rather than the underlying RCU
implementation.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>

diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 80d2d2440210b3cf92ac4df6c6681074878d7040..9decce0f110ca7810bf23d01871df8647c39fc5a 100644 (file)
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -1034,6 +1034,7 @@ rcu_torture_printk(char *page)
                                "??? Writer stall state %d g%lu c%lu f%#x\n",
                                rcu_torture_writer_state,
                                gpnum, completed, flags);
+               rcutorture_trace_dump();
        }
        rtcv_snap = rcu_torture_current_version;
 }