From 63c4db78e80407976e47bccaa2a4d8251b5a10bc Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Fri, 9 Aug 2013 12:19:29 -0700 Subject: rcu: Add tracing to rcu_gp_kthread() This commit adds tracing to the rcu_gp_kthread() function in order to help trace down hangs potentially involving this kthread. Reported-by: Clark Williams Reported-by: Carsten Emde Signed-off-by: Paul E. McKenney --- kernel/rcutree.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) (limited to 'kernel/rcutree.c') diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 6d028fdbf86c..78d371526667 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -1480,6 +1480,9 @@ static int __noreturn rcu_gp_kthread(void *arg) /* Handle grace-period start. */ for (;;) { + trace_rcu_grace_period(rsp->name, + ACCESS_ONCE(rsp->gpnum), + TPS("reqwait")); wait_event_interruptible(rsp->gp_wq, ACCESS_ONCE(rsp->gp_flags) & RCU_GP_FLAG_INIT); @@ -1487,6 +1490,9 @@ static int __noreturn rcu_gp_kthread(void *arg) break; cond_resched(); flush_signals(current); + trace_rcu_grace_period(rsp->name, + ACCESS_ONCE(rsp->gpnum), + TPS("reqwaitsig")); } /* Handle quiescent-state forcing. */ @@ -1500,6 +1506,9 @@ static int __noreturn rcu_gp_kthread(void *arg) for (;;) { if (!ret) rsp->jiffies_force_qs = jiffies + j; + trace_rcu_grace_period(rsp->name, + ACCESS_ONCE(rsp->gpnum), + TPS("fqswait")); ret = wait_event_interruptible_timeout(rsp->gp_wq, ((gf = ACCESS_ONCE(rsp->gp_flags)) & RCU_GP_FLAG_FQS) || @@ -1513,12 +1522,21 @@ static int __noreturn rcu_gp_kthread(void *arg) /* If time for quiescent-state forcing, do it. */ if (ULONG_CMP_GE(jiffies, rsp->jiffies_force_qs) || (gf & RCU_GP_FLAG_FQS)) { + trace_rcu_grace_period(rsp->name, + ACCESS_ONCE(rsp->gpnum), + TPS("fqsstart")); fqs_state = rcu_gp_fqs(rsp, fqs_state); + trace_rcu_grace_period(rsp->name, + ACCESS_ONCE(rsp->gpnum), + TPS("fqsend")); cond_resched(); } else { /* Deal with stray signal. */ cond_resched(); flush_signals(current); + trace_rcu_grace_period(rsp->name, + ACCESS_ONCE(rsp->gpnum), + TPS("fqswaitsig")); } j = jiffies_till_next_fqs; if (j > HZ) { -- cgit v1.2.3