Commit 243d5ab3 authored by Zhen Lei's avatar Zhen Lei Committed by Frederic Weisbecker
Browse files

rcu: Eliminate check_cpu_stall() duplicate code 



The code and comments of self-detected and other-detected RCU CPU stall
warnings are identical except the output function.  This commit therefore
refactors so as to consolidate the duplicate code.

Signed-off-by: default avatarZhen Lei <thunder.leizhen@huawei.com>
Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
Signed-off-by: default avatarFrederic Weisbecker <frederic@kernel.org>
parent f3efe02f

kernel/rcu/tree_stall.h

+15 −27
Original line number Diff line number Diff line
@@ -711,7 +711,7 @@ static void print_cpu_stall(unsigned long gps) 


static void check_cpu_stall(struct rcu_data *rdp)

{

	bool didstall = false;

	bool self_detected;

	unsigned long gs1;

	unsigned long gs2;

	unsigned long gps;
@@ -758,10 +758,10 @@ static void check_cpu_stall(struct rcu_data *rdp) 
		return; /* No stall or GP completed since entering function. */

	rnp = rdp->mynode;

	jn = jiffies + ULONG_MAX / 2;

	self_detected = READ_ONCE(rnp->qsmask) & rdp->grpmask;

	if (rcu_gp_in_progress() &&

	    (READ_ONCE(rnp->qsmask) & rdp->grpmask) &&

	    (self_detected || ULONG_CMP_GE(j, js + RCU_STALL_RAT_DELAY)) &&

	    cmpxchg(&rcu_state.jiffies_stall, js, jn) == js) {



		/*

		 * If a virtual machine is stopped by the host it can look to

		 * the watchdog like an RCU stall. Check to see if the host
@@ -770,35 +770,23 @@ static void check_cpu_stall(struct rcu_data *rdp) 
		if (kvm_check_and_clear_guest_paused())

			return;



		if (self_detected) {

			/* We haven't checked in, so go dump stack. */

			print_cpu_stall(gps);

		if (READ_ONCE(rcu_cpu_stall_ftrace_dump))

			rcu_ftrace_dump(DUMP_ALL);

		didstall = true;



	} else if (rcu_gp_in_progress() &&

		   ULONG_CMP_GE(j, js + RCU_STALL_RAT_DELAY) &&

		   cmpxchg(&rcu_state.jiffies_stall, js, jn) == js) {



		/*

		 * If a virtual machine is stopped by the host it can look to

		 * the watchdog like an RCU stall. Check to see if the host

		 * stopped the vm.

		 */

		if (kvm_check_and_clear_guest_paused())

			return;



		} else {

			/* They had a few time units to dump stack, so complain. */

			print_other_cpu_stall(gs2, gps);

		}



		if (READ_ONCE(rcu_cpu_stall_ftrace_dump))

			rcu_ftrace_dump(DUMP_ALL);

		didstall = true;

	}

	if (didstall && READ_ONCE(rcu_state.jiffies_stall) == jn) {



		if (READ_ONCE(rcu_state.jiffies_stall) == jn) {

			jn = jiffies + 3 * rcu_jiffies_till_stall_check() + 3;

			WRITE_ONCE(rcu_state.jiffies_stall, jn);

		}

	}

}



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