Commit 75437bb3 authored Jan 10, 2017 by Pan Xinhui Committed by Ingo Molnar Jan 12, 2017

locking/pvqspinlock: Don't wait if vCPU is preempted

If prev node is not in running state or its vCPU is preempted, we can give
up our vCPU slices in pv_wait_node() ASAP.

Signed-off-by: Pan Xinhui <xinhui.pan@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: longman@redhat.com
Link: http://lkml.kernel.org/r/1484035006-6787-1-git-send-email-xinhui.pan@linux.vnet.ibm.com

[ Fixed typos in the changelog, removed ugly linebreak from the code. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent 607904c3

kernel/locking/qspinlock_paravirt.h

+1 −1

Original line number	Original line	Diff line number	Diff line
	@@ -263,7 +263,7 @@ pv_wait_early(struct pv_node *prev, int loop)
	if ((loop & PV_PREV_CHECK_MASK) != 0)		if ((loop & PV_PREV_CHECK_MASK) != 0)
	return false;		return false;

	return READ_ONCE(prev->state) != vcpu_running;		return READ_ONCE(prev->state) != vcpu_running \|\| vcpu_is_preempted(prev->cpu);
	}		}

	/*		/*