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Commit 064996d6 authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Michael Ellerman
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powerpc/xmon: Avoid tripping SMP hardlockup watchdog 



The SMP hardlockup watchdog cross-checks other CPUs for lockups, which
causes xmon headaches because it's assuming interrupts hard disabled
means no watchdog troubles. Try to improve that by calling
touch_nmi_watchdog() in obvious places where secondaries are spinning.

Also annotate these spin loops with spin_begin/end calls.

Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent 80e4d70b

arch/powerpc/xmon/xmon.c

+13 −4
Original line number Diff line number Diff line
@@ -530,14 +530,19 @@ static int xmon_core(struct pt_regs *regs, int fromipi) 


 waiting:

	secondary = 1;

	spin_begin();

	while (secondary && !xmon_gate) {

		if (in_xmon == 0) {

			if (fromipi)

			if (fromipi) {

				spin_end();

				goto leave;

			}

			secondary = test_and_set_bit(0, &in_xmon);

		}

		barrier();

		spin_cpu_relax();

		touch_nmi_watchdog();

	}

	spin_end();



	if (!secondary && !xmon_gate) {

		/* we are the first cpu to come in */
@@ -568,21 +573,25 @@ static int xmon_core(struct pt_regs *regs, int fromipi) 
		mb();

		xmon_gate = 1;

		barrier();

		touch_nmi_watchdog();

	}



 cmdloop:

	while (in_xmon) {

		if (secondary) {

			spin_begin();

			if (cpu == xmon_owner) {

				if (!test_and_set_bit(0, &xmon_taken)) {

					secondary = 0;

					spin_end();

					continue;

				}

				/* missed it */

				while (cpu == xmon_owner)

					barrier();

					spin_cpu_relax();

			}

			barrier();

			spin_cpu_relax();

			touch_nmi_watchdog();

		} else {

			cmd = cmds(regs);

			if (cmd != 0) {