Commit 5cb4cc0d authored Aug 03, 2005 by Haren Myneni Committed by Linus Torvalds Aug 02, 2005

[PATCH] Xmon bug fix for soft-reset



For soft reset during system hang, got an error "CPU did not take
control" for some CPUs even though they responded to soft-reset (called
SystemReset, die and called debugger - xmon).   First these CPUs entered
into xmon by IPI callback and then got a soft-reset exception and
re-entered into xmon again. The first CPU which re-entered into xmon got
the output lock and made into xmon successfully without unlocking.
Hence, the next CPU(s) which re-entered into xmon try to acquire a lock
(get_output_lock). Therefore, we can not view state of those CPU(s).

[This is a simple, very low risk, obvious fix for an obvious bug, and
should go into 2.6.13.  -- paulus]

Signed-off-by: Haren Myneni <hbabu@us.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

parent 0b2bfb4e

arch/ppc64/xmon/xmon.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -329,13 +329,16 @@ int xmon_core(struct pt_regs *regs, int fromipi)
		printf("cpu 0x%x: Exception %lx %s in xmon, "
		"returning to main loop\n",
		cpu, regs->trap, getvecname(TRAP(regs)));
		release_output_lock();
		longjmp(xmon_fault_jmp[cpu], 1);
		}

		if (setjmp(recurse_jmp) != 0) {
		if (!in_xmon \|\| !xmon_gate) {
		get_output_lock();
		printf("xmon: WARNING: bad recursive fault "
		"on cpu 0x%x\n", cpu);
		release_output_lock();
		goto waiting;
		}
		secondary = !(xmon_taken && cpu == xmon_owner);

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