From 5cb4cc0d8211c490537c8568001958fc76741312 Mon Sep 17 00:00:00 2001 From: Haren Myneni Date: Wed, 3 Aug 2005 15:08:18 +1000 Subject: [PATCH] [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 Signed-off-by: Paul Mackerras Signed-off-by: Linus Torvalds --- arch/ppc64/xmon/xmon.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/ppc64/xmon/xmon.c b/arch/ppc64/xmon/xmon.c index 7f6e13a4b71e..05539439e6bc 100644 --- a/arch/ppc64/xmon/xmon.c +++ b/arch/ppc64/xmon/xmon.c @@ -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);