From: Haren Myneni <[EMAIL PROTECTED]> 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 <[EMAIL PROTECTED]> Signed-off-by: Paul Mackerras <[EMAIL PROTECTED]> --- --- linux-2.6.13-rc4-git4/arch/ppc64/xmon/xmon.c.orig 2005-08-01 22:31:09.000000000 -0700 +++ linux-2.6.13-rc4-git4/arch/ppc64/xmon/xmon.c 2005-08-01 22:33:16.000000000 -0700 @@ -329,13 +329,16 @@ int xmon_core(struct pt_regs *regs, int 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); - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/