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[PATCH] Xmon bug fix for soft-reset

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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>
This commit is contained in:
Haren Myneni 2005-08-03 15:08:18 +10:00 committed by Linus Torvalds
parent 0b2bfb4e7f
commit 5cb4cc0d82
1 changed files with 3 additions and 0 deletions
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3
arch/ppc64/xmon/xmon.c
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@ -329,13 +329,16 @@ int xmon_core(struct pt_regs *regs, int fromipi)
printf("cpu 0x%x: Exception %lx %s in xmon, " printf("cpu 0x%x: Exception %lx %s in xmon, "
"returning to main loop\n", "returning to main loop\n",
cpu, regs->trap, getvecname(TRAP(regs))); cpu, regs->trap, getvecname(TRAP(regs)));
release_output_lock();
longjmp(xmon_fault_jmp[cpu], 1); longjmp(xmon_fault_jmp[cpu], 1);
} }
if (setjmp(recurse_jmp) != 0) { if (setjmp(recurse_jmp) != 0) {
if (!in_xmon || !xmon_gate) { if (!in_xmon || !xmon_gate) {
get_output_lock();
printf("xmon: WARNING: bad recursive fault " printf("xmon: WARNING: bad recursive fault "
"on cpu 0x%x\n", cpu); "on cpu 0x%x\n", cpu);
release_output_lock();
goto waiting; goto waiting;
} }
secondary = !(xmon_taken && cpu == xmon_owner); secondary = !(xmon_taken && cpu == xmon_owner);