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powerpc: System reset avoid interleaving oops using die synchronisation 

The die() oops path contains a serializing lock to prevent oops
messages from being interleaved. In the case of a system reset
initiated oops (e.g., qemu nmi command), __die was being called
which lacks that synchronisation and oops reports could be
interleaved across CPUs.

A recent patch 4388c9b3a6 ("powerpc: Do not send system reset
request through the oops path") changed this to __die to avoid
the debugger() call, but there is no real harm to calling it twice
if the first time fell through. So go back to using die() here.
This was observed to fix the problem.

Fixes: 4388c9b3a6 ("powerpc: Do not send system reset request through the oops path")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Nicholas Piggin 2017-12-24 02:49:22 +10:00 committed by Michael Ellerman
parent 2271db20e4
commit 4552d128c2
1 changed files with 1 additions and 1 deletions
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2
arch/powerpc/kernel/traps.c
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@ -337,7 +337,7 @@ void system_reset_exception(struct pt_regs *regs)
* No debugger or crash dump registered, print logs then * No debugger or crash dump registered, print logs then
* panic. * panic.
*/ */
__die("System Reset", regs, SIGABRT); die("System Reset", regs, SIGABRT);
mdelay(2*MSEC_PER_SEC); /* Wait a little while for others to print */ mdelay(2*MSEC_PER_SEC); /* Wait a little while for others to print */
add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE); add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);