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05 April 2024, 19:05:47 UTC
Revision 6029755eed95e5c90f763188c87ae3ff41e48e5c authored by Nicholas Piggin on 27 April 2018, 01:51:59 UTC, committed by Michael Ellerman on 27 April 2018, 06:35:57 UTC 
powerpc: Fix deadlock with multiple calls to smp_send_stop
 
smp_send_stop can lock up the IPI path for any subsequent calls,
because the receiving CPUs spin in their handler function. This
started becoming a problem with the addition of an smp_send_stop
call in the reboot path, because panics can reboot after doing
their own smp_send_stop.

The NMI IPI variant was fixed with ac61c11566 ("powerpc: Fix
smp_send_stop NMI IPI handling"), which leaves the smp_call_function
variant.

This is fixed by having smp_send_stop only ever do the
smp_call_function once. This is a bit less robust than the NMI IPI
fix, because any other call to smp_call_function after smp_send_stop
could deadlock, but that has always been the case, and it was not
been a problem before.

Fixes: f2748bdfe1573 ("powerpc/powernv: Always stop secondaries before reboot/shutdown")
Reported-by: Abdul Haleem <abdhalee@linux.vnet.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
1 parent c0f7f5b
History
Tip revision: 6029755eed95e5c90f763188c87ae3ff41e48e5c authored by Nicholas Piggin on 27 April 2018, 01:51:59 UTC
powerpc: Fix deadlock with multiple calls to smp_send_stop
Tip revision: 6029755
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