powerpc: NMI IPI improve lock primitive
authorNicholas Piggin <npiggin@gmail.com>
Wed, 9 Aug 2017 12:41:21 +0000 (22:41 +1000)
committerMichael Ellerman <mpe@ellerman.id.au>
Wed, 9 Aug 2017 13:45:26 +0000 (23:45 +1000)
commit0459ddfdb31e7d812b555a2530ecbacdf96961a6
tree872d7e7c3ea27de89c18a2710c672038281f2c8e
parent7310d5c8c55e8987a854507f71022f8de676bbf4
powerpc: NMI IPI improve lock primitive

When the NMI IPI lock is contended, spin at low SMT priority, using
loads only, and with interrupts enabled (where possible). This
improves behaviour under high contention (e.g., a system crash when
a number of CPUs are trying to enter the debugger).

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
arch/powerpc/kernel/smp.c