3.16.57-rc1 review patch. If anyone has any objections, please let me know.
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From: Nicholas Piggin npiggin@gmail.com
commit acb1feab320e38588fccc568e3767761f494976f upstream.
When an interrupt is returning to a soft-disabled context (which can happen for non-maskable interrupts or synchronous interrupts), it goes through the motions of soft-disabling again, including calling TRACE_DISABLE_INTS (i.e., trace_hardirqs_off()).
This is not necessary, because we must already be soft-disabled in the interrupt context, it also may be causing crashes in the irq tracing code to re-enter as an nmi. Replace it with a warning to ensure that soft-interrupts are still disabled.
Fixes: 7c0482e3d055 ("powerpc/irq: Fix another case of lazy IRQ state getting out of sync") Signed-off-by: Nicholas Piggin npiggin@gmail.com Signed-off-by: Michael Ellerman mpe@ellerman.id.au [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- arch/powerpc/kernel/entry_64.S | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-)
--- a/arch/powerpc/kernel/entry_64.S +++ b/arch/powerpc/kernel/entry_64.S @@ -885,9 +885,13 @@ restore_irq_off: beq 1f rlwinm r7,r7,0,~PACA_IRQ_HARD_DIS stb r7,PACAIRQHAPPENED(r13) -1: li r0,0 - stb r0,PACASOFTIRQEN(r13); - TRACE_DISABLE_INTS +1: +#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_BUG) + /* The interrupt should not have soft enabled. */ + lbz r7,PACASOFTIRQEN(r13) +1: tdnei r7,0 + EMIT_BUG_ENTRY 1b,__FILE__,__LINE__,BUGFLAG_WARNING +#endif b do_restore
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