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| author | Vineet Gupta <vgupta@synopsys.com> | 2016-02-23 11:55:16 +0530 |
|---|---|---|
| committer | Vineet Gupta <vgupta@synopsys.com> | 2016-02-24 11:07:28 +0530 |
| commit | bb143f814ea488769ca2e79e0b376139cb5f134b (patch) | |
| tree | 32857f21fd6b8a9a4ae8457142c34260628c535e /arch/arc/kernel/entry-arcv2.S | |
| parent | 3e5177c1919bdc7651b5056f35409d0b4d728841 (diff) | |
| download | linux-bb143f814ea488769ca2e79e0b376139cb5f134b.tar.bz2 | |
ARCv2: SMP: Emulate IPI to self using software triggered interrupt
ARConnect/MCIP Inter-Core-Interrupt module can't send interrupt to
local core. So use core intc capability to trigger software
interrupt to self, using an unsued IRQ #21.
This showed up as csd deadlock with LTP trace_sched on a dual core
system. This test acts as scheduler fuzzer, triggering all sorts of
schedulting activity. Trouble starts with IPI to self, which doesn't get
delivered (effectively lost due to H/w capability), but the msg intended
to be sent remain enqueued in per-cpu @ipi_data.
All subsequent IPIs to this core from other cores get elided due to the
IPI coalescing optimization in ipi_send_msg_one() where a pending msg
implies an IPI already sent and assumes other core is yet to ack it.
After the elided IPI, other core simply goes into csd_lock_wait()
but never comes out as this core never sees the interrupt.
Fixes STAR 9001008624
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: <stable@vger.kernel.org> [4.2]
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Diffstat (limited to 'arch/arc/kernel/entry-arcv2.S')
| -rw-r--r-- | arch/arc/kernel/entry-arcv2.S | 11 |
1 files changed, 6 insertions, 5 deletions
diff --git a/arch/arc/kernel/entry-arcv2.S b/arch/arc/kernel/entry-arcv2.S index b17830294706..c1264607bbff 100644 --- a/arch/arc/kernel/entry-arcv2.S +++ b/arch/arc/kernel/entry-arcv2.S @@ -45,11 +45,12 @@ VECTOR reserved ; Reserved slots VECTOR handle_interrupt ; (16) Timer0 VECTOR handle_interrupt ; unused (Timer1) VECTOR handle_interrupt ; unused (WDT) -VECTOR handle_interrupt ; (19) ICI (inter core interrupt) -VECTOR handle_interrupt -VECTOR handle_interrupt -VECTOR handle_interrupt -VECTOR handle_interrupt ; (23) End of fixed IRQs +VECTOR handle_interrupt ; (19) Inter core Interrupt (IPI) +VECTOR handle_interrupt ; (20) perf Interrupt +VECTOR handle_interrupt ; (21) Software Triggered Intr (Self IPI) +VECTOR handle_interrupt ; unused +VECTOR handle_interrupt ; (23) unused +# End of fixed IRQs .rept CONFIG_ARC_NUMBER_OF_INTERRUPTS - 8 VECTOR handle_interrupt |