This is a compromise and a temporary workaround for bootup NMI
watchdog triggers some people see with qla2xxx devices present.
This happens when, for example:
CPU 0 is in the driver init and looping submitting mailbox commands to
load the firmware, then waiting for completion.
CPU 1 is receiving the device interrupts. CPU 1 is where the NMI
watchdog triggers.
CPU 0 is submitting mailbox commands fast enough that by the time CPU
1 returns from the device interrupt handler, a new one is pending.
This sequence runs for more than 5 seconds.
The problematic case is CPU 1's timer interrupt running when the
barrage of device interrupts begin. Then we have:
timer interrupt
return for softirq checking
pending, thus enable interrupts
qla2xxx interrupt
return
qla2xxx interrupt
return
... 5+ seconds pass
final qla2xxx interrupt for fw load
return
run timer softirq
return
At some point in the multi-second qla2xxx interrupt storm we trigger
the NMI watchdog on CPU 1 from the NMI interrupt handler.
The timer softirq, once we get back to running it, is smart enough to
run the timer work enough times to make up for the missed timer
interrupts.
However, the NMI watchdogs (both x86 and sparc) use the timer
interrupt count to notice the cpu is wedged. But in the above
scenerio we'll receive only one such timer interrupt even if we last
all the way back to running the timer softirq.
The default watchdog trigger point is only 5 seconds, which is pretty
low (the softwatchdog triggers at 60 seconds). So increase it to 30
seconds for now.
Signed-off-by: David S. Miller <davem@davemloft.net>
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