Spurious interrupts are often encountered especially on systems
using the 8259 PIC mode. This is because the I/O write to deassert
the interrupt is posted and won't get to the chip immediately. As
a result, the IRQ may remain asserted after the IRQ handler exits,
causing spurious interrupts.
Flush the interrupt mailbox in non-MSI handlers to de-assert the
IRQ immediately. This seems to be the most straight forward approach
after discussion with Jeff Garzik and David Miller.
Signed-off-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
c04cb34725