genirq: Run irq handlers with interrupts disabled

genirq: Run irq handlers with interrupts disabled

Running interrupt handlers with interrupts enabled can cause stack
overflows. That has been observed with multiqueue NICs delivering all
their interrupts to a single core. We might band aid that somehow by
checking the interrupt stacks, but the real safe fix is to run the irq
handlers with interrupts disabled.

Drivers for whacky hardware still can reenable them in the handler
itself, if the need arises. (They do already due to lockdep)

The risk of doing this is rather low:

 - lockdep already enforces this
 - CONFIG_NOHZ has shaken out the drivers which relied on jiffies updates
 - time keeping is not longer sensitive to the timer interrupt being delayed

Signed-off-by: Ingo Molnar <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Alan Cox <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: David Miller <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Linus Torvalds <[email protected]>
LKML-Reference: <20100326000405.758579387@linutronix.de>