powerpc/irq: Don't switch to irq stack from softirq stack
authorBenjamin Herrenschmidt <benh@kernel.crashing.org>
Mon, 7 Oct 2013 21:08:24 +0000 (08:08 +1100)
committerLinus Torvalds <torvalds@linux-foundation.org>
Mon, 7 Oct 2013 21:19:39 +0000 (14:19 -0700)
commit8b5ede69d24db939f52b47effff2f6fe1e83e08b
treec492c191c688296cdd708e1d9e5fc6cc63197edf
parentfd848319e751739a93aa9fc8182e57e87c5a0df1
powerpc/irq: Don't switch to irq stack from softirq stack

irq_exit() is now called on the irq stack, which can trigger a switch to
the softirq stack from the irq stack.  If an interrupt happens at that
point, we will not properly detect the re-entrancy and clobber the
original return context on the irq stack.

This fixes it.  The side effect is to prevent all nesting from softirq
stack to irq stack even in the "safe" case but it's simpler that way and
matches what x86_64 does.

Reported-by: Cédric Le Goater <clg@fr.ibm.com>
Tested-by: Cédric Le Goater <clg@fr.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
arch/powerpc/kernel/irq.c