tree 915bc0bf46796da8193fcf933897a2deb4cc99f3
parent a882d3560c5490ca260ce456ef1846f28a5896bf
author Vikram Mulukutla <markivx@codeaurora.org> 1340843146 -0700
committer Jeremie <jer_l_@live.ca> 1342373636 -0400

panic: Fix a possible deadlock in panic()

panic_lock is meant to ensure that panic processing takes
place only on one cpu; if any of the other cpus encounter
a panic, they will spin waiting to be shut down.

However, this causes a regression in this scenario:

1. Cpu 0 encounters a panic and acquires the panic_lock
   and proceeds with the panic processing.
2. There is an interrupt on cpu 0 that also encounters
   an error condition and invokes panic.
3. This second invocation fails to acquire the panic_lock
   and enters the infinite while loop in panic_smp_self_stop.

Thus all panic processing is stopped, and the cpu is stuck
for eternity in the while(1) inside panic_smp_self_stop.

To address this, disable local interrupts with
local_irq_disable before acquiring the panic_lock. This will
prevent interrupt handlers from executing during the panic
processing, thus avoiding this particular problem.

Signed-off-by: Vikram Mulukutla <markivx@codeaurora.org>
(cherry picked from commit dd58afef43357f265e803c317bbaa91f8c440663)

Change-Id: I5f7ebcf2a028df265a57922b6c959e686a82026a
Signed-off-by: Swetha Basineni <sbasin@codeaurora.org>