From: Vikram Mulukutla Date: Mon, 30 Jul 2012 21:39:58 +0000 (-0700) Subject: panic: fix a possible deadlock in panic() X-Git-Tag: v3.6-rc1~41^2~103 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=190320c3b6640d4104650f55ff69611e050ea06b;p=pandora-kernel.git 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 Reviewed-by: Stephen Boyd Cc: Michael Holzheu Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Reading git-diff-tree failed