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Fixed

LIN5-5063 : possible deadlock in panic()

Created: Apr 8, 2013    Updated: Dec 19, 2017
Resolved Date: Jul 30, 2013
Found In Version: 5.0.1
Fix Version: 5.0.1.6
Severity: Severe
Applicable for: Wind River Linux 5
Component/s: Kernel

Description

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.

For full details and the upstream patch see:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/kernel/panic.c?id=190320c3b6640d4104650f55ff69611e050ea06b

Steps to Reproduce

unknown

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