diff options
| author | Vikram Mulukutla <markivx@codeaurora.org> | 2012-07-30 14:39:58 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-04-12 09:38:47 -0700 |
| commit | 5592a94b44df6e6d48e34cfe596844637a2976ac (patch) | |
| tree | 75de4b4f29df40c505eefb9627a4149c5a66b125 | |
| parent | ddcd89f15f9e85d5cd37c866a1c5da9a3ca204d1 (diff) | |
panic: fix a possible deadlock in panic()
commit 190320c3b6640d4104650f55ff69611e050ea06b upstream.
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>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Cc: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | kernel/panic.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/kernel/panic.c b/kernel/panic.c index 9ed023b8333a..10b7685997c3 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -75,6 +75,14 @@ void panic(const char *fmt, ...) int state = 0; /* + * Disable local interrupts. This will prevent panic_smp_self_stop + * from deadlocking the first cpu that invokes the panic, since + * there is nothing to prevent an interrupt handler (that runs + * after the panic_lock is acquired) from invoking panic again. + */ + local_irq_disable(); + + /* * It's possible to come here directly from a panic-assertion and * not have preempt disabled. Some functions called from here want * preempt to be disabled. No point enabling it later though... |