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ipmi: fix potential deadlock on &kcs_bmc->lock

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As kcs_bmc_handle_event() is executed inside both a timer and a hardirq,
it should disable irq before lock acquisition otherwise deadlock could
happen if the timmer is preemtped by the irq.

Possible deadlock scenario:
aspeed_kcs_check_obe() (timer)
    -> kcs_bmc_handle_event()
    -> spin_lock(&kcs_bmc->lock)
        <irq interruption>
        -> aspeed_kcs_irq()
        -> kcs_bmc_handle_event()
        -> spin_lock(&kcs_bmc->lock) (deadlock here)

This flaw was found using an experimental static analysis tool we are
developing for irq-related deadlock.

The tentative patch fix the potential deadlock by spin_lock_irqsave()

Signed-off-by: Chengfeng Ye <dg573847474@gmail.com>
Message-Id: <20230627152449.36093-1-dg573847474@gmail.com>
Signed-off-by: Corey Minyard <minyard@acm.org>
This commit is contained in:
Chengfeng Ye 2023-06-27 15:24:49 +00:00 committed by Corey Minyard
parent 6cf1a126de
commit b02bb79eee
1 changed files with 3 additions and 2 deletions
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5
drivers/char/ipmi/kcs_bmc.c
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@ -56,12 +56,13 @@ irqreturn_t kcs_bmc_handle_event(struct kcs_bmc_device *kcs_bmc)
{
struct kcs_bmc_client *client;
irqreturn_t rc = IRQ_NONE;
unsigned long flags;
spin_lock(&kcs_bmc->lock);
spin_lock_irqsave(&kcs_bmc->lock, flags);
client = kcs_bmc->client;
if (client)
rc = client->ops->event(client);
spin_unlock(&kcs_bmc->lock);
spin_unlock_irqrestore(&kcs_bmc->lock, flags);
return rc;
}