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x86/i8259: Use printk_deferred() to prevent deadlock

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0day reported a possible circular locking dependency:

Chain exists of:
  &irq_desc_lock_class --> console_owner --> &port_lock_key

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&port_lock_key);
                               lock(console_owner);
                               lock(&port_lock_key);
  lock(&irq_desc_lock_class);

The reason for this is a printk() in the i8259 interrupt chip driver
which is invoked with the irq descriptor lock held, which reverses the
lock operations vs. printk() from arbitrary contexts.

Switch the printk() to printk_deferred() to avoid that.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/87365abt2v.fsf@nanos.tec.linutronix.de
This commit is contained in:
Thomas Gleixner 2020-07-29 10:53:28 +02:00 committed by Ingo Molnar
parent 92ed301919
commit bdd6558959
1 changed files with 1 additions and 1 deletions
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2
arch/x86/kernel/i8259.c
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@ -207,7 +207,7 @@ spurious_8259A_irq:
* lets ACK and report it. [once per IRQ]
*/
if (!(spurious_irq_mask & irqmask)) {
printk(KERN_DEBUG
printk_deferred(KERN_DEBUG
"spurious 8259A interrupt: IRQ%d.\n", irq);
spurious_irq_mask |= irqmask;
}