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author | Thomas Gleixner <tglx@linutronix.de> | 2020-07-29 11:53:28 +0300 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-08-05 11:06:53 +0300 |
commit | ba6e4d6a92c9d02153861e5693665d4a89caf5d0 (patch) | |
tree | 79989a77344aa2c2a57004d74dab79fda2c06f77 | |
parent | ba53d9deccbac6e0670bd9b1849663ecda54d648 (diff) | |
download | linux-ba6e4d6a92c9d02153861e5693665d4a89caf5d0.tar.xz |
x86/i8259: Use printk_deferred() to prevent deadlock
commit bdd65589593edd79b6a12ce86b3b7a7c6dae5208 upstream.
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
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r-- | arch/x86/kernel/i8259.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/kernel/i8259.c b/arch/x86/kernel/i8259.c index 02abc134367f..f7833ae4e3f1 100644 --- a/arch/x86/kernel/i8259.c +++ b/arch/x86/kernel/i8259.c @@ -206,7 +206,7 @@ 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; } |