[PATCH tty 0/1] Make 8250 deferred MSR handling LAZY

[John Ogness]

There was a report and follow-up discussion [0] about a problem
using regular irq_work queuing on some platforms when entering
cpuidle. To circumvent this problem, all irq_work for printk will
become IRQ_WORK_LAZY [1].

The 8250 console driver uses irq_work to defer MSR handling during
atomic printing. This means it is vulnerable to the same problem if,
for example, a WARN() is hit while entering cpuidle on one of the
affected platforms.

Avoid the problem for deferred MSR handling by changing
console_msr_work to IRQ_WORK_LAZY.

[0] https://lore.kernel.org/lkml/f3757a75-0ba1-4558-bf57-f19ab7e59a4c@xxxxxxxxxx
[1] https://lore.kernel.org/lkml/20260828140218.232439-1-john.ogness@xxxxxxxxxxxxx

John Ogness (1):
  serial: 8250: Change console_msr_work to IRQ_WORK_LAZY

 drivers/tty/serial/8250/8250_port.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)


base-commit: 45c13f3f9e3bb15fd89ff2864c6f627a3b4b4229
-- 
2.47.3