8250.c: port.lock is irq-safe
serial8250_startup() doesn't disable interrupts while taking the &up->port.lock
which might race against the interrupt handler serial8250_interrupt(), which
when entered, will deadlock waiting for the lock to be released.
Signed-off-by: Borislav Petkov <petkovbb@gmail.com>
Tested-by: Ingo Molnar <mingo@elte.hu>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c
index a97f1ae..342e12f 100644
--- a/drivers/serial/8250.c
+++ b/drivers/serial/8250.c
@@ -1885,7 +1885,7 @@
* the interrupt is enabled. Delays are necessary to
* allow register changes to become visible.
*/
- spin_lock(&up->port.lock);
+ spin_lock_irqsave(&up->port.lock, flags);
if (up->port.flags & UPF_SHARE_IRQ)
disable_irq_nosync(up->port.irq);
@@ -1901,7 +1901,7 @@
if (up->port.flags & UPF_SHARE_IRQ)
enable_irq(up->port.irq);
- spin_unlock(&up->port.lock);
+ spin_unlock_irqrestore(&up->port.lock, flags);
/*
* If the interrupt is not reasserted, setup a timer to