8250.c: port.lock is irq-safe (c389d27b) · Commits · 戴 / test

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>

drivers/serial/8250.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -1885,7 +1885,7 @@ static int serial8250_startup(struct uart_port *port)
		* 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 @@ static int serial8250_startup(struct uart_port *port)

		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

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