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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>
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@ -1885,7 +1885,7 @@ static int serial8250_startup(struct uart_port *port)
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* the interrupt is enabled. Delays are necessary to
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* allow register changes to become visible.
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*/
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spin_lock(&up->port.lock);
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spin_lock_irqsave(&up->port.lock, flags);
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if (up->port.flags & UPF_SHARE_IRQ)
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disable_irq_nosync(up->port.irq);
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@ -1901,7 +1901,7 @@ static int serial8250_startup(struct uart_port *port)
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if (up->port.flags & UPF_SHARE_IRQ)
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enable_irq(up->port.irq);
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spin_unlock(&up->port.lock);
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spin_unlock_irqrestore(&up->port.lock, flags);
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/*
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* If the interrupt is not reasserted, setup a timer to
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