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Commit 19fa6e60 authored by Denis Kirjanov's avatar Denis Kirjanov Committed by Greg Kroah-Hartman
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tty/hvc_console: fix console lock ordering with spinlock 



hvc_remove() takes a spin lock first then acquires the console
semaphore. This situation can easily lead to a deadlock scenario
where we call scheduler with spin lock held.

Signed-off-by: default avatarDenis Kirjanov <kda@linux-powerpc.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 93857edd

drivers/tty/hvc/hvc_console.c

+2 −2
Original line number Diff line number Diff line
@@ -920,17 +920,17 @@ int hvc_remove(struct hvc_struct *hp) 


	tty = tty_port_tty_get(&hp->port);



	console_lock();

	spin_lock_irqsave(&hp->lock, flags);

	if (hp->index < MAX_NR_HVC_CONSOLES) {

		console_lock();

		vtermnos[hp->index] = -1;

		cons_ops[hp->index] = NULL;

		console_unlock();

	}



	/* Don't whack hp->irq because tty_hangup() will need to free the irq. */



	spin_unlock_irqrestore(&hp->lock, flags);

	console_unlock();



	/*

	 * We 'put' the instance that was grabbed when the kref instance