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Commit b0940003 authored by Nick Piggin's avatar Nick Piggin Committed by Linus Torvalds
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vt: bitlock fix 



vt is missing a memory barrier to close the critical section.  Use a real
spinlock for this.

Signed-off-by: default avatarNick Piggin <npiggin@suse.de>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 5bd91f18

drivers/char/vt.c

+5 −3
Original line number Diff line number Diff line
@@ -2400,13 +2400,15 @@ static void vt_console_print(struct console *co, const char *b, unsigned count) 
{

	struct vc_data *vc = vc_cons[fg_console].d;

	unsigned char c;

	static unsigned long printing;

	static DEFINE_SPINLOCK(printing_lock);

	const ushort *start;

	ushort cnt = 0;

	ushort myx;



	/* console busy or not yet initialized */

	if (!printable || test_and_set_bit(0, &printing))

	if (!printable)

		return;

	if (!spin_trylock(&printing_lock))

		return;



	if (kmsg_redirect && vc_cons_allocated(kmsg_redirect - 1))
@@ -2481,7 +2483,7 @@ static void vt_console_print(struct console *co, const char *b, unsigned count) 
	notify_update(vc);



quit:

	clear_bit(0, &printing);

	spin_unlock(&printing_lock);

}



static struct tty_driver *vt_console_device(struct console *c, int *index)