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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: Nick Piggin <npiggin@suse.de>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Nick Piggin 2008-02-06 01:37:04 -08:00 committed by Linus Torvalds
parent 5bd91f18be
commit b0940003f2
1 changed files with 5 additions and 3 deletions
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8
drivers/char/vt.c
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@ -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)