Is test_and_set_bit() _BUS_ atomic? [cli/sti in char/vt.c [patch]]

Andrea Arcangeli (arcangeli@mbox.queen.it)
Sun, 31 May 1998 19:51:02 +0200 (CEST)

On Sat, 30 May 1998, Pavel Machek wrote:

>Because in i386 port it _IS_ atomic, so in arch/i386 you can assume
>that test_and_set_bit is atomic. Strange, is not it? Should be
>documented somewhere.

I don' t bother of arch/i386! The topic is about common code!!!!!!!!!!

OK, I' ll try again (and better):

Can I use test_and_set_bit() to avoid a SMP race in
drivers/char/lp.c and so to make lp_open() SMP safe? (I don' t need it
atomic in respect of interrupts but I need it atomic in respect of the
RAM memory BUS)

Thanks.

Andrea[s] Arcangeli

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