[Kernel-janitors] [PATCH] fix SMP support in cdu535 cdrom driver

        Hi Jens,

        Patch against 2.6.0-test6.

	Even though cdu535 is polled, not interrupt driven, Matthew pointed 
out[1] that is a good idea to fix SMP support on that bit, so that 
people who wants to fix cdu31a don't get that wrong.

	Move prepare_to_wait before enable_interrupts, so that if we enter 
the interrupt handler (after enable_interrupts) on a different CPU 
that's executing sony_sleep's poll version, "wait" is already on the 
irq_wait list, which I think fixes the race that Matthew pointed out, 
doesn't it?

	CC'ing kernel-janitors since it also replaces yield for 
schedule_timeout[2], as Matthew suggested.

        Please consider applying.

        Thanks,

Felipe

[1] http://marc.theaimsgroup.com/?l=linux-kernel&m=106322465303649&w=2

[2] 
http://lists.osdl.org/pipermail/kernel-janitors/2003-October/000173.html
--- linux-2.6.0-test6/drivers/cdrom/sonycd535.c.orig    2003-10-08 
14:42:43.000000000 -0300
+++ linux-2.6.0-test6/drivers/cdrom/sonycd535.c 2003-10-08 16:00:09.000000000 
-0300
@@ -342,13 +342,14 @@
 sony_sleep(void)
 {
        if (sony535_irq_used <= 0) {    /* poll */
-               yield();
+               set_current_state(TASK_INTERRUPTIBLE);
+               schedule_timeout(1);
        } else {        /* Interrupt driven */
                DEFINE_WAIT(wait);
-               
+
                spin_lock_irq(&sonycd535_lock);
-               enable_interrupts();
                prepare_to_wait(&cdu535_irq_wait, &wait, TASK_INTERRUPTIBLE);
+               enable_interrupts();
                spin_unlock_irq(&sonycd535_lock);
                schedule();
                finish_wait(&cdu535_irq_wait, &wait);
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