On Sat, 15 Mar 2003, bert hubert wrote:
> A construct like this was suggested for use in swsusp too to make sure that
> only *one* request is outstanding for a controler. This was also mentioned
> to be the unclean way and that there are taskfile interfaces which are
> cleaner.
hmm..
cpu0:
do_IRQ();
handle_IRQ_event();
...
static ide_startstop_t read_intr (ide_drive_t *drive)
{
msect = drive->mult_count; /* let msect = 0 */
...
if (i > 0) {
if (msect)
goto read_next;
if (HWGROUP(drive)->handler != NULL) <- [1]
BUG();
ide_set_handler(drive, &read_intr, WAIT_CMD, NULL); <- [2]
return ide_started;
}
}
cpu1:
swsusp code;
...
spin_lock_irqsave(&ide_lock, flags);
while (HWGROUP(drive)->handler) {
HWGROUP(drive)->handler = NULL; <- [1]
schedule_timeout(1);
}
<- [2]
...
Ok so at event [1] we have a ->handler set on cpu0 so we pass that check.
Then cpu1 acquires ide_lock and NULLs it out. cpu0 blocks on the lock in
ide_set_handler and when cpu1 releases it it re-assigns ->handler. What
happens then?
Zwane
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This archive was generated by hypermail 2b29 : Sat Mar 15 2003 - 22:00:43 EST