Andre Noll said: (by the date of Thu, 6 Mar 2008 11:51:34 +0100) > But is that enough to avoid the deadlock? I think the following > scenario would be possible with the code in the original patch: > > // suppose conf->pending_bio_list.head==NULL ATM > > CPU0: > int rv = 0; > spin_lock_irq(&conf->device_lock); > if (conf->pending_bio_list.head) // false > spin_unlock_irq(&conf->device_lock); > > CPU1: > conf->pending_bio_list.head = something; > > CPU0: > return rv; // zero Remember that it's impossible to predict when is executed what. This scenario can be true also, will it work? CPU0: int rv = 0; CPU1: conf-> CPU0: spin_lock_irq(&conf->device_lock); CPU1: ->pending_bio_list. CPU0: if (conf->pending_bio_list.head) // false CPU1: .head = CPU0: spin_unlock_irq(&conf->device_lock); return rv; // zero CPU1: = something; This is exaggerated of course. But if you want to think "concurrent execution" you must think that way. -- Janek Kozicki | -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
