On 7/4/19 3:19 PM, Paolo Bonzini wrote: > On 19/06/19 12:31, Paolo Bonzini wrote: >>> I'm a bit unsure if 'bd->last' is always set; it's quite obvious that >>> it's present if set, but what about requests with 'bd->last == false' ? >>> Is there a guarantee that they will _always_ be followed with a request >>> with bd->last == true? >>> And if so, is there a guarantee that this request is part of the same batch? >> It's complicated. A request with bd->last == false _will_ always be >> followed by a request with bd->last == true in the same batch. However, >> due to e.g. errors it may be possible that the last request is not sent. >> In that case, the block layer sends commit_rqs, as documented in the >> comment above, to flush the requests that have been sent already. >> >> So, a driver that obeys bd->last (or SCMD_LAST) but does not implement >> commit_rqs is bound to have bugs, which is why this patch was not split >> further. >> >> Makes sense? > > Hannes, can you provide your Reviewed-by? > Well ... since you asked for it: Where is the 'commit_rqs' callback actually used? I seem to be going blind, but I can't find it; should be somewhere in the first patch, no? As per description: * The commit_rqs function is used to trigger a hardware * doorbell after some requests have been queued with * queuecommand, when an error is encountered before sending * the request with SCMD_LAST set. So it should be somewhere in the error path, probably scsi_error or something. But I don't seem to be able to find it ... Cheers, Hannes -- Dr. Hannes Reinecke Teamlead Storage & Networking hare@xxxxxxx +49 911 74053 688 SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: Felix Imendörffer, Mary Higgins, Sri Rasiah HRB 21284 (AG Nürnberg)
