On 05/22/2017 02:48 PM, hch@xxxxxx wrote: > On Mon, May 22, 2017 at 10:46:10AM +0200, Hannes Reinecke wrote: >>> That seems to be overkill to me for the few drivers. And I suspect >>> most of them would be better off now even using blk-mq private tags >>> (which we'd have to implement for the legacy path first or just >>> kill it off) but just not expose a tag per host to the scsi and block >>> layers and set that aside. >>> >> IE not using blk-mq private tags for EH? Hmm. >> But then we'd need a SCSI-internal mechanism to get one of them. I >> really would want to avoid having each driver to implement it's own >> mechanism on how to get a TMF tag; that sort of thing only leads to >> copy-and-paste errors. >> Ok; will be looking into it. > > No, we don't. The driver simply sets a tag aside and doesn't expose > it to the block layer. Similar to what smartpqi already does for LUN > resets and AENs, mpt3sas does for the ioctl tags and NVMe does for AERs. > Personally I feel a bit uncomfortable by setting aside just one tag for TMFs; this assumes we'll never be sending LUN resets to devices in parallel. But maybe this is a discussion for another time, if and when we finally move to that. Cheers, Hannes -- Dr. Hannes Reinecke zSeries & Storage hare@xxxxxxxx +49 911 74053 688 SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: F. Imendörffer, J. Smithard, D. Upmanyu, G. Norton HRB 21284 (AG Nürnberg)
