On 8/6/26 4:39 AM, John Garry wrote: > Getting the address of embedded host_lock structure just requires adding > a fixed offset value to the shost pointer. However, getting the value of > the host_lock pointer requires loading from a fixed offset to the shost > pointer. The latter should be very slightly slower, which is relevant as > this lock is used a lot throughout the core code and drivers. Hmm ... SCSI drivers for which performance matters shouldn't use the SCSI host lock in their hot path.
Any driver which uses DEF_SCSI_QCMD uses this lock in the fastpath. However I don't think that many are high performance HBAs. Maybe usb/storage/ or pmcraid could be consider higher performing.
Then there is stuff like xen-scsifront.c which uses this lock in the cmd done handler. It's used a lot in lpfc and also in code which looks to be fastpath...but that drivers is very complex.
> @Bart, Can you kindly build test this? s390 and sh were causing some build > issues for me. Thanks This patch passes my build tests, but an update for the references to default_lock in the Documentation/ directory is missing.
I'll fix it
Otherwise this patch looks good to me. So with or without the Documentation/ update, feel free to add: Reviewed-by: Bart Van Assche <[email protected]>
thanks
