On Wed, 2010-11-10 at 18:52 -0500, Jeff Garzik wrote: > On 11/10/2010 06:45 PM, James Bottomley wrote: > > On Wed, 2010-11-10 at 18:28 -0500, Jeff Garzik wrote: > >> On 11/10/2010 05:40 PM, James Bottomley wrote: > >>> Your commit: > >>> > >>> [SCSI] host lock push-down > >>> > >>> Move the mid-layer's ->queuecommand() invocation from being locked > >>> with the host lock to being unlocked to facilitate speeding up the > >>> critical path for drivers who don't need this lock taken anyway. > >>> > >>> The patch below presents a simple SCSI host lock push-down as an > >>> equivalent transformation. No locking or other behavior should change > >>> with this patch. All existing bugs and locking orders are preserved. > >>> > >>> Minimal code disturbance was attempted with this change. Most drivers > >>> needed only two one-line modifications for their host lock push-down. > >>> > >>> Signed-off-by: Jeff Garzik<jgarzik@xxxxxxxxxx> > >>> Signed-off-by: James Bottomley<James.Bottomley@xxxxxxx> > >>> > >>> has been added to the upstream SCSI tree > >>> You can find it here: > >> > >> No comments on renaming ->queuecommand to something else? > > > > What we wondered about doing differently isn't really relevant for a > > change log ... that should just really be about what was done (to avoid > > confusion). > > Wasn't referring to the changelog (perhaps shouldn't have quoted that); > just asking the question generally. > > > >> The consequences are rather dire if this goes unnoticed, yes? > > > > You mean if there's a missed in-tree driver? Yes, but I took care to > > make sure all SCSI drivers were accounted for. For out of tree drivers, > > as with the eh lock push down, it's caveat emptor. > > Thinking about out-of-tree drivers, yes. > Hi Jeff and James, Thank you for getting this initial patch merged. I really think this was and is the best choice moving forward. Also, a seriously big thank you to all of the other folks who have helped identify LLDs issues for host_lock less mode for drivers!! In the next days I will get a atomic_t scsi_host->cmd_serial_number patch rebased (which is really very minor at this point w/o the scsi_error.c changes), and merge the current host_lock-less 'scoreboard' on top of jgarzik's code and tag for .38. So, please let me know if you would to include minor the atomic_t scsi_host->cmd_serial_number patch for .37 or if you would rather have this immediately preceed the first series of "enable host-lock_less for LLD vendor superturbo hba" for the .38 round. Best, --nab -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
