| Subject | Re: [PATCH v3 50/77] ncr5380: Change instance->host_lock to hostdata->lock | From | Hannes Reinecke <> | Date | Tue, 22 Dec 2015 08:46:41 +0100 |
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On 12/22/2015 02:18 AM, Finn Thain wrote: > NCR5380.c presently uses the instance->host_lock spin lock. Convert this > to a new spin lock that protects the NCR5380_hostdata struct. > > atari_NCR5380.c previously used local_irq_save/restore() rather than a > spin lock. Convert this to hostdata->lock in irq mode. For SMP platforms, > the interrupt handler now also acquires the spin lock. > > This brings all locking in the two core drivers into agreement. > > Adding this locking also means that a bunch of volatile qualifiers can be > removed from the members of the NCR5380_hostdata struct. This is done in > a subsequent patch. > > Proper locking will allow the abort handler to locate a command being > aborted. This is presently impossible if the abort handler is invoked when > the command has been moved from a queue to a pointer on the stack. (If > eh_abort_handler can't determine whether a command has been completed > or is still being processed then it can't decide whether to return > success or failure.) > > The hostdata spin lock is now held when calling NCR5380_select() and > NCR5380_information_transfer(). Where possible, the lock is dropped for > polling and PIO transfers. > > Clean up the now-redundant SELECT_ENABLE_REG writes, that used to provide > limited mutual exclusion between information_transfer() and reselect(). > > Accessing hostdata->connected without data races means taking the lock; > cleanup these accesses. > > The new spin lock falls away for m68k and other UP builds, so this should > have little impact there. In the SMP case the new lock should be > uncontested even when the SCSI bus is contested. > > Signed-off-by: Finn Thain <fthain@telegraphics.com.au> > Reviewed-by: Hannes Reinecke <hare@suse.com>
Cheers,
Hannes -- Dr. Hannes Reinecke zSeries & Storage hare@suse.de +49 911 74053 688 SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg)
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