not present" don't print any message but still return ENODEV.
Use this in cd driver to allow open of character raw partition even if
the drive is empty (older drives fails at LOAD_UNLOAD time, newer
ones fail at TEST_UNIT_READY time).
some devices can't handle tag number larger than some values and always
reject commands with QUEUE FULL if the tag number is larger than this.
Under some circonstances the scsipi system may not decrease periph_openings
(as a workaround of other odd behavior) and we may end up requeuing the command
with a hight tag value again, and the driver could loop on this.
Workaround: in case of queue full, decrease periph_openings to
min(periph_active - 1, periph_openings - 1) so that, after some iteration,
periph_openings is less than the max tag value acceptable by the device.
Solves the problem with tagged queuing on ncr53c9x for me.
This is a completely rewritten scsipi_xfer execution engine, and the
associated changes to HBA drivers. Overview of changes & features:
- All xfers are queued in the mid-layer, rather than doing so in an
ad-hoc fashion in individual adapter drivers.
- Adapter/channel resource management in the mid-layer, avoids even trying
to start running an xfer if the adapter/channel doesn't have the resources.
- Better communication between the mid-layer and the adapters.
- Asynchronous event notification mechanism from adapter to mid-layer and
peripherals.
- Better peripheral queue management: freeze/thaw, sorted requeueing during
recovery, etc.
- Clean separation of peripherals, adapters, and adapter channels (no more
scsipi_link).
- Kernel thread for each scsipi_channel makes error recovery much easier
(no more dealing with interrupt context when recovering from an error).
- Mid-layer support for tagged queueing: commands can have the tag type
set explicitly, tag IDs are allocated in the mid-layer (thus eliminating
the need to use buggy tag ID allocation schemes in many adapter drivers).
- support for QUEUE FULL and CHECK CONDITION status in mid-layer; the command
will be requeued, or a REQUEST SENSE will be sent as appropriate.
Just before the merge syssrc has been tagged with thorpej_scsipi_beforemerge
to remove all xfers from the pending queue. It removes only xfers for
asynchronous transactions. So, simply loop over all pending xfers
with calling scsipi_done and wait xfers to drain. Addresses PR#9703.
timeout()/untimeout() API:
- Clients supply callout handle storage, thus eliminating problems of
resource allocation.
- Insertion and removal of callouts is constant time, important as
this facility is used quite a lot in the kernel.
The old timeout()/untimeout() API has been removed from the kernel.
- `flags' is now gone, replaced with `xs_control' and `xs_status'.
- Massive cleanup of the control flags. Now we explicitly say that
a job is to complete asynchronously, rather than relying on side-effects,
and use a new flag to now that device discovery is being performed.
- Do SCSI device discovery interrupt-driven.
in the drive. restrict "opening of empty drive" to character devices only
(reading a block device returns a short read instead of ENODEV, which can lead
to confusion).
pending_xfers queue.
- When freeing a scsipi_xfer, remove it from the device's pending_xfers
queue. If the queue is empty, and SDEV_WAITDRAIN is set, wakeup
those waiting for the queue to drain.
- Implement scsipi_wait_drain(), which waits for a device's pending_xfers
queue to drain.
scsi_base.c to scsipi_base.c. Rename the functions from scsi_verbose.c
too, and rename the file itself. Cleaup includes too (scsi_*.h should not
be #included in scsipi_*.h files, which are supposed to be
common to atapi and scsi).
in scsipi_done() if the transfer is asynchronous. This reduces the size
of the critical section in scsipi_execute_xs() somewhat (in fact,
back to its original size).
(probably due to an interrupt) between the time it is scheduled and the
time we get around to setting the SCSI_ASYNCREQ flag, we can lose the xs.
Fix this by checking to see if the transfer has already completed after
the scsi_cmd function returns SUCCESSFULLY_QUEUED, and just return to the
caller if so.
scsipi_xfer structures.
When scsipi_execute_xs() calls the driver's scsi_cmd function, it assumes
that it can still dereference a pointer to the scsipi_xfer struct. Since
scsipi_done() has already been called, which in turn has called
scsipi_free_xs(), the struct has already been returned to the pool! In
other words, xs->flags has been compromised, but we are still testing it.
These changes resolve the problem by doing the following:
- In scsipi_execute_xs(), if the lower-level driver's scsi_cmd function
returns SUCCESSFULLY_QUEUED and SCSI_NOSLEEP is set in xs->flags, set a
new flag (SCSI_ASYNCREQ). This indicates that scsipi_done() should free
the scsipi_xfer struct.
If the lower-level driver's scsi_cmd function returns SUCCESSFULLY_QUEUED
but SCSI_NOSLEEP is not set, we wait (via tsleep()) for the request to
complete, then fall through to the COMPLETE case.
If the lower-level driver's scsi_cmd function returns COMPLETE, we now
simply return any actual errors, or 0 if none occurred. (Previously,
we may have returned EJUSTRETURN, of which the sole effect was to
avoid freeing the scsipi_xfer struct in our caller. No code seems
to depend on this behavior, however.)
- In scsipi_done(), only free the scsipi_xfer struct for async requests.
The contents of the struct will otherwise remain valid until the
function that initiated the transfer frees it.
With this change, responsibility for freeing the struct now lies in two
places, depending on the type of the request:
- For synchronous requests, the routine calling scsipi_execute_xs()
must clean up.
- For asynchronous requests, scsipi_done() cleans up (as it always has).
[Note: this change also corrects a problem with sddump(): scsipi_done()
was attempting to return a static scsipi_xfer struct to the pool! Since
dumps are performed synchronously, we now handle this correctly.]
This solution was provided by Jason Thorpe, after I got him to look at
some related (but insufficient) attempts of my own.
mjacob