fill_result_tf() grabs the taskfile flags from the originating qc which
sas_ata_qc_fill_rtf() promptly overwrites.  The presence of an
ata_taskfile in the sata_device makes it tempting to just copy the full
contents in sas_ata_qc_fill_rtf().  However, libata really only wants
the fis contents and expects the other portions of the taskfile to not
be touched by ->qc_fill_rtf.  To that end store a fis buffer in the
sata_device and use ata_tf_from_fis() like every other ->qc_fill_rtf()
implementation.

Cc: <stable@vger.kernel.org>
Reported-by: Praveen Murali <pmurali@logicube.com>
Tested-by: Praveen Murali <pmurali@logicube.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

When requeuing work to a draining workqueue the last work instance may
not be idle, so sas_queue_work() must not touch work->entry.  Introduce
sas_work with a drain_node list_head to have a private list for
collecting work deferred due to drain collision.

Fixes reports like:
  BUG: unable to handle kernel NULL pointer dereference at           (null)
  IP: [<ffffffff810410d4>] process_one_work+0x2e/0x338

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

libata issues follow up srsts when the controller has a hard time
recording the signature-fis after a reset, or if the link supports port
multipliers.  libsas does not support port multipliers and no current
libsas lldds appear to need help retrieving the signature fis.  Revert
it for now to remove confusion.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

libsas ata error handling is already async but this does not help the
scan case.  Move initial link recovery out from under host->scan_mutex,
and delay synchronization with eh until after all port probe/recovery
work has been queued.

Device ordering is maintained with scan order by still calling
sas_rphy_add() in order of domain discovery.

Since we now scan the domain list when invoking libata-eh we need to be
careful to check for fully initialized ata ports.

Acked-by: Jack Wang <jack_wang@usish.com>
Acked-by: Jeff Garzik <jgarzik@redhat.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

If the top level expander is hot removed, mark all child devices as gone
before unregistration to short circuit futile recovery.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

In the direct-attached case this routine returns the phy on which this
device was first discovered.  Which is broken if we want to support
wide-targets, as this phy reference can become stale even though the
port is still active.

In the expander-attached case this routine tries to lookup the phy by
scanning the attached sas addresses of the parent expander, and BUG_ONs
if it can't find it.  However since eh and the libsas workqueue run
independently we can still be attempting device recovery via eh after
libsas has recorded the device as detached.  This is even easier to hit
now that eh is blocked while device domain rediscovery takes place, and
that libata is fed more timed out commands increasing the chances that
it will try to recover the ata device.

Arrange for dev->phy to always point to a last known good phy, it may be
stale after the port is torn down, but it will catch up for wide port
reconfigurations, and never be NULL.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

Use ata_wait_after_reset() to poll for link recovery after a reset.
This combined with sas_ha->eh_mutex prevents expander rediscovery from
probing phys in an intermediate state.  Local discovery does not have a
mechanism to filter link status changes during this timeout, so it
remains the responsibility of lldds to prevent premature port teardown.
Although once all lldd's support ->lldd_ata_check_ready() that could be
used as a gate to local port teardown.

The signature fis is re-transmitted when the link comes back so we
should be revalidating the ata device class, but that is left to a future
patch.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

SAS does not tag SMP requests, and at least one lldd (isci) does not permit
more than one in-flight request at a time.

[jejb: fix sas_init_dev tab issues while we're at it]
Signed-off-by: Jeff Skirvin <jeffrey.d.skirvin@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

Execute the link-reset triggered by sas_phy_enable via
transport_sas_phy_reset so that it can be managed by libata.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

libsas-eh if it successfully aborts an ata command will hide the timeout
condition (AC_ERR_TIMEOUT) from libata.  The command likely completes
with the all-zero task->task_status it started with.  Instead, interpret
a TMF_RESP_FUNC_COMPLETE as the end of the sas_task but keep the scmd
around for libata-eh to handle.

Tested-by: Andrzej Jakowski <andrzej.jakowski@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>