Implement new EH. The exported interface is ata_do_eh() which is to
be called from ->error_handler and performs the following steps to
recover the failed port.
ata_eh_autopsy() : analyze SError/TF, determine the cause of failure
and required recovery actions and record it in
ap->eh_context
ata_eh_report() : report the failure to user
ata_eh_recover() : perform recovery actions described in ap->eh_context
ata_eh_finish() : finish failed qcs
LLDDs can customize error handling by modifying eh_context before
calling ata_do_eh() or, if necessary, doing so inbetween each major
steps by calling each step explicitly.
Signed-off-by: Tejun Heo <htejun@gmail.com>
struct ata_eh_info serves as the communication channel between
execution path and EH. Execution path describes detected error
condition in ap->eh_info and EH recovers the port using it. To avoid
missing error conditions detected during EH, EH makes its own copy of
eh_info and clears it on entry allowing error info to accumulate
during EH.
Most EH states including EH's copy of eh_info are stored in
ap->eh_context (struct ata_eh_context) which is owned by EH and thus
doesn't require any synchronization to access and alter. This
standardized context makes it easy to integrate various parts of EH
and extend EH to handle multiple links (for PM).
Signed-off-by: Tejun Heo <htejun@gmail.com>
This patch implements ata_ering and uses it to define dev->ering.
ata_ering is a ring buffer which records libata errors - whether a
command was for normar IO request, err_mask and timestamp. Errors are
recorded per-device in dev->ering. This will be used by EH to
determine recovery actions.
Signed-off-by: Tejun Heo <htejun@gmail.com>
Update ata_scsi_error() for new EH. ata_scsi_error() is responsible
for claiming timed out qcs and invoking ->error_handler in safe and
synchronized manner. As the state of the controller is unknown if a
qc has timed out, the port is frozen in such cases.
Note that ata_scsi_timed_out() isn't used for new EH. This is because
a timed out qc cannot be claimed by EH without freezing the port and
freezing the port in ata_scsi_timed_out() results in unnecessary
abortion of other active qcs. ata_scsi_timed_out() can be removed
once all drivers are converted to new EH.
While at it, add 'TODO: kill' comments to old EH functions.
Signed-off-by: Tejun Heo <htejun@gmail.com>
Freezing is performed atomic w.r.t. host_set->lock and once frozen
LLDD is not allowed to access the port or any qc on it. Also, libata
makes sure that no new qc gets issued to a frozen port.
A frozen port is thawed after a reset operation completes
successfully, so reset methods must do its job while the port is
frozen. During initialization all ports get frozen before requesting
IRQ, so reset methods are always invoked on a frozen port.
Optional ->freeze and ->thaw operations notify LLDD that the port is
being frozen and thawed, respectively. LLDD can disable/enable
hardware interrupt in these callbacks if the controller's IRQ mask can
be changed dynamically. If the controller doesn't allow such
operation, LLDD can check for frozen state in the interrupt handler
and ack/clear interrupts unconditionally while frozen.
Signed-off-by: Tejun Heo <htejun@gmail.com>
ata_port_schedule_eh() directly schedules EH for @ap without
associated qc. Once EH scheduled, no further qc is allowed and EH
kicks in as soon as all currently active qc's are drained.
ata_port_abort() schedules all currently active commands for EH by
qc_completing them with ATA_QCFLAG_FAILED set. If ata_port_abort()
doesn't find any qc to abort, it directly schedule EH using
ata_port_schedule_eh().
These two functions provide ways to invoke EH for conditions which
aren't directly related to any specfic qc.
Signed-off-by: Tejun Heo <htejun@gmail.com>
There are several ways a qc can get schedule for EH in new EH. This
patch implements one of them - completing a qc with ATA_QCFLAG_FAILED
set or with non-zero qc->err_mask. ALL such qc's are examined by EH.
New EH schedules a qc for EH from completion iff ->error_handler is
implemented, qc is marked as failed or qc->err_mask is non-zero and
the command is not an internal command (internal cmd is handled via
->post_internal_cmd). The EH scheduling itself is performed by asking
SCSI midlayer to schedule EH for the specified scmd.
For drivers implementing old-EH, nothing changes. As this change
makes ata_qc_complete() rather large, it's not inlined anymore and
__ata_qc_complete() is exported to other parts of libata for later
use.
Signed-off-by: Tejun Heo <htejun@gmail.com>
A lot of EH codes are about to be added to libata. Separate out
libata-eh.c. ata_scsi_timed_out(), ata_scsi_error(),
ata_qc_timeout(), ata_eng_timeout(), ata_eh_qc_complete() and
ata_eh_qc_retry() are moved. No code is changed by this patch.
Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
