[PATCH] libata-eh-fw: implement new EH scheduling via error completion
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>
diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index 1c34c14..1f5c32709 100644
--- a/drivers/scsi/libata-core.c
+++ b/drivers/scsi/libata-core.c
@@ -4123,6 +4123,66 @@
qc->complete_fn(qc);
}
+/**
+ * ata_qc_complete - Complete an active ATA command
+ * @qc: Command to complete
+ * @err_mask: ATA Status register contents
+ *
+ * Indicate to the mid and upper layers that an ATA
+ * command has completed, with either an ok or not-ok status.
+ *
+ * LOCKING:
+ * spin_lock_irqsave(host_set lock)
+ */
+void ata_qc_complete(struct ata_queued_cmd *qc)
+{
+ struct ata_port *ap = qc->ap;
+
+ /* XXX: New EH and old EH use different mechanisms to
+ * synchronize EH with regular execution path.
+ *
+ * In new EH, a failed qc is marked with ATA_QCFLAG_FAILED.
+ * Normal execution path is responsible for not accessing a
+ * failed qc. libata core enforces the rule by returning NULL
+ * from ata_qc_from_tag() for failed qcs.
+ *
+ * Old EH depends on ata_qc_complete() nullifying completion
+ * requests if ATA_QCFLAG_EH_SCHEDULED is set. Old EH does
+ * not synchronize with interrupt handler. Only PIO task is
+ * taken care of.
+ */
+ if (ap->ops->error_handler) {
+ WARN_ON(ap->flags & ATA_FLAG_FROZEN);
+
+ if (unlikely(qc->err_mask))
+ qc->flags |= ATA_QCFLAG_FAILED;
+
+ if (unlikely(qc->flags & ATA_QCFLAG_FAILED)) {
+ if (!ata_tag_internal(qc->tag)) {
+ /* always fill result TF for failed qc */
+ ap->ops->tf_read(ap, &qc->result_tf);
+ ata_qc_schedule_eh(qc);
+ return;
+ }
+ }
+
+ /* read result TF if requested */
+ if (qc->flags & ATA_QCFLAG_RESULT_TF)
+ ap->ops->tf_read(ap, &qc->result_tf);
+
+ __ata_qc_complete(qc);
+ } else {
+ if (qc->flags & ATA_QCFLAG_EH_SCHEDULED)
+ return;
+
+ /* read result TF if failed or requested */
+ if (qc->err_mask || qc->flags & ATA_QCFLAG_RESULT_TF)
+ ap->ops->tf_read(ap, &qc->result_tf);
+
+ __ata_qc_complete(qc);
+ }
+}
+
static inline int ata_should_dma_map(struct ata_queued_cmd *qc)
{
struct ata_port *ap = qc->ap;
@@ -5245,7 +5305,7 @@
EXPORT_SYMBOL_GPL(ata_host_set_remove);
EXPORT_SYMBOL_GPL(ata_sg_init);
EXPORT_SYMBOL_GPL(ata_sg_init_one);
-EXPORT_SYMBOL_GPL(__ata_qc_complete);
+EXPORT_SYMBOL_GPL(ata_qc_complete);
EXPORT_SYMBOL_GPL(ata_qc_issue_prot);
EXPORT_SYMBOL_GPL(ata_tf_load);
EXPORT_SYMBOL_GPL(ata_tf_read);
diff --git a/drivers/scsi/libata-eh.c b/drivers/scsi/libata-eh.c
index 959a1cd..471846f 100644
--- a/drivers/scsi/libata-eh.c
+++ b/drivers/scsi/libata-eh.c
@@ -210,6 +210,33 @@
DPRINTK("EXIT\n");
}
+/**
+ * ata_qc_schedule_eh - schedule qc for error handling
+ * @qc: command to schedule error handling for
+ *
+ * Schedule error handling for @qc. EH will kick in as soon as
+ * other commands are drained.
+ *
+ * LOCKING:
+ * spin_lock_irqsave(host_set lock)
+ */
+void ata_qc_schedule_eh(struct ata_queued_cmd *qc)
+{
+ struct ata_port *ap = qc->ap;
+
+ WARN_ON(!ap->ops->error_handler);
+
+ qc->flags |= ATA_QCFLAG_FAILED;
+ qc->ap->flags |= ATA_FLAG_EH_PENDING;
+
+ /* The following will fail if timeout has already expired.
+ * ata_scsi_error() takes care of such scmds on EH entry.
+ * Note that ATA_QCFLAG_FAILED is unconditionally set after
+ * this function completes.
+ */
+ scsi_req_abort_cmd(qc->scsicmd);
+}
+
static void ata_eh_scsidone(struct scsi_cmnd *scmd)
{
/* nada */
diff --git a/drivers/scsi/libata.h b/drivers/scsi/libata.h
index c9ff83b..52622b7 100644
--- a/drivers/scsi/libata.h
+++ b/drivers/scsi/libata.h
@@ -57,6 +57,7 @@
unsigned int *classes);
extern void ata_qc_free(struct ata_queued_cmd *qc);
extern void ata_qc_issue(struct ata_queued_cmd *qc);
+extern void __ata_qc_complete(struct ata_queued_cmd *qc);
extern int ata_check_atapi_dma(struct ata_queued_cmd *qc);
extern void ata_dev_select(struct ata_port *ap, unsigned int device,
unsigned int wait, unsigned int can_sleep);
@@ -101,5 +102,6 @@
/* libata-eh.c */
extern enum scsi_eh_timer_return ata_scsi_timed_out(struct scsi_cmnd *cmd);
extern void ata_scsi_error(struct Scsi_Host *host);
+extern void ata_qc_schedule_eh(struct ata_queued_cmd *qc);
#endif /* __LIBATA_H__ */