There are several ways a qc can get schedule for EH in new EH. This
patch implements one of them - completing qc with non-zero
qc->err_mask. ALL normal qc's with set err_mask are to be examined by
EH. There's no sideway.
New EH schedules a qc for EH from completion iff ->error_handler is
implemented, 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.
Note that in the new EH, there is no way a qc can hit
ata_qc_complete() twice or normal path completes a qc which has been
scheduled for EH by other entities. The ownership is clear and must
be followed. Violation will trigger WARN_ON().
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@xxxxxxxxx>
---
drivers/scsi/libata-core.c | 52 +++++++++++++++++++++++++++++++++++++++++++-
drivers/scsi/libata-eh.c | 29 +++++++++++++++++++++++++
drivers/scsi/libata.h | 2 ++
include/linux/libata.h | 21 +-----------------
4 files changed, 83 insertions(+), 21 deletions(-)
62f9790537d3ea763d911e48f23e66bf21d7e445
diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index f019d5d..2a5d3f6 100644
--- a/drivers/scsi/libata-core.c
+++ b/drivers/scsi/libata-core.c
@@ -4192,6 +4192,56 @@ void __ata_qc_complete(struct ata_queued
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.
+ *
+ * When a qc fails, it's marked with EH_SCHEDULED. In new EH,
+ * regular 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 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(qc->flags & ATA_QCFLAG_EH_SCHEDULED ||
+ ap->flags & ATA_FLAG_FROZEN);
+
+ if (unlikely(qc->err_mask)) {
+ /* ATA_QCFLAG_FAILED is set for all failed
+ * qc's including internal qc.
+ */
+ qc->flags |= ATA_QCFLAG_FAILED;
+ if (!ata_tag_internal(qc->tag)) {
+ ata_eh_schedule_qc(qc);
+ return;
+ }
+ }
+ __ata_qc_complete(qc);
+ } else {
+ if (qc->flags & ATA_QCFLAG_EH_SCHEDULED)
+ return;
+ __ata_qc_complete(qc);
+ }
+}
+
static inline int ata_should_dma_map(struct ata_queued_cmd *qc)
{
struct ata_port *ap = qc->ap;
@@ -5177,7 +5227,7 @@ EXPORT_SYMBOL_GPL(ata_device_add);
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 e73f561..a1fe14f 100644
--- a/drivers/scsi/libata-eh.c
+++ b/drivers/scsi/libata-eh.c
@@ -210,6 +210,35 @@ void ata_eng_timeout(struct ata_port *ap
DPRINTK("EXIT\n");
}
+/**
+ * ata_eh_schedule_qc - schedule qc for error handling
+ * @qc: command to schedule error handling for
+ *
+ * Schedule error handling for the specified qc. EH will kick in
+ * as soon as other commands are drained.
+ *
+ * LOCKING:
+ * spin_lock_irqsave(host_set lock)
+ */
+void ata_eh_schedule_qc(struct ata_queued_cmd *qc)
+{
+ struct ata_port *ap = qc->ap;
+
+ WARN_ON(!ap->ops->error_handler);
+ WARN_ON(qc->flags & ATA_QCFLAG_EH_SCHEDULED ||
+ ap->flags & ATA_FLAG_FROZEN);
+
+ qc->flags |= ATA_QCFLAG_FAILED | ATA_QCFLAG_EH_SCHEDULED;
+ qc->dev->flags |= ATA_DFLAG_FAILED;
+
+ /* The following will fail if timeout has already expired.
+ * ata_scsi_timed_out() will put @qc onto EH. Note that
+ * EH_SCHEDULED flag is unconditionally set after this
+ * function completes.
+ */
+ scsi_eh_schedule_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 3fd31f9..b522aaa 100644
--- a/drivers/scsi/libata.h
+++ b/drivers/scsi/libata.h
@@ -61,6 +61,7 @@ extern int ata_do_reset(struct ata_port
ata_postreset_fn_t postreset, 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);
@@ -104,5 +105,6 @@ extern void ata_scsi_rbuf_fill(struct at
/* libata-eh.c */
extern enum scsi_eh_timer_return ata_scsi_timed_out(struct scsi_cmnd *cmd);
+extern void ata_eh_schedule_qc(struct ata_queued_cmd *qc);
#endif /* __LIBATA_H__ */
diff --git a/include/linux/libata.h b/include/linux/libata.h
index e059cd3..8aeead3 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -593,7 +593,7 @@ extern void ata_bmdma_start (struct ata_
extern void ata_bmdma_stop(struct ata_queued_cmd *qc);
extern u8 ata_bmdma_status(struct ata_port *ap);
extern void ata_bmdma_irq_clear(struct ata_port *ap);
-extern void __ata_qc_complete(struct ata_queued_cmd *qc);
+extern void ata_qc_complete(struct ata_queued_cmd *qc);
extern void ata_scsi_simulate(struct ata_port *ap, struct ata_device *dev,
struct scsi_cmnd *cmd,
void (*done)(struct scsi_cmnd *));
@@ -859,25 +859,6 @@ static inline void ata_qc_reinit(struct
}
/**
- * 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)
- */
-static inline void ata_qc_complete(struct ata_queued_cmd *qc)
-{
- if (unlikely(qc->flags & ATA_QCFLAG_EH_SCHEDULED))
- return;
-
- __ata_qc_complete(qc);
-}
-
-/**
* ata_irq_on - Enable interrupts on a port.
* @ap: Port on which interrupts are enabled.
*
--
1.2.4
-
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