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@xxxxxxxxx>
---
drivers/scsi/libata-eh.c | 136 ++++++++++++++++++++++++++++++++++++++++++++--
include/linux/libata.h | 3 +
2 files changed, 134 insertions(+), 5 deletions(-)
610d1ef7cf0e6a147bc190ebb2f55afabf764df4
diff --git a/drivers/scsi/libata-eh.c b/drivers/scsi/libata-eh.c
index cb4e2b8..0803231 100644
--- a/drivers/scsi/libata-eh.c
+++ b/drivers/scsi/libata-eh.c
@@ -44,6 +44,8 @@
#include "libata.h"
+static void __ata_port_freeze(struct ata_port *ap);
+
/**
* ata_scsi_timed_out - SCSI layer time out callback
* @cmd: timed out SCSI command
@@ -55,6 +57,8 @@
* from finishing it by setting EH_SCHEDULED and return
* EH_NOT_HANDLED.
*
+ * TODO: kill this function once old EH is gone.
+ *
* LOCKING:
* Called from timer context
*
@@ -67,10 +71,16 @@ enum scsi_eh_timer_return ata_scsi_timed
struct ata_port *ap = ata_shost_to_port(host);
unsigned long flags;
struct ata_queued_cmd *qc;
- enum scsi_eh_timer_return ret = EH_HANDLED;
+ enum scsi_eh_timer_return ret;
DPRINTK("ENTER\n");
+ if (ap->ops->error_handler) {
+ ret = EH_NOT_HANDLED;
+ goto out;
+ }
+
+ ret = EH_HANDLED;
spin_lock_irqsave(&ap->host_set->lock, flags);
qc = ata_qc_from_tag(ap, ap->active_tag);
if (qc) {
@@ -81,6 +91,7 @@ enum scsi_eh_timer_return ata_scsi_timed
}
spin_unlock_irqrestore(&ap->host_set->lock, flags);
+ out:
DPRINTK("EXIT, ret=%d\n", ret);
return ret;
}
@@ -100,21 +111,132 @@ enum scsi_eh_timer_return ata_scsi_timed
void ata_scsi_error(struct Scsi_Host *host)
{
struct ata_port *ap = ata_shost_to_port(host);
+ spinlock_t *hs_lock = &ap->host_set->lock;
+ int i, repeat_cnt = ATA_EH_MAX_REPEAT;
+ unsigned long flags;
DPRINTK("ENTER\n");
- /* synchronize with IRQ handler and port task */
- spin_unlock_wait(&ap->host_set->lock);
+ /* synchronize with port task */
ata_port_flush_task(ap);
- WARN_ON(ata_qc_from_tag(ap, ap->active_tag) == NULL);
+ /* synchronize with host_set lock and sort out timeouts */
- ap->ops->eng_timeout(ap);
+ /* For new EH, all qcs are finished in one of three ways -
+ * normal completion, error completion, and SCSI timeout.
+ * Both cmpletions can race against SCSI timeout. When normal
+ * completion wins, the qc never reaches EH. When error
+ * completion wins, the qc has ATA_QCFLAG_FAILED set.
+ *
+ * When SCSI timeout wins, things are a bit more complex.
+ * Normal or error completion can occur after the timeout but
+ * before this point. In such cases, both types of
+ * completions are honored. A scmd is determined to have
+ * timed out iff its associated qc is active and not failed.
+ */
+ if (ap->ops->error_handler) {
+ struct scsi_cmnd *scmd, *tmp;
+ int nr_timedout = 0;
+
+ spin_lock_irqsave(hs_lock, flags);
+
+ list_for_each_entry_safe(scmd, tmp, &host->eh_cmd_q, eh_entry) {
+ struct ata_queued_cmd *qc;
+
+ for (i = 0; i < ATA_MAX_QUEUE; i++) {
+ qc = __ata_qc_from_tag(ap, i);
+ if (qc->flags & ATA_QCFLAG_ACTIVE &&
+ qc->scsicmd == scmd)
+ break;
+ }
+
+ if (i < ATA_MAX_QUEUE) {
+ /* the scmd has an associated qc */
+ if (!(qc->flags & ATA_QCFLAG_FAILED)) {
+ /* which hasn't failed yet, timeout */
+ qc->err_mask |= AC_ERR_TIMEOUT;
+ qc->flags |= ATA_QCFLAG_FAILED;
+ nr_timedout++;
+ }
+ } else {
+ /* Normal completion occurred after
+ * SCSI timeout but before this point.
+ * Successfully complete it.
+ */
+ scmd->retries = scmd->allowed;
+ scsi_eh_finish_cmd(scmd, &ap->eh_done_q);
+ }
+ }
+ /* If we have timed out qcs. They belong to EH from
+ * this point but the state of the controller is
+ * unknown. Freeze the port to make sure the IRQ
+ * handler doesn't diddle with those qcs. This must
+ * be done atomically w.r.t. setting QCFLAG_FAILED.
+ */
+ if (nr_timedout)
+ __ata_port_freeze(ap);
+
+ spin_unlock_irqrestore(hs_lock, flags);
+ } else
+ spin_unlock_wait(hs_lock);
+
+ repeat:
+ /* invoke error handler */
+ if (ap->ops->error_handler) {
+ /* clear EH pending */
+ spin_lock_irqsave(hs_lock, flags);
+ ap->flags &= ~ATA_FLAG_EH_PENDING;
+ spin_unlock_irqrestore(hs_lock, flags);
+
+ /* invoke EH */
+ ap->ops->error_handler(ap);
+
+ /* Exception might have happend after ->error_handler
+ * recovered the port but before this point. Repeat
+ * EH in such case.
+ */
+ spin_lock_irqsave(hs_lock, flags);
+
+ if (ap->flags & ATA_FLAG_EH_PENDING) {
+ if (--repeat_cnt) {
+ ata_port_printk(ap, KERN_INFO,
+ "EH pending after completion, "
+ "repeating EH (cnt=%d)\n", repeat_cnt);
+ spin_unlock_irqrestore(hs_lock, flags);
+ goto repeat;
+ }
+ ata_port_printk(ap, KERN_ERR, "EH pending after %d "
+ "tries, giving up\n", ATA_EH_MAX_REPEAT);
+ }
+
+ /* Clear host_eh_scheduled while holding hs_lock such
+ * that if exception occurs after this point but
+ * before EH completion, SCSI midlayer will
+ * re-initiate EH.
+ */
+ host->host_eh_scheduled = 0;
+
+ spin_unlock_irqrestore(hs_lock, flags);
+ } else {
+ WARN_ON(ata_qc_from_tag(ap, ap->active_tag) == NULL);
+ ap->ops->eng_timeout(ap);
+ }
+
+ /* finish or retry handled scmd's and clean up */
WARN_ON(host->host_failed || !list_empty(&host->eh_cmd_q));
scsi_eh_flush_done_q(&ap->eh_done_q);
+ /* clean up */
+ spin_lock_irqsave(hs_lock, flags);
+
+ if (ap->flags & ATA_FLAG_RECOVERED)
+ ata_port_printk(ap, KERN_INFO, "EH complete\n");
+ ap->flags &= ~ATA_FLAG_RECOVERED;
+
+ spin_unlock_irqrestore(hs_lock, flags);
+
DPRINTK("EXIT\n");
}
@@ -133,6 +255,8 @@ void ata_scsi_error(struct Scsi_Host *ho
* an interrupt was not delivered to the driver, even though the
* transaction completed successfully.
*
+ * TODO: kill this function once old EH is gone.
+ *
* LOCKING:
* Inherited from SCSI layer (none, can sleep)
*/
@@ -198,6 +322,8 @@ static void ata_qc_timeout(struct ata_qu
* an interrupt was not delivered to the driver, even though the
* transaction completed successfully.
*
+ * TODO: kill this function once old EH is gone.
+ *
* LOCKING:
* Inherited from SCSI layer (none, can sleep)
*/
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 3f22eff..e4353cf 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -225,6 +225,9 @@ enum {
ATA_PORT_PRIMARY = (1 << 0),
ATA_PORT_SECONDARY = (1 << 1),
+ /* max repeat if error condition is still set after ->error_handler */
+ ATA_EH_MAX_REPEAT = 5,
+
/* how hard are we gonna try to probe/recover devices */
ATA_PROBE_MAX_TRIES = 3,
};
--
1.2.4
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