[PATCH] libata: implement and apply ata_eh_qc_complete/retry()

Implement ata_eh_qc_complete/retry() using scsi_eh_finish_cmd() and
scsi_eh_flush_done_q().  This removes all eh scsicmd finish hacks from
low level drivers.

This change was first suggested by Jeff Garzik.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>

8 files changed, 70 insertions, 64 deletions

diff --git a/drivers/scsi/ahci.c b/drivers/scsi/ahci.c
index 0f6e4dd22901..5a6b23009897 100644
--- a/drivers/scsi/ahci.c
+++ b/drivers/scsi/ahci.c
@@ -672,19 +672,13 @@ static void ahci_eng_timeout(struct ata_port *ap)
                        ap->id);
         } else {
                 ahci_restart_port(ap, readl(port_mmio + PORT_IRQ_STAT));
-
-                /* hack alert!  We cannot use the supplied completion
-                 * function from inside the ->eh_strategy_handler() thread.
-                 * libata is the only user of ->eh_strategy_handler() in
-                 * any kernel, so the default scsi_done() assumes it is
-                 * not being called from the SCSI EH.
-                 */
-                qc->scsidone = scsi_finish_command;
                 qc->err_mask |= AC_ERR_TIMEOUT;
-                ata_qc_complete(qc);
         }
 
         spin_unlock_irqrestore(&host_set->lock, flags);
+
+        if (qc)
+                ata_eh_qc_complete(qc);
 }
 
 static inline int ahci_host_intr(struct ata_port *ap, struct ata_queued_cmd *qc)
diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index b29bf0dc948a..93ae2dcc837c 100644
--- a/drivers/scsi/libata-core.c
+++ b/drivers/scsi/libata-core.c
@@ -3449,14 +3449,6 @@ static void ata_qc_timeout(struct ata_queued_cmd *qc)
 
         spin_lock_irqsave(&host_set->lock, flags);
 
-        /* hack alert!  We cannot use the supplied completion
-         * function from inside the ->eh_strategy_handler() thread.
-         * libata is the only user of ->eh_strategy_handler() in
-         * any kernel, so the default scsi_done() assumes it is
-         * not being called from the SCSI EH.
-         */
-        qc->scsidone = scsi_finish_command;
-
         switch (qc->tf.protocol) {
 
         case ATA_PROT_DMA:
@@ -3480,12 +3472,13 @@ static void ata_qc_timeout(struct ata_queued_cmd *qc)
 
                 /* complete taskfile transaction */
                 qc->err_mask |= ac_err_mask(drv_stat);
-                ata_qc_complete(qc);
                 break;
         }
 
         spin_unlock_irqrestore(&host_set->lock, flags);
 
+        ata_eh_qc_complete(qc);
+
         DPRINTK("EXIT\n");
 }
 
@@ -4422,6 +4415,7 @@ static void ata_host_init(struct ata_port *ap, struct Scsi_Host *host,
 
         INIT_WORK(&ap->packet_task, atapi_packet_task, ap);
         INIT_WORK(&ap->pio_task, ata_pio_task, ap);
+        INIT_LIST_HEAD(&ap->eh_done_q);
 
         for (i = 0; i < ATA_MAX_DEVICES; i++)
                 ap->device[i].devno = i;
@@ -5165,6 +5159,8 @@ EXPORT_SYMBOL_GPL(ata_dev_classify);
 EXPORT_SYMBOL_GPL(ata_dev_id_string);
 EXPORT_SYMBOL_GPL(ata_dev_config);
 EXPORT_SYMBOL_GPL(ata_scsi_simulate);
+EXPORT_SYMBOL_GPL(ata_eh_qc_complete);
+EXPORT_SYMBOL_GPL(ata_eh_qc_retry);
 
 EXPORT_SYMBOL_GPL(ata_pio_need_iordy);
 EXPORT_SYMBOL_GPL(ata_timing_compute);
diff --git a/drivers/scsi/libata-scsi.c b/drivers/scsi/libata-scsi.c
index 95e3c278dd43..ab6b53349d6f 100644
--- a/drivers/scsi/libata-scsi.c
+++ b/drivers/scsi/libata-scsi.c
@@ -738,17 +738,64 @@ int ata_scsi_error(struct Scsi_Host *host)
         ap = (struct ata_port *) &host->hostdata[0];
         ap->ops->eng_timeout(ap);
 
-        /* TODO: this is per-command; when queueing is supported
-         * this code will either change or move to a more
-         * appropriate place
-         */
-        host->host_failed--;
-        INIT_LIST_HEAD(&host->eh_cmd_q);
+        assert(host->host_failed == 0 && list_empty(&host->eh_cmd_q));
+
+        scsi_eh_flush_done_q(&ap->eh_done_q);
 
         DPRINTK("EXIT\n");
         return 0;
 }
 
+static void ata_eh_scsidone(struct scsi_cmnd *scmd)
+{
+        /* nada */
+}
+
+static void __ata_eh_qc_complete(struct ata_queued_cmd *qc)
+{
+        struct ata_port *ap = qc->ap;
+        struct scsi_cmnd *scmd = qc->scsicmd;
+        unsigned long flags;
+
+        spin_lock_irqsave(&ap->host_set->lock, flags);
+        qc->scsidone = ata_eh_scsidone;
+        ata_qc_complete(qc);
+        assert(!ata_tag_valid(qc->tag));
+        spin_unlock_irqrestore(&ap->host_set->lock, flags);
+
+        scsi_eh_finish_cmd(scmd, &ap->eh_done_q);
+}
+
+/**
+ *      ata_eh_qc_complete - Complete an active ATA command from EH
+ *      @qc: Command to complete
+ *
+ *      Indicate to the mid and upper layers that an ATA command has
+ *      completed.  To be used from EH.
+ */
+void ata_eh_qc_complete(struct ata_queued_cmd *qc)
+{
+        struct scsi_cmnd *scmd = qc->scsicmd;
+        scmd->retries = scmd->allowed;
+        __ata_eh_qc_complete(qc);
+}
+
+/**
+ *      ata_eh_qc_retry - Tell midlayer to retry an ATA command after EH
+ *      @qc: Command to retry
+ *
+ *      Indicate to the mid and upper layers that an ATA command
+ *      should be retried.  To be used from EH.
+ *
+ *      SCSI midlayer limits the number of retries to scmd->allowed.
+ *      This function might need to adjust scmd->retries for commands
+ *      which get retried due to unrelated NCQ failures.
+ */
+void ata_eh_qc_retry(struct ata_queued_cmd *qc)
+{
+        __ata_eh_qc_complete(qc);
+}
+
 /**
  *      ata_scsi_start_stop_xlat - Translate SCSI START STOP UNIT command
  *      @qc: Storage for translated ATA taskfile
diff --git a/drivers/scsi/sata_mv.c b/drivers/scsi/sata_mv.c
index 281223a0e45f..d9a554ca45c7 100644
--- a/drivers/scsi/sata_mv.c
+++ b/drivers/scsi/sata_mv.c
@@ -1839,7 +1839,6 @@ static void mv_phy_reset(struct ata_port *ap)
 static void mv_eng_timeout(struct ata_port *ap)
 {
         struct ata_queued_cmd *qc;
-        unsigned long flags;
 
         printk(KERN_ERR "ata%u: Entering mv_eng_timeout\n",ap->id);
         DPRINTK("All regs @ start of eng_timeout\n");
@@ -1858,17 +1857,8 @@ static void mv_eng_timeout(struct ata_port *ap)
                 printk(KERN_ERR "ata%u: BUG: timeout without command\n",
                        ap->id);
         } else {
-                /* hack alert!  We cannot use the supplied completion
-                 * function from inside the ->eh_strategy_handler() thread.
-                 * libata is the only user of ->eh_strategy_handler() in
-                 * any kernel, so the default scsi_done() assumes it is
-                 * not being called from the SCSI EH.
-                 */
-                spin_lock_irqsave(&ap->host_set->lock, flags);
-                qc->scsidone = scsi_finish_command;
                 qc->err_mask |= AC_ERR_TIMEOUT;
-                ata_qc_complete(qc);
-                spin_unlock_irqrestore(&ap->host_set->lock, flags);
+                ata_eh_qc_complete(qc);
         }
 }
 
diff --git a/drivers/scsi/sata_promise.c b/drivers/scsi/sata_promise.c
index bac36d5b7c3e..77ef646b0f92 100644
--- a/drivers/scsi/sata_promise.c
+++ b/drivers/scsi/sata_promise.c
@@ -400,21 +400,12 @@ static void pdc_eng_timeout(struct ata_port *ap)
                 goto out;
         }
 
-        /* hack alert!  We cannot use the supplied completion
-         * function from inside the ->eh_strategy_handler() thread.
-         * libata is the only user of ->eh_strategy_handler() in
-         * any kernel, so the default scsi_done() assumes it is
-         * not being called from the SCSI EH.
-         */
-        qc->scsidone = scsi_finish_command;
-
         switch (qc->tf.protocol) {
         case ATA_PROT_DMA:
         case ATA_PROT_NODATA:
                 printk(KERN_ERR "ata%u: command timeout\n", ap->id);
                 drv_stat = ata_wait_idle(ap);
                 qc->err_mask |= __ac_err_mask(drv_stat);
-                ata_qc_complete(qc);
                 break;
 
         default:
@@ -424,12 +415,13 @@ static void pdc_eng_timeout(struct ata_port *ap)
                        ap->id, qc->tf.command, drv_stat);
 
                 qc->err_mask |= ac_err_mask(drv_stat);
-                ata_qc_complete(qc);
                 break;
         }
 
 out:
         spin_unlock_irqrestore(&host_set->lock, flags);
+        if (qc)
+                ata_eh_qc_complete(qc);
         DPRINTK("EXIT\n");
 }
 
diff --git a/drivers/scsi/sata_sil24.c b/drivers/scsi/sata_sil24.c
index 5a7a7b1d4add..7222fc7ff3fc 100644
--- a/drivers/scsi/sata_sil24.c
+++ b/drivers/scsi/sata_sil24.c
@@ -644,17 +644,9 @@ static void sil24_eng_timeout(struct ata_port *ap)
                 return;
         }
 
-        /*
-         * hack alert!  We cannot use the supplied completion
-         * function from inside the ->eh_strategy_handler() thread.
-         * libata is the only user of ->eh_strategy_handler() in
-         * any kernel, so the default scsi_done() assumes it is
-         * not being called from the SCSI EH.
-         */
         printk(KERN_ERR "ata%u: command timeout\n", ap->id);
-        qc->scsidone = scsi_finish_command;
         qc->err_mask |= AC_ERR_TIMEOUT;
-        ata_qc_complete(qc);
+        ata_eh_qc_complete(qc);
 
         sil24_reset_controller(ap);
 }
diff --git a/drivers/scsi/sata_sx4.c b/drivers/scsi/sata_sx4.c
index 3175c6bb4fec..9f992fbcf2e7 100644
--- a/drivers/scsi/sata_sx4.c
+++ b/drivers/scsi/sata_sx4.c
@@ -872,20 +872,11 @@ static void pdc_eng_timeout(struct ata_port *ap)
                 goto out;
         }
 
-        /* hack alert!  We cannot use the supplied completion
-         * function from inside the ->eh_strategy_handler() thread.
-         * libata is the only user of ->eh_strategy_handler() in
-         * any kernel, so the default scsi_done() assumes it is
-         * not being called from the SCSI EH.
-         */
-        qc->scsidone = scsi_finish_command;
-
         switch (qc->tf.protocol) {
         case ATA_PROT_DMA:
         case ATA_PROT_NODATA:
                 printk(KERN_ERR "ata%u: command timeout\n", ap->id);
                 qc->err_mask |= __ac_err_mask(ata_wait_idle(ap));
-                ata_qc_complete(qc);
                 break;
 
         default:
@@ -895,12 +886,13 @@ static void pdc_eng_timeout(struct ata_port *ap)
                        ap->id, qc->tf.command, drv_stat);
 
                 qc->err_mask |= ac_err_mask(drv_stat);
-                ata_qc_complete(qc);
                 break;
         }
 
 out:
         spin_unlock_irqrestore(&host_set->lock, flags);
+        if (qc)
+                ata_eh_qc_complete(qc);
         DPRINTK("EXIT\n");
 }
 
diff --git a/include/linux/libata.h b/include/linux/libata.h
index b1ea2f98bfbb..576788de962a 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -398,6 +398,7 @@ struct ata_port {
         unsigned long           pio_task_timeout;
 
         u32                     msg_enable;
+        struct list_head        eh_done_q;
 
         void                    *private_data;
 };
@@ -490,6 +491,8 @@ extern int ata_scsi_detect(struct scsi_host_template *sht);
 extern int ata_scsi_ioctl(struct scsi_device *dev, int cmd, void __user *arg);
 extern int ata_scsi_queuecmd(struct scsi_cmnd *cmd, void (*done)(struct scsi_cmnd *));
 extern int ata_scsi_error(struct Scsi_Host *host);
+extern void ata_eh_qc_complete(struct ata_queued_cmd *qc);
+extern void ata_eh_qc_retry(struct ata_queued_cmd *qc);
 extern int ata_scsi_release(struct Scsi_Host *host);
 extern unsigned int ata_host_intr(struct ata_port *ap, struct ata_queued_cmd *qc);
 extern int ata_scsi_device_resume(struct scsi_device *);