[libata] Improve timeout handling

On a timeout call a device specific handler early in the recovery so that
we can complete and process successful commands which timed out due to IRQ
loss or the like rather more elegantly.

[Revised to exclude the timeout handling on a few devices that inherit from
 SFF but are not SFF enough to use the default timeout handler]

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

10 files changed, 85 insertions, 5 deletions

diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index ea890911d4fa..01831312c360 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -547,7 +547,7 @@ void ata_scsi_error(struct Scsi_Host *host)
 
         /* 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
+         * Both completions 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.
          *
@@ -562,7 +562,19 @@ void ata_scsi_error(struct Scsi_Host *host)
                 int nr_timedout = 0;
 
                 spin_lock_irqsave(ap->lock, flags);
-
+                
+                /* This must occur under the ap->lock as we don't want
+                   a polled recovery to race the real interrupt handler
+                   
+                   The lost_interrupt handler checks for any completed but
+                   non-notified command and completes much like an IRQ handler.
+                   
+                   We then fall into the error recovery code which will treat
+                   this as if normal completion won the race */
+
+                if (ap->ops->lost_interrupt)
+                        ap->ops->lost_interrupt(ap);
+                        
                 list_for_each_entry_safe(scmd, tmp, &host->eh_cmd_q, eh_entry) {
                         struct ata_queued_cmd *qc;
 
@@ -606,6 +618,9 @@ void ata_scsi_error(struct Scsi_Host *host)
                 ap->eh_tries = ATA_EH_MAX_TRIES;
         } else
                 spin_unlock_wait(ap->lock);
+                
+        /* If we timed raced normal completion and there is nothing to
+           recover nr_timedout == 0 why exactly are we doing error recovery ? */
 
  repeat:
         /* invoke error handler */
diff --git a/drivers/ata/libata-sff.c b/drivers/ata/libata-sff.c
index 9a10cb055ac2..8332e97a9de3 100644
--- a/drivers/ata/libata-sff.c
+++ b/drivers/ata/libata-sff.c
@@ -65,6 +65,8 @@ const struct ata_port_operations ata_sff_port_ops = {
         .sff_irq_on             = ata_sff_irq_on,
         .sff_irq_clear          = ata_sff_irq_clear,
 
+        .lost_interrupt         = ata_sff_lost_interrupt,
+
         .port_start             = ata_sff_port_start,
 };
 EXPORT_SYMBOL_GPL(ata_sff_port_ops);
@@ -1647,7 +1649,7 @@ EXPORT_SYMBOL_GPL(ata_sff_qc_fill_rtf);
  *      RETURNS:
  *      One if interrupt was handled, zero if not (shared irq).
  */
-inline unsigned int ata_sff_host_intr(struct ata_port *ap,
+unsigned int ata_sff_host_intr(struct ata_port *ap,
                                       struct ata_queued_cmd *qc)
 {
         struct ata_eh_info *ehi = &ap->link.eh_info;
@@ -1776,6 +1778,48 @@ irqreturn_t ata_sff_interrupt(int irq, void *dev_instance)
 EXPORT_SYMBOL_GPL(ata_sff_interrupt);
 
 /**
+ *      ata_sff_lost_interrupt  -       Check for an apparent lost interrupt
+ *      @ap: port that appears to have timed out
+ *
+ *      Called from the libata error handlers when the core code suspects
+ *      an interrupt has been lost. If it has complete anything we can and
+ *      then return. Interface must support altstatus for this faster
+ *      recovery to occur.
+ *
+ *      Locking:
+ *      Caller holds host lock
+ */
+
+void ata_sff_lost_interrupt(struct ata_port *ap)
+{
+        u8 status;
+        struct ata_queued_cmd *qc;
+
+        /* Only one outstanding command per SFF channel */
+        qc = ata_qc_from_tag(ap, ap->link.active_tag);
+        /* Check we have a live one.. */
+        if (qc == NULL ||  !(qc->flags & ATA_QCFLAG_ACTIVE))
+                return;
+        /* We cannot lose an interrupt on a polled command */
+        if (qc->tf.flags & ATA_TFLAG_POLLING)
+                return;
+        /* See if the controller thinks it is still busy - if so the command
+           isn't a lost IRQ but is still in progress */
+        status = ata_sff_altstatus(ap);
+        if (status & ATA_BUSY)
+                return;
+
+        /* There was a command running, we are no longer busy and we have
+           no interrupt. */
+        ata_port_printk(ap, KERN_WARNING, "lost interrupt (Status 0x%x)\n",
+                                                                status);
+        /* Run the host interrupt logic as if the interrupt had not been
+           lost */
+        ata_sff_host_intr(ap, qc);
+}
+EXPORT_SYMBOL_GPL(ata_sff_lost_interrupt);
+
+/**
  *      ata_sff_freeze - Freeze SFF controller port
  *      @ap: port to freeze
  *
diff --git a/drivers/ata/pata_isapnp.c b/drivers/ata/pata_isapnp.c
index afa8f704271e..4bceb8803a10 100644
--- a/drivers/ata/pata_isapnp.c
+++ b/drivers/ata/pata_isapnp.c
@@ -17,7 +17,7 @@
 #include <linux/libata.h>
 
 #define DRV_NAME "pata_isapnp"
-#define DRV_VERSION "0.2.2"
+#define DRV_VERSION "0.2.5"
 
 static struct scsi_host_template isapnp_sht = {
         ATA_PIO_SHT(DRV_NAME),
@@ -28,6 +28,13 @@ static struct ata_port_operations isapnp_port_ops = {
         .cable_detect   = ata_cable_40wire,
 };
 
+static struct ata_port_operations isapnp_noalt_port_ops = {
+        .inherits       = &ata_sff_port_ops,
+        .cable_detect   = ata_cable_40wire,
+        /* No altstatus so we don't want to use the lost interrupt poll */
+        .lost_interrupt = ATA_OP_NULL,
+};
+
 /**
  *      isapnp_init_one         -       attach an isapnp interface
  *      @idev: PnP device
@@ -65,7 +72,7 @@ static int isapnp_init_one(struct pnp_dev *idev, const struct pnp_device_id *dev
 
         ap = host->ports[0];
 
-        ap->ops = &isapnp_port_ops;
+        ap->ops = &isapnp_noalt_port_ops;
         ap->pio_mask = ATA_PIO0;
         ap->flags |= ATA_FLAG_SLAVE_POSS;
 
@@ -76,6 +83,7 @@ static int isapnp_init_one(struct pnp_dev *idev, const struct pnp_device_id *dev
                                            pnp_port_start(idev, 1), 1);
                 ap->ioaddr.altstatus_addr = ctl_addr;
                 ap->ioaddr.ctl_addr = ctl_addr;
+                ap->ops = &isapnp_port_ops;
         }
 
         ata_sff_std_ports(&ap->ioaddr);
diff --git a/drivers/ata/pdc_adma.c b/drivers/ata/pdc_adma.c
index c509c206a459..39588178d028 100644
--- a/drivers/ata/pdc_adma.c
+++ b/drivers/ata/pdc_adma.c
@@ -148,6 +148,8 @@ static struct scsi_host_template adma_ata_sht = {
 static struct ata_port_operations adma_ata_ops = {
         .inherits               = &ata_sff_port_ops,
 
+        .lost_interrupt         = ATA_OP_NULL,
+
         .check_atapi_dma        = adma_check_atapi_dma,
         .qc_prep                = adma_qc_prep,
         .qc_issue               = adma_qc_issue,
diff --git a/drivers/ata/sata_mv.c b/drivers/ata/sata_mv.c
index 8a751054c8a1..a377226b81c8 100644
--- a/drivers/ata/sata_mv.c
+++ b/drivers/ata/sata_mv.c
@@ -646,6 +646,8 @@ static struct scsi_host_template mv6_sht = {
 static struct ata_port_operations mv5_ops = {
         .inherits               = &ata_sff_port_ops,
 
+        .lost_interrupt         = ATA_OP_NULL,
+
         .qc_defer               = mv_qc_defer,
         .qc_prep                = mv_qc_prep,
         .qc_issue               = mv_qc_issue,
diff --git a/drivers/ata/sata_nv.c b/drivers/ata/sata_nv.c
index 2f523f8c27f6..6cda12ba8122 100644
--- a/drivers/ata/sata_nv.c
+++ b/drivers/ata/sata_nv.c
@@ -408,6 +408,7 @@ static struct scsi_host_template nv_swncq_sht = {
 
 static struct ata_port_operations nv_common_ops = {
         .inherits               = &ata_bmdma_port_ops,
+        .lost_interrupt         = ATA_OP_NULL,
         .scr_read               = nv_scr_read,
         .scr_write              = nv_scr_write,
 };
diff --git a/drivers/ata/sata_promise.c b/drivers/ata/sata_promise.c
index 3ad2b8863636..b1fd7d62071a 100644
--- a/drivers/ata/sata_promise.c
+++ b/drivers/ata/sata_promise.c
@@ -176,7 +176,9 @@ static const struct ata_port_operations pdc_common_ops = {
         .check_atapi_dma        = pdc_check_atapi_dma,
         .qc_prep                = pdc_qc_prep,
         .qc_issue               = pdc_qc_issue,
+
         .sff_irq_clear          = pdc_irq_clear,
+        .lost_interrupt         = ATA_OP_NULL,
 
         .post_internal_cmd      = pdc_post_internal_cmd,
         .error_handler          = pdc_error_handler,
diff --git a/drivers/ata/sata_qstor.c b/drivers/ata/sata_qstor.c
index 7112d89fd9ff..c3936d35cdac 100644
--- a/drivers/ata/sata_qstor.c
+++ b/drivers/ata/sata_qstor.c
@@ -147,6 +147,7 @@ static struct ata_port_operations qs_ata_ops = {
         .softreset              = ATA_OP_NULL,
         .error_handler          = qs_error_handler,
         .post_internal_cmd      = ATA_OP_NULL,
+        .lost_interrupt         = ATA_OP_NULL,
 
         .scr_read               = qs_scr_read,
         .scr_write              = qs_scr_write,
diff --git a/drivers/ata/sata_vsc.c b/drivers/ata/sata_vsc.c
index ef211f333d7b..ed70bd28fa2c 100644
--- a/drivers/ata/sata_vsc.c
+++ b/drivers/ata/sata_vsc.c
@@ -308,6 +308,9 @@ static struct scsi_host_template vsc_sata_sht = {
 
 static struct ata_port_operations vsc_sata_ops = {
         .inherits               = &ata_bmdma_port_ops,
+        /* The IRQ handling is not quite standard SFF behaviour so we
+           cannot use the default lost interrupt handler */
+        .lost_interrupt         = ATA_OP_NULL,
         .sff_tf_load            = vsc_sata_tf_load,
         .sff_tf_read            = vsc_sata_tf_read,
         .freeze                 = vsc_freeze,
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 3a07a32dfc2e..76262d83656b 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -795,6 +795,7 @@ struct ata_port_operations {
         ata_reset_fn_t          pmp_hardreset;
         ata_postreset_fn_t      pmp_postreset;
         void (*error_handler)(struct ata_port *ap);
+        void (*lost_interrupt)(struct ata_port *ap);
         void (*post_internal_cmd)(struct ata_queued_cmd *qc);
 
         /*
@@ -1577,6 +1578,7 @@ extern bool ata_sff_qc_fill_rtf(struct ata_queued_cmd *qc);
 extern unsigned int ata_sff_host_intr(struct ata_port *ap,
                                       struct ata_queued_cmd *qc);
 extern irqreturn_t ata_sff_interrupt(int irq, void *dev_instance);
+extern void ata_sff_lost_interrupt(struct ata_port *ap);
 extern void ata_sff_freeze(struct ata_port *ap);
 extern void ata_sff_thaw(struct ata_port *ap);
 extern int ata_sff_prereset(struct ata_link *link, unsigned long deadline);