[PATCH] libata: pass qc around intead of ap during PIO

The current code passes pointer to ap around and repeatedly performs
ata_qc_from_tag() to access the ongoing qc.  This is unnatural and
makes EH synchronization cumbersome.  Make PIO codes deal with qc
instead of ap.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

1 files changed, 26 insertions, 45 deletions

diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index 007d18888045..e9002a4174d0 100644
--- a/drivers/scsi/libata-core.c
+++ b/drivers/scsi/libata-core.c
@@ -3416,7 +3416,7 @@ void ata_poll_qc_complete(struct ata_queued_cmd *qc)
 
 /**
  *      ata_pio_poll - poll using PIO, depending on current state
- *      @ap: the target ata_port
+ *      @qc: qc in progress
  *
  *      LOCKING:
  *      None.  (executing in kernel thread context)
@@ -3424,17 +3424,13 @@ void ata_poll_qc_complete(struct ata_queued_cmd *qc)
  *      RETURNS:
  *      timeout value to use
  */
-
-static unsigned long ata_pio_poll(struct ata_port *ap)
+static unsigned long ata_pio_poll(struct ata_queued_cmd *qc)
 {
-        struct ata_queued_cmd *qc;
+        struct ata_port *ap = qc->ap;
         u8 status;
         unsigned int poll_state = HSM_ST_UNKNOWN;
         unsigned int reg_state = HSM_ST_UNKNOWN;
 
-        qc = ata_qc_from_tag(ap, ap->active_tag);
-        WARN_ON(qc == NULL);
-
         switch (ap->hsm_task_state) {
         case HSM_ST:
         case HSM_ST_POLL:
@@ -3468,7 +3464,7 @@ static unsigned long ata_pio_poll(struct ata_port *ap)
 
 /**
  *      ata_pio_complete - check if drive is busy or idle
- *      @ap: the target ata_port
+ *      @qc: qc to complete
  *
  *      LOCKING:
  *      None.  (executing in kernel thread context)
@@ -3476,10 +3472,9 @@ static unsigned long ata_pio_poll(struct ata_port *ap)
  *      RETURNS:
  *      Non-zero if qc completed, zero otherwise.
  */
-
-static int ata_pio_complete (struct ata_port *ap)
+static int ata_pio_complete(struct ata_queued_cmd *qc)
 {
-        struct ata_queued_cmd *qc;
+        struct ata_port *ap = qc->ap;
         u8 drv_stat;
 
         /*
@@ -3500,9 +3495,6 @@ static int ata_pio_complete (struct ata_port *ap)
                 }
         }
 
-        qc = ata_qc_from_tag(ap, ap->active_tag);
-        WARN_ON(qc == NULL);
-
         drv_stat = ata_wait_idle(ap);
         if (!ata_ok(drv_stat)) {
                 qc->err_mask |= __ac_err_mask(drv_stat);
@@ -3838,15 +3830,14 @@ err_out:
 
 /**
  *      ata_pio_block - start PIO on a block
- *      @ap: the target ata_port
+ *      @qc: qc to transfer block for
  *
  *      LOCKING:
  *      None.  (executing in kernel thread context)
  */
-
-static void ata_pio_block(struct ata_port *ap)
+static void ata_pio_block(struct ata_queued_cmd *qc)
 {
-        struct ata_queued_cmd *qc;
+        struct ata_port *ap = qc->ap;
         u8 status;
 
         /*
@@ -3868,9 +3859,6 @@ static void ata_pio_block(struct ata_port *ap)
                 }
         }
 
-        qc = ata_qc_from_tag(ap, ap->active_tag);
-        WARN_ON(qc == NULL);
-
         /* check error */
         if (status & (ATA_ERR | ATA_DF)) {
                 qc->err_mask |= AC_ERR_DEV;
@@ -3899,12 +3887,9 @@ static void ata_pio_block(struct ata_port *ap)
         }
 }
 
-static void ata_pio_error(struct ata_port *ap)
+static void ata_pio_error(struct ata_queued_cmd *qc)
 {
-        struct ata_queued_cmd *qc;
-
-        qc = ata_qc_from_tag(ap, ap->active_tag);
-        WARN_ON(qc == NULL);
+        struct ata_port *ap = qc->ap;
 
         if (qc->tf.command != ATA_CMD_PACKET)
                 printk(KERN_WARNING "ata%u: dev %u PIO error\n",
@@ -3922,7 +3907,8 @@ static void ata_pio_error(struct ata_port *ap)
 
 static void ata_pio_task(void *_data)
 {
-        struct ata_port *ap = _data;
+        struct ata_queued_cmd *qc = _data;
+        struct ata_port *ap = qc->ap;
         unsigned long timeout;
         int qc_completed;
 
@@ -3935,33 +3921,33 @@ fsm_start:
                 return;
 
         case HSM_ST:
-                ata_pio_block(ap);
+                ata_pio_block(qc);
                 break;
 
         case HSM_ST_LAST:
-                qc_completed = ata_pio_complete(ap);
+                qc_completed = ata_pio_complete(qc);
                 break;
 
         case HSM_ST_POLL:
         case HSM_ST_LAST_POLL:
-                timeout = ata_pio_poll(ap);
+                timeout = ata_pio_poll(qc);
                 break;
 
         case HSM_ST_TMOUT:
         case HSM_ST_ERR:
-                ata_pio_error(ap);
+                ata_pio_error(qc);
                 return;
         }
 
         if (timeout)
-                ata_port_queue_task(ap, ata_pio_task, ap, timeout);
+                ata_port_queue_task(ap, ata_pio_task, qc, timeout);
         else if (!qc_completed)
                 goto fsm_start;
 }
 
 /**
  *      atapi_packet_task - Write CDB bytes to hardware
- *      @_data: Port to which ATAPI device is attached.
+ *      @_data: qc in progress
  *
  *      When device has indicated its readiness to accept
  *      a CDB, this function is called.  Send the CDB.
@@ -3972,17 +3958,12 @@ fsm_start:
  *      LOCKING:
  *      Kernel thread context (may sleep)
  */
-
 static void atapi_packet_task(void *_data)
 {
-        struct ata_port *ap = _data;
-        struct ata_queued_cmd *qc;
+        struct ata_queued_cmd *qc = _data;
+        struct ata_port *ap = qc->ap;
         u8 status;
 
-        qc = ata_qc_from_tag(ap, ap->active_tag);
-        WARN_ON(qc == NULL);
-        WARN_ON(!(qc->flags & ATA_QCFLAG_ACTIVE));
-
         /* sleep-wait for BSY to clear */
         DPRINTK("busy wait\n");
         if (ata_busy_sleep(ap, ATA_TMOUT_CDB_QUICK, ATA_TMOUT_CDB)) {
@@ -4022,7 +4003,7 @@ static void atapi_packet_task(void *_data)
 
                 /* PIO commands are handled by polling */
                 ap->hsm_task_state = HSM_ST;
-                ata_port_queue_task(ap, ata_pio_task, ap, 0);
+                ata_port_queue_task(ap, ata_pio_task, qc, 0);
         }
 
         return;
@@ -4328,26 +4309,26 @@ unsigned int ata_qc_issue_prot(struct ata_queued_cmd *qc)
                 ata_qc_set_polling(qc);
                 ata_tf_to_host(ap, &qc->tf);
                 ap->hsm_task_state = HSM_ST;
-                ata_port_queue_task(ap, ata_pio_task, ap, 0);
+                ata_port_queue_task(ap, ata_pio_task, qc, 0);
                 break;
 
         case ATA_PROT_ATAPI:
                 ata_qc_set_polling(qc);
                 ata_tf_to_host(ap, &qc->tf);
-                ata_port_queue_task(ap, atapi_packet_task, ap, 0);
+                ata_port_queue_task(ap, atapi_packet_task, qc, 0);
                 break;
 
         case ATA_PROT_ATAPI_NODATA:
                 ap->flags |= ATA_FLAG_NOINTR;
                 ata_tf_to_host(ap, &qc->tf);
-                ata_port_queue_task(ap, atapi_packet_task, ap, 0);
+                ata_port_queue_task(ap, atapi_packet_task, qc, 0);
                 break;
 
         case ATA_PROT_ATAPI_DMA:
                 ap->flags |= ATA_FLAG_NOINTR;
                 ap->ops->tf_load(ap, &qc->tf);   /* load tf registers */
                 ap->ops->bmdma_setup(qc);           /* set up bmdma */
-                ata_port_queue_task(ap, atapi_packet_task, ap, 0);
+                ata_port_queue_task(ap, atapi_packet_task, qc, 0);
                 break;
 
         default: