[PATCH] libata: make the owner of a qc responsible for freeing it

qc used to be freed automatically on command completion.  However, as
a qc can carry information about its completion status, it can be
useful to its owner/issuer after command completion.  This patch makes
freeing qc responsibility of its owner.  This simplifies
ata_exec_internal() and makes command turn-around for atapi request
sensing less hackish.

This change was originally suggested by Jeff Garzik.

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

2 files changed, 20 insertions, 41 deletions

diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index 0e4932362949..15df633521d0 100644
--- a/drivers/scsi/libata-core.c
+++ b/drivers/scsi/libata-core.c
@@ -1072,24 +1072,12 @@ static unsigned int ata_pio_modes(const struct ata_device *adev)
            timing API will get this right anyway */
 }
 
-struct ata_exec_internal_arg {
-        unsigned int err_mask;
-        struct ata_taskfile *tf;
-        struct completion *waiting;
-};
-
-int ata_qc_complete_internal(struct ata_queued_cmd *qc)
+void ata_qc_complete_internal(struct ata_queued_cmd *qc)
 {
-        struct ata_exec_internal_arg *arg = qc->private_data;
-        struct completion *waiting = arg->waiting;
+        struct completion *waiting = qc->private_data;
 
-        if (!(qc->err_mask & ~AC_ERR_DEV))
-                qc->ap->ops->tf_read(qc->ap, arg->tf);
-        arg->err_mask = qc->err_mask;
-        arg->waiting = NULL;
+        qc->ap->ops->tf_read(qc->ap, &qc->tf);
         complete(waiting);
-
-        return 0;
 }
 
 /**
@@ -1120,7 +1108,7 @@ ata_exec_internal(struct ata_port *ap, struct ata_device *dev,
         struct ata_queued_cmd *qc;
         DECLARE_COMPLETION(wait);
         unsigned long flags;
-        struct ata_exec_internal_arg arg;
+        unsigned int err_mask;
 
         spin_lock_irqsave(&ap->host_set->lock, flags);
 
@@ -1134,9 +1122,7 @@ ata_exec_internal(struct ata_port *ap, struct ata_device *dev,
                 qc->nsect = buflen / ATA_SECT_SIZE;
         }
 
-        arg.waiting = &wait;
-        arg.tf = tf;
-        qc->private_data = &arg;
+        qc->private_data = &wait;
         qc->complete_fn = ata_qc_complete_internal;
 
         if (ata_qc_issue(qc))
@@ -1153,7 +1139,7 @@ ata_exec_internal(struct ata_port *ap, struct ata_device *dev,
                  * before the caller cleans up, it will result in a
                  * spurious interrupt.  We can live with that.
                  */
-                if (arg.waiting) {
+                if (qc->flags & ATA_QCFLAG_ACTIVE) {
                         qc->err_mask = AC_ERR_OTHER;
                         ata_qc_complete(qc);
                         printk(KERN_WARNING "ata%u: qc timeout (cmd 0x%x)\n",
@@ -1163,7 +1149,12 @@ ata_exec_internal(struct ata_port *ap, struct ata_device *dev,
                 spin_unlock_irqrestore(&ap->host_set->lock, flags);
         }
 
-        return arg.err_mask;
+        *tf = qc->tf;
+        err_mask = qc->err_mask;
+
+        ata_qc_free(qc);
+
+        return err_mask;
 
  issue_fail:
         ata_qc_free(qc);
@@ -3633,8 +3624,6 @@ void ata_qc_free(struct ata_queued_cmd *qc)
 
 void ata_qc_complete(struct ata_queued_cmd *qc)
 {
-        int rc;
-
         assert(qc != NULL);     /* ata_qc_from_tag _might_ return NULL */
         assert(qc->flags & ATA_QCFLAG_ACTIVE);
 
@@ -3648,17 +3637,7 @@ void ata_qc_complete(struct ata_queued_cmd *qc)
         qc->flags &= ~ATA_QCFLAG_ACTIVE;
 
         /* call completion callback */
-        rc = qc->complete_fn(qc);
-
-        /* if callback indicates not to complete command (non-zero),
-         * return immediately
-         */
-        if (rc != 0)
-                return;
-
-        ata_qc_free(qc);
-
-        VPRINTK("EXIT\n");
+        qc->complete_fn(qc);
 }
 
 static inline int ata_should_dma_map(struct ata_queued_cmd *qc)
diff --git a/drivers/scsi/libata-scsi.c b/drivers/scsi/libata-scsi.c
index 0e65bfe92e6f..ce3fe928a386 100644
--- a/drivers/scsi/libata-scsi.c
+++ b/drivers/scsi/libata-scsi.c
@@ -1219,7 +1219,7 @@ nothing_to_do:
         return 1;
 }
 
-static int ata_scsi_qc_complete(struct ata_queued_cmd *qc)
+static void ata_scsi_qc_complete(struct ata_queued_cmd *qc)
 {
         struct scsi_cmnd *cmd = qc->scsicmd;
         u8 *cdb = cmd->cmnd;
@@ -1256,7 +1256,7 @@ static int ata_scsi_qc_complete(struct ata_queued_cmd *qc)
 
         qc->scsidone(cmd);
 
-        return 0;
+        ata_qc_free(qc);
 }
 
 /**
@@ -1982,7 +1982,7 @@ void ata_scsi_badcmd(struct scsi_cmnd *cmd, void (*done)(struct scsi_cmnd *), u8
         done(cmd);
 }
 
-static int atapi_sense_complete(struct ata_queued_cmd *qc)
+static void atapi_sense_complete(struct ata_queued_cmd *qc)
 {
         if (qc->err_mask && ((qc->err_mask & AC_ERR_DEV) == 0))
                 /* FIXME: not quite right; we don't want the
@@ -1993,7 +1993,7 @@ static int atapi_sense_complete(struct ata_queued_cmd *qc)
                 ata_gen_ata_desc_sense(qc);
 
         qc->scsidone(qc->scsicmd);
-        return 0;
+        ata_qc_free(qc);
 }
 
 /* is it pointless to prefer PIO for "safety reasons"? */
@@ -2050,7 +2050,7 @@ static void atapi_request_sense(struct ata_queued_cmd *qc)
         DPRINTK("EXIT\n");
 }
 
-static int atapi_qc_complete(struct ata_queued_cmd *qc)
+static void atapi_qc_complete(struct ata_queued_cmd *qc)
 {
         struct scsi_cmnd *cmd = qc->scsicmd;
         unsigned int err_mask = qc->err_mask;
@@ -2060,7 +2060,7 @@ static int atapi_qc_complete(struct ata_queued_cmd *qc)
         if (unlikely(err_mask & AC_ERR_DEV)) {
                 cmd->result = SAM_STAT_CHECK_CONDITION;
                 atapi_request_sense(qc);
-                return 1;
+                return;
         }
 
         else if (unlikely(err_mask))
@@ -2100,7 +2100,7 @@ static int atapi_qc_complete(struct ata_queued_cmd *qc)
         }
 
         qc->scsidone(cmd);
-        return 0;
+        ata_qc_free(qc);
 }
 /**
  *      atapi_xlat - Initialize PACKET taskfile