[PATCH] libata: fix command queue leak when xlat_func fails

ata_scsi_translate allocates from the libata command queue by calling
ata_scsi_qc_new.  If xlat_func returns non-zero, control jumps to
err_out which fails to free the allocated command.  Fix is to add a
new API to free unused commands.
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>

drivers/scsi/libata-core.c

@@ -2751,6 +2751,24 @@ static void __ata_qc_complete(struct ata_queued_cmd *qc)
 		clear_bit(tag, &ap->qactive);
 }
 
+/**
+ *	ata_qc_free - free unused ata_queued_cmd
+ *	@qc: Command to complete
+ *
+ *	Designed to free unused ata_queued_cmd object
+ *	in case something prevents using it.
+ *
+ *	LOCKING:
+ *
+ */
+void ata_qc_free(struct ata_queued_cmd *qc)
+{
+	assert(qc != NULL);	/* ata_qc_from_tag _might_ return NULL */
+	assert(qc->waiting == NULL);	/* nothing should be waiting */
+
+	__ata_qc_complete(qc);
+}
+
 /**
  *	ata_qc_complete - Complete an active ATA command
  *	@qc: Command to complete

drivers/scsi/libata-scsi.c

@@ -701,6 +701,7 @@ static void ata_scsi_translate(struct ata_port *ap, struct ata_device *dev,
 	return;
 
 err_out:
+	ata_qc_free(qc);
 	ata_bad_cdb(cmd, done);
 	DPRINTK("EXIT - badcmd\n");
 }

drivers/scsi/libata.h

@@ -37,6 +37,7 @@ struct ata_scsi_args {
 /* libata-core.c */
 extern struct ata_queued_cmd *ata_qc_new_init(struct ata_port *ap,
 				      struct ata_device *dev);
+extern void ata_qc_free(struct ata_queued_cmd *qc);
 extern int ata_qc_issue(struct ata_queued_cmd *qc);
 extern int ata_check_atapi_dma(struct ata_queued_cmd *qc);
 extern void ata_dev_select(struct ata_port *ap, unsigned int device,