scsi: core: Introduce enum scsi_disposition

Improve readability of the code in the SCSI core by introducing an
enumeration type for the values used internally that decide how to continue
processing a SCSI command. The eh_*_handler return values have not been
changed because that would involve modifying all SCSI drivers.

The output of the following command has been inspected to verify that no
out-of-range values are assigned to a variable of type enum
scsi_disposition:

KCFLAGS=-Wassign-enum make CC=clang W=1 drivers/scsi/

Link: https://lore.kernel.org/r/20210415220826.29438-6-bvanassche@acm.org
Cc: Christoph Hellwig <hch@lst.de>
Cc: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Daniel Wagner <dwagner@suse.de>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

7 files changed, 43 insertions, 39 deletions

diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index b6f92050e60c..5352be2b447d 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -1599,7 +1599,7 @@ static unsigned int ata_eh_analyze_tf(struct ata_queued_cmd *qc,
 	}
 
 	if (qc->flags & ATA_QCFLAG_SENSE_VALID) {
-		int ret = scsi_check_sense(qc->scsicmd);
+		enum scsi_disposition ret = scsi_check_sense(qc->scsicmd);
 		/*
 		 * SUCCESS here means that the sense code could be
 		 * evaluated and should be passed to the upper layers
diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c
index e6fde27d4565..efa8c0381476 100644
--- a/drivers/scsi/device_handler/scsi_dh_alua.c
+++ b/drivers/scsi/device_handler/scsi_dh_alua.c
@@ -405,8 +405,8 @@ static char print_alua_state(unsigned char state)
 	}
 }
 
-static int alua_check_sense(struct scsi_device *sdev,
-			    struct scsi_sense_hdr *sense_hdr)
+static enum scsi_disposition alua_check_sense(struct scsi_device *sdev,
+					      struct scsi_sense_hdr *sense_hdr)
 {
 	struct alua_dh_data *h = sdev->handler_data;
 	struct alua_port_group *pg;
diff --git a/drivers/scsi/device_handler/scsi_dh_emc.c b/drivers/scsi/device_handler/scsi_dh_emc.c
index caa685cfe3d4..bd28ec6cfb72 100644
--- a/drivers/scsi/device_handler/scsi_dh_emc.c
+++ b/drivers/scsi/device_handler/scsi_dh_emc.c
@@ -280,8 +280,8 @@ static int send_trespass_cmd(struct scsi_device *sdev,
 	return res;
 }
 
-static int clariion_check_sense(struct scsi_device *sdev,
-				struct scsi_sense_hdr *sense_hdr)
+static enum scsi_disposition clariion_check_sense(struct scsi_device *sdev,
+					struct scsi_sense_hdr *sense_hdr)
 {
 	switch (sense_hdr->sense_key) {
 	case NOT_READY:
diff --git a/drivers/scsi/device_handler/scsi_dh_rdac.c b/drivers/scsi/device_handler/scsi_dh_rdac.c
index 5efc959493ec..25f6e1ac9e7b 100644
--- a/drivers/scsi/device_handler/scsi_dh_rdac.c
+++ b/drivers/scsi/device_handler/scsi_dh_rdac.c
@@ -656,8 +656,8 @@ static blk_status_t rdac_prep_fn(struct scsi_device *sdev, struct request *req)
 	return BLK_STS_OK;
 }
 
-static int rdac_check_sense(struct scsi_device *sdev,
-				struct scsi_sense_hdr *sense_hdr)
+static enum scsi_disposition rdac_check_sense(struct scsi_device *sdev,
+					      struct scsi_sense_hdr *sense_hdr)
 {
 	struct rdac_dh_data *h = sdev->handler_data;
 
diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index 271718e888d1..d8fafe77dbbe 100644
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -60,8 +60,8 @@ static void scsi_eh_done(struct scsi_cmnd *scmd);
 #define HOST_RESET_SETTLE_TIME  (10)
 
 static int scsi_eh_try_stu(struct scsi_cmnd *scmd);
-static int scsi_try_to_abort_cmd(struct scsi_host_template *,
-				 struct scsi_cmnd *);
+static enum scsi_disposition scsi_try_to_abort_cmd(struct scsi_host_template *,
+						   struct scsi_cmnd *);
 
 void scsi_eh_wakeup(struct Scsi_Host *shost)
 {
@@ -151,7 +151,7 @@ scmd_eh_abort_handler(struct work_struct *work)
 	struct scsi_cmnd *scmd =
 		container_of(work, struct scsi_cmnd, abort_work.work);
 	struct scsi_device *sdev = scmd->device;
-	int rtn;
+	enum scsi_disposition rtn;
 
 	if (scsi_host_eh_past_deadline(sdev->host)) {
 		SCSI_LOG_ERROR_RECOVERY(3,
@@ -498,7 +498,7 @@ static void scsi_report_sense(struct scsi_device *sdev,
  *	When a deferred error is detected the current command has
  *	not been executed and needs retrying.
  */
-int scsi_check_sense(struct scsi_cmnd *scmd)
+enum scsi_disposition scsi_check_sense(struct scsi_cmnd *scmd)
 {
 	struct scsi_device *sdev = scmd->device;
 	struct scsi_sense_hdr sshdr;
@@ -512,7 +512,7 @@ int scsi_check_sense(struct scsi_cmnd *scmd)
 		return NEEDS_RETRY;
 
 	if (sdev->handler && sdev->handler->check_sense) {
-		int rc;
+		enum scsi_disposition rc;
 
 		rc = sdev->handler->check_sense(sdev, &sshdr);
 		if (rc != SCSI_RETURN_NOT_HANDLED)
@@ -723,7 +723,7 @@ static void scsi_handle_queue_full(struct scsi_device *sdev)
  *    don't allow for the possibility of retries here, and we are a lot
  *    more restrictive about what we consider acceptable.
  */
-static int scsi_eh_completed_normally(struct scsi_cmnd *scmd)
+static enum scsi_disposition scsi_eh_completed_normally(struct scsi_cmnd *scmd)
 {
 	/*
 	 * first check the host byte, to see if there is anything in there
@@ -804,10 +804,10 @@ static void scsi_eh_done(struct scsi_cmnd *scmd)
  * scsi_try_host_reset - ask host adapter to reset itself
  * @scmd:	SCSI cmd to send host reset.
  */
-static int scsi_try_host_reset(struct scsi_cmnd *scmd)
+static enum scsi_disposition scsi_try_host_reset(struct scsi_cmnd *scmd)
 {
 	unsigned long flags;
-	int rtn;
+	enum scsi_disposition rtn;
 	struct Scsi_Host *host = scmd->device->host;
 	struct scsi_host_template *hostt = host->hostt;
 
@@ -834,10 +834,10 @@ static int scsi_try_host_reset(struct scsi_cmnd *scmd)
  * scsi_try_bus_reset - ask host to perform a bus reset
  * @scmd:	SCSI cmd to send bus reset.
  */
-static int scsi_try_bus_reset(struct scsi_cmnd *scmd)
+static enum scsi_disposition scsi_try_bus_reset(struct scsi_cmnd *scmd)
 {
 	unsigned long flags;
-	int rtn;
+	enum scsi_disposition rtn;
 	struct Scsi_Host *host = scmd->device->host;
 	struct scsi_host_template *hostt = host->hostt;
 
@@ -876,10 +876,10 @@ static void __scsi_report_device_reset(struct scsi_device *sdev, void *data)
  *    timer on it, and set the host back to a consistent state prior to
  *    returning.
  */
-static int scsi_try_target_reset(struct scsi_cmnd *scmd)
+static enum scsi_disposition scsi_try_target_reset(struct scsi_cmnd *scmd)
 {
 	unsigned long flags;
-	int rtn;
+	enum scsi_disposition rtn;
 	struct Scsi_Host *host = scmd->device->host;
 	struct scsi_host_template *hostt = host->hostt;
 
@@ -907,9 +907,9 @@ static int scsi_try_target_reset(struct scsi_cmnd *scmd)
  *    timer on it, and set the host back to a consistent state prior to
  *    returning.
  */
-static int scsi_try_bus_device_reset(struct scsi_cmnd *scmd)
+static enum scsi_disposition scsi_try_bus_device_reset(struct scsi_cmnd *scmd)
 {
-	int rtn;
+	enum scsi_disposition rtn;
 	struct scsi_host_template *hostt = scmd->device->host->hostt;
 
 	if (!hostt->eh_device_reset_handler)
@@ -938,8 +938,8 @@ static int scsi_try_bus_device_reset(struct scsi_cmnd *scmd)
  *    if the device is temporarily unavailable (eg due to a
  *    link down on FibreChannel)
  */
-static int scsi_try_to_abort_cmd(struct scsi_host_template *hostt,
-				 struct scsi_cmnd *scmd)
+static enum scsi_disposition
+scsi_try_to_abort_cmd(struct scsi_host_template *hostt, struct scsi_cmnd *scmd)
 {
 	if (!hostt->eh_abort_handler)
 		return FAILED;
@@ -1072,8 +1072,8 @@ EXPORT_SYMBOL(scsi_eh_restore_cmnd);
  * Return value:
  *    SUCCESS or FAILED or NEEDS_RETRY
  */
-static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd, unsigned char *cmnd,
-			     int cmnd_size, int timeout, unsigned sense_bytes)
+static enum scsi_disposition scsi_send_eh_cmnd(struct scsi_cmnd *scmd,
+	unsigned char *cmnd, int cmnd_size, int timeout, unsigned sense_bytes)
 {
 	struct scsi_device *sdev = scmd->device;
 	struct Scsi_Host *shost = sdev->host;
@@ -1180,12 +1180,13 @@ retry:
  *    that we obtain it on our own. This function will *not* return until
  *    the command either times out, or it completes.
  */
-static int scsi_request_sense(struct scsi_cmnd *scmd)
+static enum scsi_disposition scsi_request_sense(struct scsi_cmnd *scmd)
 {
 	return scsi_send_eh_cmnd(scmd, NULL, 0, scmd->device->eh_timeout, ~0);
 }
 
-static int scsi_eh_action(struct scsi_cmnd *scmd, int rtn)
+static enum scsi_disposition
+scsi_eh_action(struct scsi_cmnd *scmd, enum scsi_disposition rtn)
 {
 	if (!blk_rq_is_passthrough(scmd->request)) {
 		struct scsi_driver *sdrv = scsi_cmd_to_driver(scmd);
@@ -1238,7 +1239,7 @@ int scsi_eh_get_sense(struct list_head *work_q,
 {
 	struct scsi_cmnd *scmd, *next;
 	struct Scsi_Host *shost;
-	int rtn;
+	enum scsi_disposition rtn;
 
 	/*
 	 * If SCSI_EH_ABORT_SCHEDULED has been set, it is timeout IO,
@@ -1316,7 +1317,8 @@ EXPORT_SYMBOL_GPL(scsi_eh_get_sense);
 static int scsi_eh_tur(struct scsi_cmnd *scmd)
 {
 	static unsigned char tur_command[6] = {TEST_UNIT_READY, 0, 0, 0, 0, 0};
-	int retry_cnt = 1, rtn;
+	int retry_cnt = 1;
+	enum scsi_disposition rtn;
 
 retry_tur:
 	rtn = scsi_send_eh_cmnd(scmd, tur_command, 6,
@@ -1404,7 +1406,8 @@ static int scsi_eh_try_stu(struct scsi_cmnd *scmd)
 	static unsigned char stu_command[6] = {START_STOP, 0, 0, 0, 1, 0};
 
 	if (scmd->device->allow_restart) {
-		int i, rtn = NEEDS_RETRY;
+		int i;
+		enum scsi_disposition rtn = NEEDS_RETRY;
 
 		for (i = 0; rtn == NEEDS_RETRY && i < 2; i++)
 			rtn = scsi_send_eh_cmnd(scmd, stu_command, 6, scmd->device->request_queue->rq_timeout, 0);
@@ -1498,7 +1501,7 @@ static int scsi_eh_bus_device_reset(struct Scsi_Host *shost,
 {
 	struct scsi_cmnd *scmd, *bdr_scmd, *next;
 	struct scsi_device *sdev;
-	int rtn;
+	enum scsi_disposition rtn;
 
 	shost_for_each_device(sdev, shost) {
 		if (scsi_host_eh_past_deadline(shost)) {
@@ -1565,7 +1568,7 @@ static int scsi_eh_target_reset(struct Scsi_Host *shost,
 
 	while (!list_empty(&tmp_list)) {
 		struct scsi_cmnd *next, *scmd;
-		int rtn;
+		enum scsi_disposition rtn;
 		unsigned int id;
 
 		if (scsi_host_eh_past_deadline(shost)) {
@@ -1623,7 +1626,7 @@ static int scsi_eh_bus_reset(struct Scsi_Host *shost,
 	struct scsi_cmnd *scmd, *chan_scmd, *next;
 	LIST_HEAD(check_list);
 	unsigned int channel;
-	int rtn;
+	enum scsi_disposition rtn;
 
 	/*
 	 * we really want to loop over the various channels, and do this on
@@ -1694,7 +1697,7 @@ static int scsi_eh_host_reset(struct Scsi_Host *shost,
 {
 	struct scsi_cmnd *scmd, *next;
 	LIST_HEAD(check_list);
-	int rtn;
+	enum scsi_disposition rtn;
 
 	if (!list_empty(work_q)) {
 		scmd = list_entry(work_q->next,
@@ -1800,9 +1803,9 @@ check_type:
  *    doesn't require the error handler read (i.e. we don't need to
  *    abort/reset), this function should return SUCCESS.
  */
-int scsi_decide_disposition(struct scsi_cmnd *scmd)
+enum scsi_disposition scsi_decide_disposition(struct scsi_cmnd *scmd)
 {
-	int rtn;
+	enum scsi_disposition rtn;
 
 	/*
 	 * if the device is offline, then we clearly just pass the result back
@@ -2365,7 +2368,8 @@ scsi_ioctl_reset(struct scsi_device *dev, int __user *arg)
 	struct Scsi_Host *shost = dev->host;
 	struct request *rq;
 	unsigned long flags;
-	int error = 0, rtn, val;
+	int error = 0, val;
+	enum scsi_disposition rtn;
 
 	if (!capable(CAP_SYS_ADMIN) || !capable(CAP_SYS_RAWIO))
 		return -EACCES;
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 8ffb789de6f7..d7c0d5a5f263 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1441,7 +1441,7 @@ static bool scsi_mq_lld_busy(struct request_queue *q)
 static void scsi_complete(struct request *rq)
 {
 	struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);
-	int disposition;
+	enum scsi_disposition disposition;
 
 	INIT_LIST_HEAD(&cmd->eh_entry);
 
diff --git a/drivers/scsi/scsi_priv.h b/drivers/scsi/scsi_priv.h
index ed240f006c04..75d6f23e4fff 100644
--- a/drivers/scsi/scsi_priv.h
+++ b/drivers/scsi/scsi_priv.h
@@ -74,7 +74,7 @@ extern void scsi_exit_devinfo(void);
 extern void scmd_eh_abort_handler(struct work_struct *work);
 extern enum blk_eh_timer_return scsi_times_out(struct request *req);
 extern int scsi_error_handler(void *host);
-extern int scsi_decide_disposition(struct scsi_cmnd *cmd);
+extern enum scsi_disposition scsi_decide_disposition(struct scsi_cmnd *cmd);
 extern void scsi_eh_wakeup(struct Scsi_Host *shost);
 extern void scsi_eh_scmd_add(struct scsi_cmnd *);
 void scsi_eh_ready_devs(struct Scsi_Host *shost,