scsi: target: tcmu: Factor out new helper ring_insert_padding

The new helper ring_insert_padding is split off from and then called by
queue_cmd_ring. It inserts a padding if necessary.  The new helper will in
a subsequent patch be used during writing of TMR notifications to command
ring.

Link: https://lore.kernel.org/r/20200726153510.13077-6-bstroesser@ts.fujitsu.com
Reviewed-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Bodo Stroesser <bstroesser@ts.fujitsu.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/target/target_core_user.c b/drivers/target/target_core_user.c
index 25c480f..eb68c5f 100644 (file)
--- a/drivers/target/target_core_user.c
+++ b/drivers/target/target_core_user.c
@@ -926,6 +926,34 @@ static int add_to_qfull_queue(struct tcmu_cmd *tcmu_cmd)
        return 0;
 }
 
+static uint32_t ring_insert_padding(struct tcmu_dev *udev, size_t cmd_size)
+{
+       struct tcmu_cmd_entry_hdr *hdr;
+       struct tcmu_mailbox *mb = udev->mb_addr;
+       uint32_t cmd_head = mb->cmd_head % udev->cmdr_size; /* UAM */
+
+       /* Insert a PAD if end-of-ring space is too small */
+       if (head_to_end(cmd_head, udev->cmdr_size) < cmd_size) {
+               size_t pad_size = head_to_end(cmd_head, udev->cmdr_size);
+
+               hdr = (void *) mb + CMDR_OFF + cmd_head;
+               tcmu_hdr_set_op(&hdr->len_op, TCMU_OP_PAD);
+               tcmu_hdr_set_len(&hdr->len_op, pad_size);
+               hdr->cmd_id = 0; /* not used for PAD */
+               hdr->kflags = 0;
+               hdr->uflags = 0;
+               tcmu_flush_dcache_range(hdr, sizeof(*hdr));
+
+               UPDATE_HEAD(mb->cmd_head, pad_size, udev->cmdr_size);
+               tcmu_flush_dcache_range(mb, sizeof(*mb));
+
+               cmd_head = mb->cmd_head % udev->cmdr_size; /* UAM */
+               WARN_ON(cmd_head != 0);
+       }
+
+       return cmd_head;
+}
+
 /**
  * queue_cmd_ring - queue cmd to ring or internally
  * @tcmu_cmd: cmd to queue
@@ -941,7 +969,7 @@ static int queue_cmd_ring(struct tcmu_cmd *tcmu_cmd, sense_reason_t *scsi_err)
        struct tcmu_dev *udev = tcmu_cmd->tcmu_dev;
        struct se_cmd *se_cmd = tcmu_cmd->se_cmd;
        size_t base_command_size, command_size;
-       struct tcmu_mailbox *mb;
+       struct tcmu_mailbox *mb = udev->mb_addr;
        struct tcmu_cmd_entry *entry;
        struct iovec *iov;
        int iov_cnt, cmd_id;
@@ -980,8 +1008,6 @@ static int queue_cmd_ring(struct tcmu_cmd *tcmu_cmd, sense_reason_t *scsi_err)
        if (!list_empty(&udev->qfull_queue))
                goto queue;
 
-       mb = udev->mb_addr;
-       cmd_head = mb->cmd_head % udev->cmdr_size; /* UAM */
        if ((command_size > (udev->cmdr_size / 2)) ||
            data_length > udev->data_size) {
                pr_warn("TCMU: Request of size %zu/%zu is too big for %u/%zu "
@@ -1001,24 +1027,7 @@ static int queue_cmd_ring(struct tcmu_cmd *tcmu_cmd, sense_reason_t *scsi_err)
                goto queue;
        }
 
-       /* Insert a PAD if end-of-ring space is too small */
-       if (head_to_end(cmd_head, udev->cmdr_size) < command_size) {
-               size_t pad_size = head_to_end(cmd_head, udev->cmdr_size);
-
-               entry = (void *) mb + CMDR_OFF + cmd_head;
-               tcmu_hdr_set_op(&entry->hdr.len_op, TCMU_OP_PAD);
-               tcmu_hdr_set_len(&entry->hdr.len_op, pad_size);
-               entry->hdr.cmd_id = 0; /* not used for PAD */
-               entry->hdr.kflags = 0;
-               entry->hdr.uflags = 0;
-               tcmu_flush_dcache_range(entry, sizeof(entry->hdr));
-
-               UPDATE_HEAD(mb->cmd_head, pad_size, udev->cmdr_size);
-               tcmu_flush_dcache_range(mb, sizeof(*mb));
-
-               cmd_head = mb->cmd_head % udev->cmdr_size; /* UAM */
-               WARN_ON(cmd_head != 0);
-       }
+       cmd_head = ring_insert_padding(udev, command_size);
 
        entry = (void *) mb + CMDR_OFF + cmd_head;
        memset(entry, 0, command_size);