block: mtip32xx: Fix usage of dma_map_sg()

The dma_map_sg() can fail and, in case of failure, returns 0.  If it
fails, mtip_hw_submit_io() returns an error.

The dma_unmap_sg() requires the nents parameter to be the same as the
one passed to dma_map_sg(). This patch saves the nents in
command->scatter_ents.

Fixes: 88523a61558a ("block: Add driver for Micron RealSSD pcie flash cards")
Signed-off-by: Thomas Fourier <fourier.thomas@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20250627121123.203731-2-fourier.thomas@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/block/mtip32xx/mtip32xx.c b/drivers/block/mtip32xx/mtip32xx.c
index 66ce6b81c7d938388aedf9b5fa69c6d10741e9ea..8fc7761397bd7a78435605a1d1b8ef0d4eb18205 100644 (file)
--- a/drivers/block/mtip32xx/mtip32xx.c
+++ b/drivers/block/mtip32xx/mtip32xx.c
@@ -2040,11 +2040,12 @@ static int mtip_hw_ioctl(struct driver_data *dd, unsigned int cmd,
  * @dir      Direction (read or write)
  *
  * return value
- *     None
+ *     0       The IO completed successfully.
+ *     -ENOMEM The DMA mapping failed.
  */
-static void mtip_hw_submit_io(struct driver_data *dd, struct request *rq,
-                             struct mtip_cmd *command,
-                             struct blk_mq_hw_ctx *hctx)
+static int mtip_hw_submit_io(struct driver_data *dd, struct request *rq,
+                            struct mtip_cmd *command,
+                            struct blk_mq_hw_ctx *hctx)
 {
        struct mtip_cmd_hdr *hdr =
                dd->port->command_list + sizeof(struct mtip_cmd_hdr) * rq->tag;
@@ -2056,12 +2057,14 @@ static void mtip_hw_submit_io(struct driver_data *dd, struct request *rq,
        unsigned int nents;
 
        /* Map the scatter list for DMA access */
-       nents = blk_rq_map_sg(rq, command->sg);
-       nents = dma_map_sg(&dd->pdev->dev, command->sg, nents, dma_dir);
+       command->scatter_ents = blk_rq_map_sg(rq, command->sg);
+       nents = dma_map_sg(&dd->pdev->dev, command->sg,
+                          command->scatter_ents, dma_dir);
+       if (!nents)
+               return -ENOMEM;
 
-       prefetch(&port->flags);
 
-       command->scatter_ents = nents;
+       prefetch(&port->flags);
 
        /*
         * The number of retries for this command before it is
@@ -2112,11 +2115,13 @@ static void mtip_hw_submit_io(struct driver_data *dd, struct request *rq,
        if (unlikely(port->flags & MTIP_PF_PAUSE_IO)) {
                set_bit(rq->tag, port->cmds_to_issue);
                set_bit(MTIP_PF_ISSUE_CMDS_BIT, &port->flags);
-               return;
+               return 0;
        }
 
        /* Issue the command to the hardware */
        mtip_issue_ncq_command(port, rq->tag);
+
+       return 0;
 }
 
 /*
@@ -3315,7 +3320,9 @@ static blk_status_t mtip_queue_rq(struct blk_mq_hw_ctx *hctx,
 
        blk_mq_start_request(rq);
 
-       mtip_hw_submit_io(dd, rq, cmd, hctx);
+       if (mtip_hw_submit_io(dd, rq, cmd, hctx))
+               return BLK_STS_IOERR;
+
        return BLK_STS_OK;
 }