Commit f419a08f authored by Arnd Bergmann's avatar Arnd Bergmann Committed by Linus Torvalds
Browse files

drivers/memstick/host/r592.c: avoid gcc-6 warning

The r592 driver relies on behavior of the DMA mapping API that is
normally observed but not guaranteed by the API.  Instead it uses a
runtime check to fail transfers if the API ever behaves

When CONFIG_NEED_SG_DMA_LENGTH is not set, one of the checks turns into a
comparison of a variable with itself, which gcc-6.0 now warns about:

drivers/memstick/host/r592.c: In function 'r592_transfer_fifo_dma':
drivers/memstick/host/r592.c:302:31: error: self-comparison always evaluates to false [-Werror=tautological-compare]
    (sg_dma_len(&dev->req->sg) < dev->req->sg.length)) {

The check itself is not a problem, so this patch just rephrases the
condition in a way that gcc does not consider an indication of a mistake.
We already know that dev->req->sg.length was initially R592_LFIFO_SIZE, so
we can compare it to that constant again.

Signed-off-by: default avatarArnd Bergmann <>
Cc: Maxim Levitsky <>
Cc: Quentin Lambert <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent 102c2595
......@@ -298,8 +298,7 @@ static int r592_transfer_fifo_dma(struct r592_device *dev)
sg_count = dma_map_sg(&dev->pci_dev->dev, &dev->req->sg, 1, is_write ?
if (sg_count != 1 ||
(sg_dma_len(&dev->req->sg) < dev->req->sg.length)) {
if (sg_count != 1 || sg_dma_len(&dev->req->sg) < R592_LFIFO_SIZE) {
message("problem in dma_map_sg");
return -EIO;
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