[PATCH] scsi: resolve sg buffer const-ness issue

From: Dave Gordon
Date: Thu May 21 2015 - 07:06:27 EST


do_device_access() takes a separate parameter to indicate the direction
of data transfer, which it used to use to select the appropriate function
out of sg_pcopy_{to,from}_buffer(). However these two functions now have
different const-ness in their signatures, leading to compiler warnings.

So this patch makes it bypass these wrappers and call the underlying
function sg_copy_buffer() directly; this has the same calling style as
do_device_access() i.e. a separate direction-of-transfer parameter and
no pointers-to-const, so skipping the wrappers not only eliminates the
warning, it also make the code simpler :)

Signed-off-by: Dave Gordon <david.s.gordon@xxxxxxxxx>
---
drivers/scsi/scsi_debug.c | 12 ++++--------
1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
index 1f8e2dc..30268bb 100644
--- a/drivers/scsi/scsi_debug.c
+++ b/drivers/scsi/scsi_debug.c
@@ -2363,17 +2363,13 @@ do_device_access(struct scsi_cmnd *scmd, u64 lba, u32 num, bool do_write)
u64 block, rest = 0;
struct scsi_data_buffer *sdb;
enum dma_data_direction dir;
- size_t (*func)(struct scatterlist *, unsigned int, void *, size_t,
- off_t);

if (do_write) {
sdb = scsi_out(scmd);
dir = DMA_TO_DEVICE;
- func = sg_pcopy_to_buffer;
} else {
sdb = scsi_in(scmd);
dir = DMA_FROM_DEVICE;
- func = sg_pcopy_from_buffer;
}

if (!sdb->length)
@@ -2385,16 +2381,16 @@ do_device_access(struct scsi_cmnd *scmd, u64 lba, u32 num, bool do_write)
if (block + num > sdebug_store_sectors)
rest = block + num - sdebug_store_sectors;

- ret = func(sdb->table.sgl, sdb->table.nents,
+ ret = sg_copy_buffer(sdb->table.sgl, sdb->table.nents,
fake_storep + (block * scsi_debug_sector_size),
- (num - rest) * scsi_debug_sector_size, 0);
+ (num - rest) * scsi_debug_sector_size, 0, do_write);
if (ret != (num - rest) * scsi_debug_sector_size)
return ret;

if (rest) {
- ret += func(sdb->table.sgl, sdb->table.nents,
+ ret += sg_copy_buffer(sdb->table.sgl, sdb->table.nents,
fake_storep, rest * scsi_debug_sector_size,
- (num - rest) * scsi_debug_sector_size);
+ (num - rest) * scsi_debug_sector_size, do_write);
}

return ret;
--
1.7.9.5


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