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authorMing Lei <ming.lei@redhat.com>2019-06-18 04:37:48 +0300
committerMartin K. Petersen <martin.petersen@oracle.com>2019-06-20 22:21:32 +0300
commit1194b5ce57d27c2ad49ed26f8cec98757c7c23ec (patch)
treece74be24a12b0c7139534ba271df8cfcb6767be3 /drivers/usb/image
parent74eb7446eda5e348dbb90981e91e9caf54f2fde4 (diff)
downloadlinux-1194b5ce57d27c2ad49ed26f8cec98757c7c23ec.tar.xz
scsi: usb: image: microtek: use sg helper to iterate over scatterlist
Unlike the legacy I/O path, scsi-mq preallocates a large array to hold the scatterlist for each request. This static allocation can consume substantial amounts of memory on modern controllers which support a large number of concurrently outstanding requests. To facilitate a switch to a smaller static allocation combined with a dynamic allocation for requests that need it, we need to make sure all SCSI drivers handle chained scatterlists correctly. Convert remaining drivers that directly dereference the scatterlist array to using the iterator functions. [mkp: clarified commit message] Cc: Oliver Neukum <oliver@neukum.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: linux-usb@vger.kernel.org Reviewed-by: Bart Van Assche <bvanassche@acm.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Diffstat (limited to 'drivers/usb/image')
-rw-r--r--drivers/usb/image/microtek.c20
-rw-r--r--drivers/usb/image/microtek.h2
2 files changed, 9 insertions, 13 deletions
diff --git a/drivers/usb/image/microtek.c b/drivers/usb/image/microtek.c
index 607be1f4fe27..0a57c2cc8e5a 100644
--- a/drivers/usb/image/microtek.c
+++ b/drivers/usb/image/microtek.c
@@ -488,7 +488,6 @@ static void mts_command_done( struct urb *transfer )
static void mts_do_sg (struct urb* transfer)
{
- struct scatterlist * sg;
int status = transfer->status;
MTS_INT_INIT();
@@ -500,13 +499,12 @@ static void mts_do_sg (struct urb* transfer)
mts_transfer_cleanup(transfer);
}
- sg = scsi_sglist(context->srb);
- context->fragment++;
+ context->curr_sg = sg_next(context->curr_sg);
mts_int_submit_urb(transfer,
context->data_pipe,
- sg_virt(&sg[context->fragment]),
- sg[context->fragment].length,
- context->fragment + 1 == scsi_sg_count(context->srb) ?
+ sg_virt(context->curr_sg),
+ context->curr_sg->length,
+ sg_is_last(context->curr_sg) ?
mts_data_done : mts_do_sg);
}
@@ -526,22 +524,20 @@ static void
mts_build_transfer_context(struct scsi_cmnd *srb, struct mts_desc* desc)
{
int pipe;
- struct scatterlist * sg;
-
+
MTS_DEBUG_GOT_HERE();
desc->context.instance = desc;
desc->context.srb = srb;
- desc->context.fragment = 0;
if (!scsi_bufflen(srb)) {
desc->context.data = NULL;
desc->context.data_length = 0;
return;
} else {
- sg = scsi_sglist(srb);
- desc->context.data = sg_virt(&sg[0]);
- desc->context.data_length = sg[0].length;
+ desc->context.curr_sg = scsi_sglist(srb);
+ desc->context.data = sg_virt(desc->context.curr_sg);
+ desc->context.data_length = desc->context.curr_sg->length;
}
diff --git a/drivers/usb/image/microtek.h b/drivers/usb/image/microtek.h
index 66685e59241a..7bd5f4639c4a 100644
--- a/drivers/usb/image/microtek.h
+++ b/drivers/usb/image/microtek.h
@@ -21,7 +21,7 @@ struct mts_transfer_context
void *data;
unsigned data_length;
int data_pipe;
- int fragment;
+ struct scatterlist *curr_sg;
u8 *scsi_status; /* status returned from ep_response after command completion */
};