USB: simplify usb_sg_init()

This patch (as1377) simplifies the code in usb_sg_init(), without
changing its functionality.  It also removes a couple of unused fields
from the usb_sg_request structure.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

2 files changed, 38 insertions, 57 deletions

diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c
index 63919b8abee..a73e08fdab3 100644
--- a/drivers/usb/core/message.c
+++ b/drivers/usb/core/message.c
@@ -371,79 +371,64 @@ int usb_sg_init(struct usb_sg_request *io, struct usb_device *dev,
         spin_lock_init(&io->lock);
         io->dev = dev;
         io->pipe = pipe;
-        io->sg = sg;
-        io->nents = nents;
-        io->entries = nents;
 
-        /* initialize all the urbs we'll use */
         if (dev->bus->sg_tablesize > 0) {
-                io->urbs = kmalloc(sizeof *io->urbs, mem_flags);
                 use_sg = true;
+                io->entries = 1;
         } else {
-                io->urbs = kmalloc(io->entries * sizeof *io->urbs, mem_flags);
                 use_sg = false;
+                io->entries = nents;
         }
+
+        /* initialize all the urbs we'll use */
+        io->urbs = kmalloc(io->entries * sizeof *io->urbs, mem_flags);
         if (!io->urbs)
                 goto nomem;
 
-        urb_flags = 0;
+        urb_flags = URB_NO_INTERRUPT;
         if (usb_pipein(pipe))
                 urb_flags |= URB_SHORT_NOT_OK;
 
-        if (use_sg) {
-                io->urbs[0] = usb_alloc_urb(0, mem_flags);
-                if (!io->urbs[0]) {
-                        io->entries = 0;
-                        goto nomem;
-                }
-
-                io->urbs[0]->dev = NULL;
-                io->urbs[0]->pipe = pipe;
-                io->urbs[0]->interval = period;
-                io->urbs[0]->transfer_flags = urb_flags;
+        for_each_sg(sg, sg, io->entries, i) {
+                struct urb *urb;
+                unsigned len;
 
-                io->urbs[0]->complete = sg_complete;
-                io->urbs[0]->context = io;
-
-                /* A length of zero means transfer the whole sg list */
-                io->urbs[0]->transfer_buffer_length = length;
-                if (length == 0) {
-                        for_each_sg(sg, sg, io->entries, i) {
-                                io->urbs[0]->transfer_buffer_length +=
-                                        sg->length;
-                        }
+                urb = usb_alloc_urb(0, mem_flags);
+                if (!urb) {
+                        io->entries = i;
+                        goto nomem;
                 }
-                io->urbs[0]->sg = sg;
-                io->urbs[0]->num_sgs = io->entries;
-                io->entries = 1;
-        } else {
-                urb_flags |= URB_NO_INTERRUPT;
-                for_each_sg(sg, sg, io->entries, i) {
-                        unsigned len;
-
-                        io->urbs[i] = usb_alloc_urb(0, mem_flags);
-                        if (!io->urbs[i]) {
-                                io->entries = i;
-                                goto nomem;
+                io->urbs[i] = urb;
+
+                urb->dev = NULL;
+                urb->pipe = pipe;
+                urb->interval = period;
+                urb->transfer_flags = urb_flags;
+                urb->complete = sg_complete;
+                urb->context = io;
+                urb->sg = sg;
+
+                if (use_sg) {
+                        /* There is no single transfer buffer */
+                        urb->transfer_buffer = NULL;
+                        urb->num_sgs = nents;
+
+                        /* A length of zero means transfer the whole sg list */
+                        len = length;
+                        if (len == 0) {
+                                for_each_sg(sg, sg, nents, i)
+                                        len += sg->length;
                         }
-
-                        io->urbs[i]->dev = NULL;
-                        io->urbs[i]->pipe = pipe;
-                        io->urbs[i]->interval = period;
-                        io->urbs[i]->transfer_flags = urb_flags;
-
-                        io->urbs[i]->complete = sg_complete;
-                        io->urbs[i]->context = io;
-
+                } else {
                         /*
                          * Some systems can't use DMA; they use PIO instead.
                          * For their sakes, transfer_buffer is set whenever
                          * possible.
                          */
                         if (!PageHighMem(sg_page(sg)))
-                                io->urbs[i]->transfer_buffer = sg_virt(sg);
+                                urb->transfer_buffer = sg_virt(sg);
                         else
-                                io->urbs[i]->transfer_buffer = NULL;
+                                urb->transfer_buffer = NULL;
 
                         len = sg->length;
                         if (length) {
@@ -452,12 +437,10 @@ int usb_sg_init(struct usb_sg_request *io, struct usb_device *dev,
                                 if (length == 0)
                                         io->entries = i + 1;
                         }
-                        io->urbs[i]->transfer_buffer_length = len;
-
-                        io->urbs[i]->sg = sg;
                 }
-                io->urbs[--i]->transfer_flags &= ~URB_NO_INTERRUPT;
+                urb->transfer_buffer_length = len;
         }
+        io->urbs[--i]->transfer_flags &= ~URB_NO_INTERRUPT;
 
         /* transaction state */
         io->count = io->entries;
diff --git a/include/linux/usb.h b/include/linux/usb.h
index eec9e74f332..ce07062ebc2 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -1469,8 +1469,6 @@ struct usb_sg_request {
 
         struct usb_device       *dev;
         int                     pipe;
-        struct scatterlist      *sg;
-        int                     nents;
 
         int                     entries;
         struct urb              **urbs;