USB: fix usbmon and DMA mapping for scatter-gather URBs

This patch (as1368) fixes a rather obscure bug in usbmon: When tracing
URBs sent by the scatter-gather library, it accesses the data buffers
while they are still mapped for DMA.

The solution is to move the mapping and unmapping out of the s-g
library and into the usual place in hcd.c.  This requires the addition
of new URB flag bits to describe the kind of mapping needed, since we
have to call dma_map_sg() if the HCD supports native scatter-gather
operation and dma_map_page() if it doesn't.  The nice thing about
having the new flags is that they simplify the testing for unmapping.

The patch removes the only caller of usb_buffer_[un]map_sg(), so those
functions are #if'ed out.  A later patch will remove them entirely.

As a result of this change, urb->sg will be set in situations where
it wasn't set previously.  Hence the xhci and whci drivers are
adjusted to test urb->num_sgs instead, which retains its original
meaning and is nonzero only when the HCD has to handle a scatterlist.

Finally, even when a submission error occurs we don't want to hand
URBs to usbmon before they are unmapped.  The submission path is
rearranged so that map_urb_for_dma() is called only for non-root-hub
URBs and unmap_urb_for_dma() is called immediately after a submission
error.  This simplifies the error handling.

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

4 files changed, 125 insertions, 102 deletions

diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
index 38d4700926f7..6a05e6934455 100644
--- a/drivers/usb/core/hcd.c
+++ b/drivers/usb/core/hcd.c
@@ -1259,6 +1259,51 @@ static void hcd_free_coherent(struct usb_bus *bus, dma_addr_t *dma_handle,
         *dma_handle = 0;
 }
 
+static void unmap_urb_for_dma(struct usb_hcd *hcd, struct urb *urb)
+{
+        enum dma_data_direction dir;
+
+        if (urb->transfer_flags & URB_SETUP_MAP_SINGLE)
+                dma_unmap_single(hcd->self.controller,
+                                urb->setup_dma,
+                                sizeof(struct usb_ctrlrequest),
+                                DMA_TO_DEVICE);
+        else if (urb->transfer_flags & URB_SETUP_MAP_LOCAL)
+                hcd_free_coherent(urb->dev->bus,
+                                &urb->setup_dma,
+                                (void **) &urb->setup_packet,
+                                sizeof(struct usb_ctrlrequest),
+                                DMA_TO_DEVICE);
+
+        dir = usb_urb_dir_in(urb) ? DMA_FROM_DEVICE : DMA_TO_DEVICE;
+        if (urb->transfer_flags & URB_DMA_MAP_SG)
+                dma_unmap_sg(hcd->self.controller,
+                                urb->sg->sg,
+                                urb->num_sgs,
+                                dir);
+        else if (urb->transfer_flags & URB_DMA_MAP_PAGE)
+                dma_unmap_page(hcd->self.controller,
+                                urb->transfer_dma,
+                                urb->transfer_buffer_length,
+                                dir);
+        else if (urb->transfer_flags & URB_DMA_MAP_SINGLE)
+                dma_unmap_single(hcd->self.controller,
+                                urb->transfer_dma,
+                                urb->transfer_buffer_length,
+                                dir);
+        else if (urb->transfer_flags & URB_MAP_LOCAL)
+                hcd_free_coherent(urb->dev->bus,
+                                &urb->transfer_dma,
+                                &urb->transfer_buffer,
+                                urb->transfer_buffer_length,
+                                dir);
+
+        /* Make it safe to call this routine more than once */
+        urb->transfer_flags &= ~(URB_SETUP_MAP_SINGLE | URB_SETUP_MAP_LOCAL |
+                        URB_DMA_MAP_SG | URB_DMA_MAP_PAGE |
+                        URB_DMA_MAP_SINGLE | URB_MAP_LOCAL);
+}
+
 static int map_urb_for_dma(struct usb_hcd *hcd, struct urb *urb,
                            gfp_t mem_flags)
 {
@@ -1270,8 +1315,6 @@ static int map_urb_for_dma(struct usb_hcd *hcd, struct urb *urb,
          * unless it uses pio or talks to another transport,
          * or uses the provided scatter gather list for bulk.
          */
-        if (is_root_hub(urb->dev))
-                return 0;
 
         if (usb_endpoint_xfer_control(&urb->ep->desc)
             && !(urb->transfer_flags & URB_NO_SETUP_DMA_MAP)) {
@@ -1284,6 +1327,7 @@ static int map_urb_for_dma(struct usb_hcd *hcd, struct urb *urb,
                         if (dma_mapping_error(hcd->self.controller,
                                                 urb->setup_dma))
                                 return -EAGAIN;
+                        urb->transfer_flags |= URB_SETUP_MAP_SINGLE;
                 } else if (hcd->driver->flags & HCD_LOCAL_MEM)
                         ret = hcd_alloc_coherent(
                                         urb->dev->bus, mem_flags,
@@ -1291,20 +1335,57 @@ static int map_urb_for_dma(struct usb_hcd *hcd, struct urb *urb,
                                         (void **)&urb->setup_packet,
                                         sizeof(struct usb_ctrlrequest),
                                         DMA_TO_DEVICE);
+                        if (ret)
+                                return ret;
+                        urb->transfer_flags |= URB_SETUP_MAP_LOCAL;
         }
 
         dir = usb_urb_dir_in(urb) ? DMA_FROM_DEVICE : DMA_TO_DEVICE;
-        if (ret == 0 && urb->transfer_buffer_length != 0
+        if (urb->transfer_buffer_length != 0
             && !(urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP)) {
                 if (hcd->self.uses_dma) {
-                        urb->transfer_dma = dma_map_single (
-                                        hcd->self.controller,
-                                        urb->transfer_buffer,
-                                        urb->transfer_buffer_length,
-                                        dir);
-                        if (dma_mapping_error(hcd->self.controller,
+                        if (urb->num_sgs) {
+                                int n = dma_map_sg(
+                                                hcd->self.controller,
+                                                urb->sg->sg,
+                                                urb->num_sgs,
+                                                dir);
+                                if (n <= 0)
+                                        ret = -EAGAIN;
+                                else
+                                        urb->transfer_flags |= URB_DMA_MAP_SG;
+                                if (n != urb->num_sgs) {
+                                        urb->num_sgs = n;
+                                        urb->transfer_flags |=
+                                                        URB_DMA_SG_COMBINED;
+                                }
+                        } else if (urb->sg) {
+                                struct scatterlist *sg;
+
+                                sg = (struct scatterlist *) urb->sg;
+                                urb->transfer_dma = dma_map_page(
+                                                hcd->self.controller,
+                                                sg_page(sg),
+                                                sg->offset,
+                                                urb->transfer_buffer_length,
+                                                dir);
+                                if (dma_mapping_error(hcd->self.controller,
                                                 urb->transfer_dma))
-                                return -EAGAIN;
+                                        ret = -EAGAIN;
+                                else
+                                        urb->transfer_flags |= URB_DMA_MAP_PAGE;
+                        } else {
+                                urb->transfer_dma = dma_map_single(
+                                                hcd->self.controller,
+                                                urb->transfer_buffer,
+                                                urb->transfer_buffer_length,
+                                                dir);
+                                if (dma_mapping_error(hcd->self.controller,
+                                                urb->transfer_dma))
+                                        ret = -EAGAIN;
+                                else
+                                        urb->transfer_flags |= URB_DMA_MAP_SINGLE;
+                        }
                 } else if (hcd->driver->flags & HCD_LOCAL_MEM) {
                         ret = hcd_alloc_coherent(
                                         urb->dev->bus, mem_flags,
@@ -1312,55 +1393,16 @@ static int map_urb_for_dma(struct usb_hcd *hcd, struct urb *urb,
                                         &urb->transfer_buffer,
                                         urb->transfer_buffer_length,
                                         dir);
-
-                        if (ret && usb_endpoint_xfer_control(&urb->ep->desc)
-                            && !(urb->transfer_flags & URB_NO_SETUP_DMA_MAP))
-                                hcd_free_coherent(urb->dev->bus,
-                                        &urb->setup_dma,
-                                        (void **)&urb->setup_packet,
-                                        sizeof(struct usb_ctrlrequest),
-                                        DMA_TO_DEVICE);
+                        if (ret == 0)
+                                urb->transfer_flags |= URB_MAP_LOCAL;
                 }
+                if (ret && (urb->transfer_flags & (URB_SETUP_MAP_SINGLE |
+                                URB_SETUP_MAP_LOCAL)))
+                        unmap_urb_for_dma(hcd, urb);
         }
         return ret;
 }
 
-static void unmap_urb_for_dma(struct usb_hcd *hcd, struct urb *urb)
-{
-        enum dma_data_direction dir;
-
-        if (is_root_hub(urb->dev))
-                return;
-
-        if (usb_endpoint_xfer_control(&urb->ep->desc)
-            && !(urb->transfer_flags & URB_NO_SETUP_DMA_MAP)) {
-                if (hcd->self.uses_dma)
-                        dma_unmap_single(hcd->self.controller, urb->setup_dma,
-                                        sizeof(struct usb_ctrlrequest),
-                                        DMA_TO_DEVICE);
-                else if (hcd->driver->flags & HCD_LOCAL_MEM)
-                        hcd_free_coherent(urb->dev->bus, &urb->setup_dma,
-                                        (void **)&urb->setup_packet,
-                                        sizeof(struct usb_ctrlrequest),
-                                        DMA_TO_DEVICE);
-        }
-
-        dir = usb_urb_dir_in(urb) ? DMA_FROM_DEVICE : DMA_TO_DEVICE;
-        if (urb->transfer_buffer_length != 0
-            && !(urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP)) {
-                if (hcd->self.uses_dma)
-                        dma_unmap_single(hcd->self.controller,
-                                        urb->transfer_dma,
-                                        urb->transfer_buffer_length,
-                                        dir);
-                else if (hcd->driver->flags & HCD_LOCAL_MEM)
-                        hcd_free_coherent(urb->dev->bus, &urb->transfer_dma,
-                                        &urb->transfer_buffer,
-                                        urb->transfer_buffer_length,
-                                        dir);
-        }
-}
-
 /*-------------------------------------------------------------------------*/
 
 /* may be called in any context with a valid urb->dev usecount
@@ -1389,21 +1431,20 @@ int usb_hcd_submit_urb (struct urb *urb, gfp_t mem_flags)
          * URBs must be submitted in process context with interrupts
          * enabled.
          */
-        status = map_urb_for_dma(hcd, urb, mem_flags);
-        if (unlikely(status)) {
-                usbmon_urb_submit_error(&hcd->self, urb, status);
-                goto error;
-        }
 
-        if (is_root_hub(urb->dev))
+        if (is_root_hub(urb->dev)) {
                 status = rh_urb_enqueue(hcd, urb);
-        else
-                status = hcd->driver->urb_enqueue(hcd, urb, mem_flags);
+        } else {
+                status = map_urb_for_dma(hcd, urb, mem_flags);
+                if (likely(status == 0)) {
+                        status = hcd->driver->urb_enqueue(hcd, urb, mem_flags);
+                        if (unlikely(status))
+                                unmap_urb_for_dma(hcd, urb);
+                }
+        }
 
         if (unlikely(status)) {
                 usbmon_urb_submit_error(&hcd->self, urb, status);
-                unmap_urb_for_dma(hcd, urb);
- error:
                 urb->hcpriv = NULL;
                 INIT_LIST_HEAD(&urb->urb_list);
                 atomic_dec(&urb->use_count);
diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c
index 619c44fb8a96..79d1cdf4a635 100644
--- a/drivers/usb/core/message.c
+++ b/drivers/usb/core/message.c
@@ -259,9 +259,6 @@ static void sg_clean(struct usb_sg_request *io)
                 kfree(io->urbs);
                 io->urbs = NULL;
         }
-        if (io->dev->dev.dma_mask != NULL)
-                usb_buffer_unmap_sg(io->dev, usb_pipein(io->pipe),
-                                    io->sg, io->nents);
         io->dev = NULL;
 }
 
@@ -364,7 +361,6 @@ int usb_sg_init(struct usb_sg_request *io, struct usb_device *dev,
 {
         int i;
         int urb_flags;
-        int dma;
         int use_sg;
 
         if (!io || !dev || !sg
@@ -378,21 +374,9 @@ int usb_sg_init(struct usb_sg_request *io, struct usb_device *dev,
         io->pipe = pipe;
         io->sg = sg;
         io->nents = nents;
-
-        /* not all host controllers use DMA (like the mainstream pci ones);
-         * they can use PIO (sl811) or be software over another transport.
-         */
-        dma = (dev->dev.dma_mask != NULL);
-        if (dma)
-                io->entries = usb_buffer_map_sg(dev, usb_pipein(pipe),
-                                                sg, nents);
-        else
-                io->entries = nents;
+        io->entries = nents;
 
         /* initialize all the urbs we'll use */
-        if (io->entries <= 0)
-                return io->entries;
-
         if (dev->bus->sg_tablesize > 0) {
                 io->urbs = kmalloc(sizeof *io->urbs, mem_flags);
                 use_sg = true;
@@ -404,8 +388,6 @@ int usb_sg_init(struct usb_sg_request *io, struct usb_device *dev,
                 goto nomem;
 
         urb_flags = 0;
-        if (dma)
-                urb_flags |= URB_NO_TRANSFER_DMA_MAP;
         if (usb_pipein(pipe))
                 urb_flags |= URB_SHORT_NOT_OK;
 
@@ -423,12 +405,13 @@ int usb_sg_init(struct usb_sg_request *io, struct usb_device *dev,
 
                 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_dma_len(sg);
+                                        sg->length;
                         }
                 }
                 io->urbs[0]->sg = io;
@@ -454,26 +437,16 @@ int usb_sg_init(struct usb_sg_request *io, struct usb_device *dev,
                         io->urbs[i]->context = io;
 
                         /*
-                         * Some systems need to revert to PIO when DMA is temporarily
-                         * unavailable.  For their sakes, both transfer_buffer and
-                         * transfer_dma are set when possible.
-                         *
-                         * Note that if IOMMU coalescing occurred, we cannot
-                         * trust sg_page anymore, so check if S/G list shrunk.
+                         * Some systems can't use DMA; they use PIO instead.
+                         * For their sakes, transfer_buffer is set whenever
+                         * possible.
                          */
-                        if (io->nents == io->entries && !PageHighMem(sg_page(sg)))
+                        if (!PageHighMem(sg_page(sg)))
                                 io->urbs[i]->transfer_buffer = sg_virt(sg);
                         else
                                 io->urbs[i]->transfer_buffer = NULL;
 
-                        if (dma) {
-                                io->urbs[i]->transfer_dma = sg_dma_address(sg);
-                                len = sg_dma_len(sg);
-                        } else {
-                                /* hc may use _only_ transfer_buffer */
-                                len = sg->length;
-                        }
-
+                        len = sg->length;
                         if (length) {
                                 len = min_t(unsigned, len, length);
                                 length -= len;
@@ -481,6 +454,8 @@ int usb_sg_init(struct usb_sg_request *io, struct usb_device *dev,
                                         io->entries = i + 1;
                         }
                         io->urbs[i]->transfer_buffer_length = len;
+
+                        io->urbs[i]->sg = (struct usb_sg_request *) sg;
                 }
                 io->urbs[--i]->transfer_flags &= ~URB_NO_INTERRUPT;
         }
diff --git a/drivers/usb/core/urb.c b/drivers/usb/core/urb.c
index 2532a0917f8c..a760e46871c5 100644
--- a/drivers/usb/core/urb.c
+++ b/drivers/usb/core/urb.c
@@ -333,9 +333,12 @@ int usb_submit_urb(struct urb *urb, gfp_t mem_flags)
                 is_out = usb_endpoint_dir_out(&ep->desc);
         }
 
-        /* Cache the direction for later use */
-        urb->transfer_flags = (urb->transfer_flags & ~URB_DIR_MASK) |
-                        (is_out ? URB_DIR_OUT : URB_DIR_IN);
+        /* Clear the internal flags and cache the direction for later use */
+        urb->transfer_flags &= ~(URB_DIR_MASK | URB_DMA_MAP_SINGLE |
+                        URB_DMA_MAP_PAGE | URB_DMA_MAP_SG | URB_MAP_LOCAL |
+                        URB_SETUP_MAP_SINGLE | URB_SETUP_MAP_LOCAL |
+                        URB_DMA_SG_COMBINED);
+        urb->transfer_flags |= (is_out ? URB_DIR_OUT : URB_DIR_IN);
 
         if (xfertype != USB_ENDPOINT_XFER_CONTROL &&
                         dev->state < USB_STATE_CONFIGURED)
diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c
index 097172e2ba06..8180ce533ebf 100644
--- a/drivers/usb/core/usb.c
+++ b/drivers/usb/core/usb.c
@@ -881,6 +881,7 @@ void usb_buffer_unmap(struct urb *urb)
 EXPORT_SYMBOL_GPL(usb_buffer_unmap);
 #endif  /*  0  */
 
+#if 0
 /**
  * usb_buffer_map_sg - create scatterlist DMA mapping(s) for an endpoint
  * @dev: device to which the scatterlist will be mapped
@@ -924,6 +925,7 @@ int usb_buffer_map_sg(const struct usb_device *dev, int is_in,
                         is_in ? DMA_FROM_DEVICE : DMA_TO_DEVICE) ? : -ENOMEM;
 }
 EXPORT_SYMBOL_GPL(usb_buffer_map_sg);
+#endif
 
 /* XXX DISABLED, no users currently.  If you wish to re-enable this
  * XXX please determine whether the sync is to transfer ownership of
@@ -960,6 +962,7 @@ void usb_buffer_dmasync_sg(const struct usb_device *dev, int is_in,
 EXPORT_SYMBOL_GPL(usb_buffer_dmasync_sg);
 #endif
 
+#if 0
 /**
  * usb_buffer_unmap_sg - free DMA mapping(s) for a scatterlist
  * @dev: device to which the scatterlist will be mapped
@@ -985,6 +988,7 @@ void usb_buffer_unmap_sg(const struct usb_device *dev, int is_in,
                         is_in ? DMA_FROM_DEVICE : DMA_TO_DEVICE);
 }
 EXPORT_SYMBOL_GPL(usb_buffer_unmap_sg);
+#endif
 
 /* To disable USB, kernel command line is 'nousb' not 'usbcore.nousb' */
 #ifdef MODULE