lk/linux-kernel-test
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

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

Browse Source 
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>
This commit is contained in:
Alan Stern
2010-04-02 13:27:28 -04:00
committed by Greg Kroah-Hartman
parent 0ff8d1b3c8
commit ff9c895f07
9 changed files with 139 additions and 109 deletions
Download Patch File Download Diff File Expand all files Collapse all files

45
drivers/usb/core/message.c
View File

@@ -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;
}