[PATCH 4.9 04/31] usb: gadget: core: unmap request from DMA only if previously mapped

Greg Kroah-Hartman
2019-11-15T06:22:40Z

From: Jack Pham <jackp@codeaurora.org>

commit 31fe084ffaaf8abece14f8ca28e5e3b4e2bf97b6 upstream.

In the SG case this is already handled since a non-zero
request->num_mapped_sgs is a clear indicator that dma_map_sg()
had been called. While it would be nice to do the same for the
singly mapped case by simply checking for non-zero request->dma,
it's conceivable that 0 is a valid dma_addr_t handle. Hence add
a flag 'dma_mapped' to struct usb_request and use this to
determine the need to call dma_unmap_single(). Otherwise, if a
request is not DMA mapped then the result of calling
usb_request_unmap_request() would safely be a no-op.

Signed-off-by: Jack Pham <jackp@codeaurora.org>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/usb/gadget/udc/core.c | 5 ++++-
include/linux/usb/gadget.h | 2 ++
2 files changed, 6 insertions(+), 1 deletion(-)

--- a/drivers/usb/gadget/udc/core.c
+++ b/drivers/usb/gadget/udc/core.c
@@ -817,6 +817,8 @@ int usb_gadget_map_request_by_dev(struct
dev_err(dev, "failed to map buffer\n");
return -EFAULT;
}
+
+ req->dma_mapped = 1;
}

return 0;
@@ -841,9 +843,10 @@ void usb_gadget_unmap_request_by_dev(str
is_in ? DMA_TO_DEVICE : DMA_FROM_DEVICE);

req->num_mapped_sgs = 0;
- } else {
+ } else if (req->dma_mapped) {
dma_unmap_single(dev, req->dma, req->length,
is_in ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
+ req->dma_mapped = 0;
}
}
EXPORT_SYMBOL_GPL(usb_gadget_unmap_request_by_dev);
--- a/include/linux/usb/gadget.h
+++ b/include/linux/usb/gadget.h
@@ -48,6 +48,7 @@ struct usb_ep;
* by adding a zero length packet as needed;
* @short_not_ok: When reading data, makes short packets be
* treated as errors (queue stops advancing till cleanup).
+ * @dma_mapped: Indicates if request has been mapped to DMA (internal)
* @complete: Function called when request completes, so this request and
* its buffer may be re-used. The function will always be called with
* interrupts disabled, and it must not sleep.
@@ -103,6 +104,7 @@ struct usb_request {
unsigned no_interrupt:1;
unsigned zero:1;
unsigned short_not_ok:1;
+ unsigned dma_mapped:1;

void (*complete)(struct usb_ep *ep,
struct usb_request *req);