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authorKrzysztof Opasiak <k.opasiak@samsung.com>2016-12-20 21:52:16 +0300
committerFelipe Balbi <felipe.balbi@linux.intel.com>2017-01-02 11:55:28 +0300
commit7e4da3fcf7c9fe042f2f7cb7bf23861a899b4a8f (patch)
treed29bc543131edce31c5ac39040feee02000eea3d /drivers/usb/gadget/composite.c
parent51c1685d956221576e165dd88a20063b169bae5a (diff)
downloadlinux-7e4da3fcf7c9fe042f2f7cb7bf23861a899b4a8f.tar.xz
usb: gadget: composite: Test get_alt() presence instead of set_alt()
By convention (according to doc) if function does not provide get_alt() callback composite framework should assume that it has only altsetting 0 and should respond with error if host tries to set other one. After commit dd4dff8b035f ("USB: composite: Fix bug: should test set_alt function pointer before use it") we started checking set_alt() callback instead of get_alt(). This check is useless as we check if set_alt() is set inside usb_add_function() and fail if it's NULL. Let's fix this check and move comment about why we check the get method instead of set a little bit closer to prevent future false fixes. Fixes: dd4dff8b035f ("USB: composite: Fix bug: should test set_alt function pointer before use it") Cc: stable <stable@vger.kernel.org> Signed-off-by: Krzysztof Opasiak <k.opasiak@samsung.com> Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Diffstat (limited to 'drivers/usb/gadget/composite.c')
-rw-r--r--drivers/usb/gadget/composite.c12
1 files changed, 8 insertions, 4 deletions
diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
index 41ab61f9b6e0..002822d98fda 100644
--- a/drivers/usb/gadget/composite.c
+++ b/drivers/usb/gadget/composite.c
@@ -1694,9 +1694,7 @@ composite_setup(struct usb_gadget *gadget, const struct usb_ctrlrequest *ctrl)
value = min(w_length, (u16) 1);
break;
- /* function drivers must handle get/set altsetting; if there's
- * no get() method, we know only altsetting zero works.
- */
+ /* function drivers must handle get/set altsetting */
case USB_REQ_SET_INTERFACE:
if (ctrl->bRequestType != USB_RECIP_INTERFACE)
goto unknown;
@@ -1705,7 +1703,13 @@ composite_setup(struct usb_gadget *gadget, const struct usb_ctrlrequest *ctrl)
f = cdev->config->interface[intf];
if (!f)
break;
- if (w_value && !f->set_alt)
+
+ /*
+ * If there's no get_alt() method, we know only altsetting zero
+ * works. There is no need to check if set_alt() is not NULL
+ * as we check this in usb_add_function().
+ */
+ if (w_value && !f->get_alt)
break;
value = f->set_alt(f, w_index, w_value);
if (value == USB_GADGET_DELAYED_STATUS) {