From 7e4da3fcf7c9fe042f2f7cb7bf23861a899b4a8f Mon Sep 17 00:00:00 2001 From: Krzysztof Opasiak Date: Tue, 20 Dec 2016 19:52:16 +0100 Subject: [PATCH] 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 Signed-off-by: Krzysztof Opasiak Signed-off-by: Felipe Balbi --- drivers/usb/gadget/composite.c | 12 ++++++++---- 1 file 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) { -- 2.20.1