Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752563AbdFHAKt (ORCPT ); Wed, 7 Jun 2017 20:10:49 -0400 Received: from wtarreau.pck.nerim.net ([62.212.114.60]:50149 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752039AbdFGXCO (ORCPT ); Wed, 7 Jun 2017 19:02:14 -0400 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, linux@roeck-us.net Cc: Krzysztof Opasiak , Felipe Balbi , Willy Tarreau Subject: [PATCH 3.10 038/250] usb: gadget: composite: Test get_alt() presence instead of set_alt() Date: Thu, 8 Jun 2017 00:57:04 +0200 Message-Id: <1496876436-32402-39-git-send-email-w@1wt.eu> X-Mailer: git-send-email 2.8.0.rc2.1.gbe9624a In-Reply-To: <1496876436-32402-1-git-send-email-w@1wt.eu> References: <1496876436-32402-1-git-send-email-w@1wt.eu> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2239 Lines: 59 From: Krzysztof Opasiak commit 7e4da3fcf7c9fe042f2f7cb7bf23861a899b4a8f upstream. 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") Signed-off-by: Krzysztof Opasiak Signed-off-by: Felipe Balbi Signed-off-by: Willy Tarreau --- 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 a660716..584e43c 100644 --- a/drivers/usb/gadget/composite.c +++ b/drivers/usb/gadget/composite.c @@ -1320,9 +1320,7 @@ 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; @@ -1331,7 +1329,13 @@ 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) { -- 2.8.0.rc2.1.gbe9624a