From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757135AbdKGKk2 (ORCPT ); Tue, 7 Nov 2017 05:40:28 -0500 Received: from mout.kundenserver.de ([217.72.192.73]:51067 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757119AbdKGKkX (ORCPT ); Tue, 7 Nov 2017 05:40:23 -0500 From: Arnd Bergmann To: Valentina Manea , Shuah Khan , Greg Kroah-Hartman Cc: Arnd Bergmann , Krzysztof Opasiak , Johan Hovold , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 1/2] usbip: fix off-by-one frame number calculation Date: Tue, 7 Nov 2017 11:39:56 +0100 Message-Id: <20171107104010.2884193-1-arnd@arndb.de> X-Mailer: git-send-email 2.9.0 X-Provags-ID: V03:K0:TxQacLp55x7jhRYC8cT/3bd4g/andhnLCNOrNuqw2hxsecqWCwH dRtBRsALJlAJIrXirEsHqm3hAQ57uHAUeXwQJR+UCKX1TTSLpnfhx1QNtlJW+dzgD3ZOMck v1vyRuowsFaCCqacFdlyJGe6WUd5PhX1kaFN7yt2F+rMdQ0dpafTLVANfNerXI0D1OmNJIE E3aE3ni/viiQuySnmifIA== X-UI-Out-Filterresults: notjunk:1;V01:K0:OiNH6YCWpWU=:1upv3CwE2wpkjufpyrjja2 2IE5nzjJjUS3oBPsVXi7eoC154K5bjaYTM9VY5ZfzVg/fp+eMNCbSoUMHNwG0qrpXv0BDNE6W vmiNIiwoq99+yImYZzRsdGttEYE5mYAc44IGU+1vCH5k3Mn5KlO5wq1VskVCtPwKz0puK0Suf Fl4oa0u1ILPWQmjYNgsO8r2kRs4xQklpHb07UxxCxQn2Ik1wwIStlVz0QoZRZleJkzZXvjpvm CTxwMvbMar/UkzrlRyaQMqKf7VjJagUujqjczdhaxyl9pwIkVr4JzLo0kUFXkp3G7gUSwSGy0 uSB/EGxxwvvwOGFc0paDM2fJ6+jWjLJryTx40u+swTyE2Ng57QNxLdV3pdHGHTwXPTjTG38UU pSQ9c9oqLw97xR161q7tWUzvt6nsDBs4/pBkovBX8A0uWIIJVczHa8uTp/rqlHIC3hGNVzXhX wnk8Zz8bKUEsdOBBPcmE/mzaW8VNNV4ZSp1zCcoLxZii8f0ddDhDVUnZptcrG9a8DVvFj/m2A sT0MNg1dj4ICglCVWXe2fEIjxnc0OTxGOanN+Mh7OusSWxJvpc9uWE6H08ISfBk1y1dIIRwyv pisbpqyKh97SQRsp+H5poxYhMsDEMwTFwq3kNXl7wCr22OCaYTgyHI/qqm+IaNEoU2m8K5qaK SJaPkC2/Zw2Jf+1Im/isdIe+OgcOSwZXjUwjJ/OBarWnyJeAbXThva57JM4JJ0T7DPsXHo/5M /H1luS1Dnp6H1VhsEhU1q8IRsLf1bJatwyjCPQ== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org vgadget_get_frame returns a frame number from 0 to 2046, which may require an expensive division operation to wrap at one lower than the usual number. I can't see any reason for this, and all other drivers wrap at a power-of-two number. My best explanation is that it was a simple typo, so I'm changing the % modulo operator into a cheaper bitmask that the other drivers use, to make it wrap after 0x7ff rather than before it. Signed-off-by: Arnd Bergmann --- drivers/usb/usbip/vudc_dev.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/usb/usbip/vudc_dev.c b/drivers/usb/usbip/vudc_dev.c index 0c07348820ea..16fb4f85a6f6 100644 --- a/drivers/usb/usbip/vudc_dev.c +++ b/drivers/usb/usbip/vudc_dev.c @@ -145,7 +145,7 @@ static int vgadget_get_frame(struct usb_gadget *_gadget) do_gettimeofday(&now); return ((now.tv_sec - udc->start_time.tv_sec) * 1000 + (now.tv_usec - udc->start_time.tv_usec) / 1000) - % 0x7FF; + & 0x7FF; } static int vgadget_set_selfpowered(struct usb_gadget *_gadget, int value) -- 2.9.0