From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1031272AbeBNVOD (ORCPT ); Wed, 14 Feb 2018 16:14:03 -0500 Received: from mout.kundenserver.de ([217.72.192.73]:33679 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030501AbeBNVOC (ORCPT ); Wed, 14 Feb 2018 16:14:02 -0500 To: "linux-kernel@vger.kernel.org" From: Enrico Weigelt Subject: fs_struct refcounting: spinlock vs atomic Organization: metux IT consult Message-ID: <7547a9ed-a2e7-e975-a3ba-f41abc16f4bc@metux.net> Date: Wed, 14 Feb 2018 22:13:59 +0100 User-Agent: Mozilla/5.0 (X11; Linux i686 on x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.0 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Provags-ID: V03:K0:SFcOOyf2m5mnay7ZnIl0O1T4Cz1st7yvgRIng163wvoOeJigK3U qcbRyy6r1oa6TGN6iDTdnKPFpF8RNWUg6UtfmIIWkD7snPsH0O2BeaXs7qgJAFB89bD3RVp 904hMJ4PKQzOfiSumhWxoAb+SgedCncdR805r+GcMNbwJiPEwj1LZnrn6oanzaavp8x8w4a CF9vV2rvSF2PfZ0rBcadw== X-UI-Out-Filterresults: notjunk:1;V01:K0:ffClgBCp7B0=:jeDUyEFKtqjQQSffP7OuLh iQvGEeyBDHyzATvKEZNrB88HXJEvA+II1I3aFLo6pu7T0HOG1CWJV297igvJYMg1GqMJMlJBn DZ1iBV7IHMef0nVyTHYUp6W1x2wUiv9VidHJ/E3ET8T2MGLZT/otoTGtE8rT2ssBrqpb0rmtx wfERO2zFNpq7QW2+jYwU1/1tQetIy9D4yg+LiibLvLySYn5h84opRpaZcuFDTEUPt9FWX9h6F a5lR/jA6X2MeMCDnafuJBDQY9gT0AjrheB+n7Tz2jdVm5co5g4/vxzRkdBQnK6uM3dpFjB/b5 SAV1vn2InuzTWmeXjjAIErtiuxRpC+H8IwR/M1d0Er62MRSx1fQ6aVCoSAYDvApu5hzVWwxTJ yroGlzsC1Uo6wgk7839rRC1aUCoRxXZc9xYj3fCIn9ZJiYruAaZbHqoGTJmVoJIIW6sJGe02D BJjpxfJdVfbYodXkwx7F2lOt9k2bvHu20Td4wbxpX2dVDUQzYRiRJlN5+pthN6Vl/MwFWZczQ FPx1PqZjKQZtkRnunrEa0g4N6kz94XQtN/sKjaoNsqIUZNeVC4Wir5j4cw8WX3e+1KZCbThZm XzN1fgijxT/6sf3q0MukU8+BcRqKbP+c1qsQS2b1m78ihZX06jgRzHZwb8ldZB7u5z6AQFtfS J0xV9qPy93nvitHUJi3uyS3QRWTOD4kTJIEoGhpwG9HRsowa7QTDGBbOCpxaacAWQHoNIyXEB UaZBQ9HKxWD2Uy1CHr01L3xIlfl6oGtSppYXF2t8ZzyG3PdvIvUbPXKrAvQ= Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi folks, in fork.c, a spinlock is held for fs_struct refcounting, while other places - eg. switch_task_namespaces uses atomic_dec_and_test() on the nsproxy. What's the exact difference here ? Could the atomic counting also used for fs_struct ? --mtx -- Enrico Weigelt, metux IT consult Free software and Linux embedded engineering info@metux.net -- +49-151-27565287