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Fri, 29 Jan 2021 21:29:44 +0000 (GMT) References: <20210128181421.2279-1-hch@lst.de> <20210128181421.2279-5-hch@lst.de> <874kj023bj.fsf@manicouagan.localdomain> <20210129051012.GA2053@lst.de> User-agent: mu4e 1.4.10; emacs 27.1 From: Thiago Jung Bauermann To: Christoph Hellwig Cc: Frederic Barrat , Andrew Donnellan , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Daniel Vetter , Jessica Yu , Josh Poimboeuf , Jiri Kosina , Miroslav Benes , Petr Mladek , Joe Lawrence , Michal Marek , linux-kbuild@vger.kernel.org, Masahiro Yamada , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, live-patching@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Subject: Re: [PATCH 04/13] module: use RCU to synchronize find_module In-reply-to: <20210129051012.GA2053@lst.de> Date: Fri, 29 Jan 2021 18:29:43 -0300 Message-ID: <871re31lfc.fsf@manicouagan.localdomain> MIME-Version: 1.0 Content-Type: text/plain X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.369,18.0.737 definitions=2021-01-29_09:2021-01-29,2021-01-29 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 spamscore=0 lowpriorityscore=0 adultscore=0 clxscore=1015 phishscore=0 suspectscore=0 impostorscore=0 mlxlogscore=999 mlxscore=0 malwarescore=0 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2101290100 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Christoph Hellwig writes: > On Thu, Jan 28, 2021 at 05:50:56PM -0300, Thiago Jung Bauermann wrote: >> > struct module *find_module(const char *name) >> > { >> > - module_assert_mutex(); >> >> Does it make sense to replace the assert above with the warn below (untested)? >> >> RCU_LOCKDEP_WARN(rcu_read_lock_sched_held()); > > One caller actually holds module_mutex still. And find_module_all, > which implements the actual logic already asserts that either > module_mutex is held or rcu_read_lock, so I don't tink we need an > extra one here. Ok, thanks for the clarification. -- Thiago Jung Bauermann IBM Linux Technology Center