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Wed, 17 Jan 2024 09:17:19 -0800 (PST) Received: from smtpclient.apple ([2402:d0c0:11:86::1]) by smtp.gmail.com with ESMTPSA id jw10-20020a056a00928a00b006d9af59eecesm1685787pfb.20.2024.01.17.09.17.17 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 17 Jan 2024 09:17:19 -0800 (PST) Content-Type: text/plain; charset=utf-8 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3774.300.61.1.2\)) Subject: Re: [PATCH] afs: Fix missing/incorrect unlocking of RCU read lock From: Alan Huang In-Reply-To: <2929034.1705508082@warthog.procyon.org.uk> Date: Thu, 18 Jan 2024 01:15:02 +0800 Cc: Marc Dionne , linux-afs@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Message-Id: References: <2929034.1705508082@warthog.procyon.org.uk> To: David Howells X-Mailer: Apple Mail (2.3774.300.61.1.2) > 2024=E5=B9=B41=E6=9C=8818=E6=97=A5 00:14=EF=BC=8CDavid Howells = =E5=86=99=E9=81=93=EF=BC=9A >=20 > In afs_proc_addr_prefs_show(), we need to unlock the RCU read lock in = both > places before returning (and not lock it again). >=20 > Fixes: f94f70d39cc2 ("afs: Provide a way to configure address = priorities") > Reported-by: Marc Dionne > Signed-off-by: David Howells > cc: linux-afs@lists.infradead.org > cc: linux-fsdevel@vger.kernel.org > --- > fs/afs/proc.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) >=20 > diff --git a/fs/afs/proc.c b/fs/afs/proc.c > index 3bd02571f30d..15eab053af6d 100644 > --- a/fs/afs/proc.c > +++ b/fs/afs/proc.c > @@ -166,7 +166,7 @@ static int afs_proc_addr_prefs_show(struct = seq_file *m, void *v) >=20 > if (!preflist) { > seq_puts(m, "NO PREFS\n"); > - return 0; > + goto out; > } >=20 > seq_printf(m, "PROT SUBNET PRIOR = (v=3D%u n=3D%u/%u/%u)\n", > @@ -191,7 +191,8 @@ static int afs_proc_addr_prefs_show(struct = seq_file *m, void *v) > } > } >=20 > - rcu_read_lock(); > +out: > + rcu_read_unlock(); What about using: guard(rcu)(); Thanks, Alan > return 0; > } >=20 >=20