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Wed, 06 Aug 2025 05:45:25 -0700 (PDT) X-Google-Smtp-Source: AGHT+IHTMYU08BgHnXR1+czy5QcVCMHzz8YG+OtEkdxRx4oxsXU/v8COQ+2pdCxkJHBTMz4Q6mU6DQ== X-Received: by 2002:a05:622a:355:b0:4b0:8f6e:d728 with SMTP id d75a77b69052e-4b09138c9c0mr38195381cf.21.1754484325386; Wed, 06 Aug 2025 05:45:25 -0700 (PDT) Received: from gmonaco-thinkpadt14gen3.rmtit.csb ([185.107.56.35]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-4b085ad7d08sm19326441cf.53.2025.08.06.05.45.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 06 Aug 2025 05:45:25 -0700 (PDT) Message-ID: <8f379f2072ee12afda37455aa0ad4e37d53c4f2d.camel@redhat.com> Subject: Re: [PATCH] rv: Fix wrong type cast in enabled_monitors_next() From: Gabriele Monaco To: Nam Cao Cc: Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , linux-trace-kernel@vger.kernel.org, linux-kernel@vger.kernel.org Date: Wed, 06 Aug 2025 14:45:22 +0200 In-Reply-To: <20250806120911.989365-1-namcao@linutronix.de> References: <20250806120911.989365-1-namcao@linutronix.de> Autocrypt: addr=gmonaco@redhat.com; prefer-encrypt=mutual; keydata=mDMEZuK5YxYJKwYBBAHaRw8BAQdAmJ3dM9Sz6/Hodu33Qrf8QH2bNeNbOikqYtxWFLVm0 1a0JEdhYnJpZWxlIE1vbmFjbyA8Z21vbmFjb0ByZWRoYXQuY29tPoiZBBMWCgBBFiEEysoR+AuB3R Zwp6j270psSVh4TfIFAmbiuWMCGwMFCQWjmoAFCwkIBwICIgIGFQoJCAsCBBYCAwECHgcCF4AACgk Q70psSVh4TfJzZgD/TXjnqCyqaZH/Y2w+YVbvm93WX2eqBqiVZ6VEjTuGNs8A/iPrKbzdWC7AicnK xyhmqeUWOzFx5P43S1E1dhsrLWgP Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.56.2 (3.56.2-1.fc42) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Wed, 2025-08-06 at 14:09 +0200, Nam Cao wrote: > Argument 'p' of enabled_monitors_next() is not a pointer to struct > rv_monitor, it is actually a pointer to the list_head inside struct > rv_monitor. Therefore it is wrong to cast 'p' to struct rv_monitor *. >=20 > This wrong type cast has been there since the beginning. But it still > worked because the list_head was the first field in struct > rv_monitor_def. > This is no longer true since commit 24cbfe18d55a ("rv: Merge struct > rv_monitor_def into struct rv_monitor") moved the list_head, and this > wrong type cast became a functional problem. >=20 > Properly use container_of() instead. Good catch, thanks! Reviewed-by: Gabriele Monaco >=20 > Fixes: 24cbfe18d55a ("rv: Merge struct rv_monitor_def into struct > rv_monitor") > Signed-off-by: Nam Cao > --- > =C2=A0kernel/trace/rv/rv.c | 2 +- > =C2=A01 file changed, 1 insertion(+), 1 deletion(-) >=20 > diff --git a/kernel/trace/rv/rv.c b/kernel/trace/rv/rv.c > index bd7d56dbf6c2..6ce3495164d8 100644 > --- a/kernel/trace/rv/rv.c > +++ b/kernel/trace/rv/rv.c > @@ -495,7 +495,7 @@ static void *available_monitors_next(struct > seq_file *m, void *p, loff_t *pos) > =C2=A0 */ > =C2=A0static void *enabled_monitors_next(struct seq_file *m, void *p, > loff_t *pos) > =C2=A0{ > - struct rv_monitor *mon =3D p; > + struct rv_monitor *mon =3D container_of(p, struct rv_monitor, > list); > =C2=A0 > =C2=A0 (*pos)++; > =C2=A0