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([2600:4040:5c62:8200::feb]) by smtp.gmail.com with ESMTPSA id b34-20020a05620a272200b007435a646354sm4932800qkp.0.2023.04.19.13.54.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 19 Apr 2023 13:54:31 -0700 (PDT) Message-ID: Subject: Re: [PATCH v2] drm: use mgr->dev in drm_dbg_kms in drm_dp_add_payload_part2 From: Lyude Paul To: Jeff Layton , David Airlie , Daniel Vetter Cc: Wayne.Lin@amd.com, alexdeucher@gmail.com, Jani Nikula , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Date: Wed, 19 Apr 2023 16:54:31 -0400 In-Reply-To: <20230419112447.18471-1-jlayton@kernel.org> References: <20230419112447.18471-1-jlayton@kernel.org> Organization: Red Hat Inc. Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.44.4 (3.44.4-2.fc36) MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Reviewed-by: Lyude Paul Thanks! On Wed, 2023-04-19 at 07:24 -0400, Jeff Layton wrote: > I've been experiencing some intermittent crashes down in the display > driver code. The symptoms are ususally a line like this in dmesg: >=20 > amdgpu 0000:30:00.0: [drm] Failed to create MST payload for port 0000= 00006d3a3885: -5 >=20 > ...followed by an Oops due to a NULL pointer dereference. >=20 > Switch to using mgr->dev instead of state->dev since "state" can be > NULL in some cases. >=20 > Link: https://bugzilla.redhat.com/show_bug.cgi?id=3D2184855 > Suggested-by: Jani Nikula > Signed-off-by: Jeff Layton > --- > drivers/gpu/drm/display/drm_dp_mst_topology.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) >=20 > I've been running this patch for a couple of days, but the problem > hasn't occurred again as of yet. It seems sane though as long as we can > assume that mgr->dev will be valid even when "state" is a NULL pointer. >=20 > diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/= drm/display/drm_dp_mst_topology.c > index 38dab76ae69e..e2e21ce79510 100644 > --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c > +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c > @@ -3404,7 +3404,7 @@ int drm_dp_add_payload_part2(struct drm_dp_mst_topo= logy_mgr *mgr, > =20 > /* Skip failed payloads */ > if (payload->vc_start_slot =3D=3D -1) { > - drm_dbg_kms(state->dev, "Part 1 of payload creation for %s failed, ski= pping part 2\n", > + drm_dbg_kms(mgr->dev, "Part 1 of payload creation for %s failed, skipp= ing part 2\n", > payload->port->connector->name); > return -EIO; > } --=20 Cheers, Lyude Paul (she/her) Software Engineer at Red Hat