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Wed, 03 Jun 2020 01:24:12 -0700 (PDT) Date: Wed, 3 Jun 2020 10:24:11 +0200 From: Daniel Vetter To: Jeykumar Sankaran Subject: Re: [PATCH] drm/connector: notify userspace on hotplug after register complete Message-ID: <20200603082411.GI20149@phenom.ffwll.local> Mail-Followup-To: Jeykumar Sankaran , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Steve Cohen , seanpaul@chromium.org References: <1591155451-10393-1-git-send-email-jsanka@codeaurora.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1591155451-10393-1-git-send-email-jsanka@codeaurora.org> X-Operating-System: Linux phenom 5.6.0-1-amd64 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200603_012415_396897_FC4BC6A2 X-CRM114-Status: GOOD ( 17.99 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-arm-kernel@lists.infradead.org, seanpaul@chromium.org, Steve Cohen , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Jun 02, 2020 at 08:37:31PM -0700, Jeykumar Sankaran wrote: > drm connector notifies userspace on hotplug event prematurely before > late_register and mode_object register completes. This leads to a race > between userspace and kernel on updating the IDR list. So, move the > notification to end of connector register. > > Signed-off-by: Jeykumar Sankaran > Signed-off-by: Steve Cohen Hm on the unregister side we don't have the race, there we remove everything and then send out the uevent. But there the uevent is also generated in a separate step, so I wonder whether we shouldn't do the same for register for symmetry ... Anyway this looks good, nice catch, I'll add cc: stable and merge. -Daniel > --- > drivers/gpu/drm/drm_connector.c | 5 +++++ > drivers/gpu/drm/drm_sysfs.c | 3 --- > 2 files changed, 5 insertions(+), 3 deletions(-) > > diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c > index b1099e1..d877ddc 100644 > --- a/drivers/gpu/drm/drm_connector.c > +++ b/drivers/gpu/drm/drm_connector.c > @@ -27,6 +27,7 @@ > #include > #include > #include > +#include > > #include > > @@ -523,6 +524,10 @@ int drm_connector_register(struct drm_connector *connector) > drm_mode_object_register(connector->dev, &connector->base); > > connector->registration_state = DRM_CONNECTOR_REGISTERED; > + > + /* Let userspace know we have a new connector */ > + drm_sysfs_hotplug_event(connector->dev); > + > goto unlock; > > err_debugfs: > diff --git a/drivers/gpu/drm/drm_sysfs.c b/drivers/gpu/drm/drm_sysfs.c > index 939f003..f0336c8 100644 > --- a/drivers/gpu/drm/drm_sysfs.c > +++ b/drivers/gpu/drm/drm_sysfs.c > @@ -291,9 +291,6 @@ int drm_sysfs_connector_add(struct drm_connector *connector) > return PTR_ERR(connector->kdev); > } > > - /* Let userspace know we have a new connector */ > - drm_sysfs_hotplug_event(dev); > - > if (connector->ddc) > return sysfs_create_link(&connector->kdev->kobj, > &connector->ddc->dev.kobj, "ddc"); > -- > The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, > a Linux Foundation Collaborative Project > > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel