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b=ZWeZiCKu+oIq14ANWhg9axIzcW14nW7oj/PYT+3BfRAGqbsCwMlfTrl+CGtMDhZrQ tXLV1TsYQALqmjgL5A0/3fYM5BRZOXZi9j7ReRC0s2HpoxszhmDFvl4+8ldreI27CM 6ia3Rtcw3CxN1hDJJYIIjf3Au2tq1XrN8aXaVc4c= Date: Thu, 7 May 2026 17:06:57 +0300 From: Laurent Pinchart To: Luca Ceresoli Cc: Andrzej Hajda , Neil Armstrong , Robert Foss , Jonas Karlman , Jernej Skrabec , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Rob Clark , Dmitry Baryshkov , Abhinav Kumar , Jessica Zhang , Sean Paul , Marijn Suijten , Sumit Semwal , John Stultz , Tomi Valkeinen , Michal Simek , Hui Pu , Ian Ray , Thomas Petazzoni , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, freedreno@lists.freedesktop.org, linux-arm-kernel@lists.infradead.org, Dmitry Baryshkov Subject: Re: [PATCH v5 01/11] drm/bridge: drm_bridge_put(): ignore ERR_PTR Message-ID: <20260507140657.GK1938994@killaraus.ideasonboard.com> References: <20260507-drm-bridge-alloc-getput-panel_or_bridge-v5-0-472b913b5cb7@bootlin.com> <20260507-drm-bridge-alloc-getput-panel_or_bridge-v5-1-472b913b5cb7@bootlin.com> Precedence: bulk X-Mailing-List: linux-arm-msm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20260507-drm-bridge-alloc-getput-panel_or_bridge-v5-1-472b913b5cb7@bootlin.com> On Thu, May 07, 2026 at 03:45:19PM +0200, Luca Ceresoli wrote: > Most functions returning a struct drm_bridge pointer currently return a > valid pointer or NULL, but this restricts their ability to return an error > code as an ERR_PTR describing the error kind. > > In preparation to have new APIs that can return a struct drm_bridge pointer > holding an ERR_PTR (and for those which already do) make drm_bridge_put() > ignore ERR_PTR values, just like it ignores NULL pointers. > > This will avoid annoying error checking in many places and the risk of > missing error checks. > > Suggested-by: Laurent Pinchart > Link: https://lore.kernel.org/all/20260318152533.GA633439@killaraus.ideasonboard.com/ > Suggested-by: Dmitry Baryshkov > Link: https://lore.kernel.org/all/omlnswxukeqgnatzdvooaashgkfcacjevkvbkm6xt33itgua2k@jcmzll2w6kdq/ > Reviewed-by: Dmitry Baryshkov > Signed-off-by: Luca Ceresoli Reviewed-by: Laurent Pinchart > --- > > Changes in v5: > - don't change drm_bridge_get(), only drm_bridge_put() has known use cases > > Changes in v4: > - removed incorrect change to drm_bridge_clear_and_put() kdoc > > Patch added in v2 > --- > drivers/gpu/drm/drm_bridge.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c > index d4b3478258ec..4aaea517b436 100644 > --- a/drivers/gpu/drm/drm_bridge.c > +++ b/drivers/gpu/drm/drm_bridge.c > @@ -300,7 +300,7 @@ EXPORT_SYMBOL(drm_bridge_get); > > /** > * drm_bridge_put - Release a bridge reference > - * @bridge: DRM bridge; if NULL this function does nothing > + * @bridge: DRM bridge; if NULL or an ERR_PTR this function does nothing > * > * This function decrements the bridge's reference count and frees the > * object if the reference count drops to zero. > @@ -310,7 +310,7 @@ EXPORT_SYMBOL(drm_bridge_get); > */ > void drm_bridge_put(struct drm_bridge *bridge) > { > - if (bridge) > + if (!IS_ERR_OR_NULL(bridge)) > kref_put(&bridge->refcount, __drm_bridge_free); > } > EXPORT_SYMBOL(drm_bridge_put); > -- Regards, Laurent Pinchart