{"id":3032,"url":"https://patchwork.libcamera.org/api/patches/3032/?format=json","web_url":"https://patchwork.libcamera.org/patch/3032/","project":{"id":1,"url":"https://patchwork.libcamera.org/api/projects/1/?format=json","name":"libcamera","link_name":"libcamera","list_id":"libcamera_core","list_email":"libcamera-devel@lists.libcamera.org","web_url":"","scm_url":"","webscm_url":""},"msgid":"<20200306202637.525587-27-nicolas@ndufresne.ca>","date":"2020-03-06T20:26:36","name":"[libcamera-devel,v3,26/27] gst: libcamerasrc: Prevent src task deadlock on exhausted buffer pool","commit_ref":null,"pull_url":null,"state":"accepted","archived":false,"hash":"fa6d5573afbe3bf349226413e0c2c26a189f14c7","submitter":{"id":30,"url":"https://patchwork.libcamera.org/api/people/30/?format=json","name":"Nicolas Dufresne","email":"nicolas@ndufresne.ca"},"delegate":null,"mbox":"https://patchwork.libcamera.org/patch/3032/mbox/","series":[{"id":705,"url":"https://patchwork.libcamera.org/api/series/705/?format=json","web_url":"https://patchwork.libcamera.org/project/libcamera/list/?series=705","date":"2020-03-06T20:26:10","name":"GStreamer Element for libcamera","version":3,"mbox":"https://patchwork.libcamera.org/series/705/mbox/"}],"comments":"https://patchwork.libcamera.org/api/patches/3032/comments/","check":"pending","checks":"https://patchwork.libcamera.org/api/patches/3032/checks/","tags":{},"headers":{"Return-Path":"","Received":["from bhuna.collabora.co.uk (bhuna.collabora.co.uk\n\t[IPv6:2a00:1098:0:82:1000:25:2eeb:e3e3])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 7F7E0628B3\n\tfor ;\n\tFri, 6 Mar 2020 21:27:13 +0100 (CET)","from nicolas-tpx395.localdomain (unknown [IPv6:2610:98:8005::527])\n\t(using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256\n\tbits))\n\t(No client certificate requested) (Authenticated sender: nicolas)\n\tby bhuna.collabora.co.uk (Postfix) with ESMTPSA id 008E52970E7;\n\tFri, 6 Mar 2020 20:27:12 +0000 (GMT)"],"From":"Nicolas Dufresne ","To":"libcamera-devel@lists.libcamera.org","Cc":"Jakub Adam ","Date":"Fri, 6 Mar 2020 15:26:36 -0500","Message-Id":"<20200306202637.525587-27-nicolas@ndufresne.ca>","X-Mailer":"git-send-email 2.24.1","In-Reply-To":"<20200306202637.525587-1-nicolas@ndufresne.ca>","References":"<20200306202637.525587-1-nicolas@ndufresne.ca>","MIME-Version":"1.0","Content-Transfer-Encoding":"8bit","Subject":"[libcamera-devel] [PATCH v3 26/27] gst: libcamerasrc: Prevent src\n\ttask deadlock on exhausted buffer pool","X-BeenThere":"libcamera-devel@lists.libcamera.org","X-Mailman-Version":"2.1.29","Precedence":"list","List-Id":"","List-Unsubscribe":",\n\t","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n\t","X-List-Received-Date":"Fri, 06 Mar 2020 20:27:13 -0000"},"content":"From: Jakub Adam \n\nAllow GstLibcameraPool to notify the source when a new buffer has become\navailable in a previously exhausted buffer pool. This can be used to\nresume a src task that got paused because it couldn't acquire a buffer.\n\nWithout this change the src task will never resume from pause once the\npool gets exhausted.\n\nTo trigger the deadlock (it doesn't happen every time), run:\n\n gst-launch-1.0 libcamerasrc ! queue ! glimagesink\n\nSigned-off-by: Jakub Adam \n---\n src/gstreamer/gstlibcamerapool.cpp | 17 +++++++++++++++++\n src/gstreamer/gstlibcamerasrc.cpp | 5 ++++-\n 2 files changed, 21 insertions(+), 1 deletion(-)","diff":"diff --git a/src/gstreamer/gstlibcamerapool.cpp b/src/gstreamer/gstlibcamerapool.cpp\nindex 3868905..8f53616 100644\n--- a/src/gstreamer/gstlibcamerapool.cpp\n+++ b/src/gstreamer/gstlibcamerapool.cpp\n@@ -14,6 +14,13 @@\n \n using namespace libcamera;\n \n+enum {\n+\tSIGNAL_BUFFER_NOTIFY,\n+\tN_SIGNALS\n+};\n+\n+static guint signals[N_SIGNALS];\n+\n struct _GstLibcameraPool {\n \tGstBufferPool parent;\n \n@@ -55,7 +62,12 @@ static void\n gst_libcamera_pool_release_buffer(GstBufferPool *pool, GstBuffer *buffer)\n {\n \tGstLibcameraPool *self = GST_LIBCAMERA_POOL(pool);\n+\tbool do_notify = gst_atomic_queue_length(self->queue) == 0;\n+\n \tgst_atomic_queue_push(self->queue, buffer);\n+\n+\tif (do_notify)\n+\t\tg_signal_emit(self, signals[SIGNAL_BUFFER_NOTIFY], 0);\n }\n \n static void\n@@ -90,6 +102,11 @@ gst_libcamera_pool_class_init(GstLibcameraPoolClass *klass)\n \tpool_class->acquire_buffer = gst_libcamera_pool_acquire_buffer;\n \tpool_class->reset_buffer = gst_libcamera_pool_reset_buffer;\n \tpool_class->release_buffer = gst_libcamera_pool_release_buffer;\n+\n+\tsignals[SIGNAL_BUFFER_NOTIFY] = g_signal_new(\"buffer-notify\",\n+\t\t\t\t\t\t G_OBJECT_CLASS_TYPE(klass), G_SIGNAL_RUN_LAST,\n+\t\t\t\t\t\t 0, nullptr, nullptr, nullptr,\n+\t\t\t\t\t\t G_TYPE_NONE, 0);\n }\n \n GstLibcameraPool *\ndiff --git a/src/gstreamer/gstlibcamerasrc.cpp b/src/gstreamer/gstlibcamerasrc.cpp\nindex 22d9175..9755922 100644\n--- a/src/gstreamer/gstlibcamerasrc.cpp\n+++ b/src/gstreamer/gstlibcamerasrc.cpp\n@@ -439,6 +439,9 @@ gst_libcamera_src_task_enter(GstTask *task, GThread *thread, gpointer user_data)\n \t\tconst StreamConfiguration &stream_cfg = state->config_->at(i);\n \t\tGstLibcameraPool *pool = gst_libcamera_pool_new(self->allocator,\n \t\t\t\t\t\t\t\tstream_cfg.stream());\n+\t\tg_signal_connect_swapped(pool, \"buffer-notify\",\n+\t\t\t\t\t G_CALLBACK(gst_libcamera_resume_task), task);\n+\n \t\tgst_libcamera_pad_set_pool(srcpad, pool);\n \t\tgst_flow_combiner_add_pad(self->flow_combiner, srcpad);\n \t}\n@@ -474,7 +477,7 @@ gst_libcamera_src_task_leave(GstTask *task, GThread *thread, gpointer user_data)\n \tstate->cam_->stop();\n \n \tfor (GstPad *srcpad : state->srcpads_)\n-\t\tgst_libcamera_pad_set_pool(srcpad, NULL);\n+\t\tgst_libcamera_pad_set_pool(srcpad, nullptr);\n \n \tg_clear_object(&self->allocator);\n \tg_clear_pointer(&self->flow_combiner,\n","prefixes":["libcamera-devel","v3","26/27"]}