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{ "id": 16446, "url": "https://patchwork.libcamera.org/api/patches/16446/?format=api", "web_url": "https://patchwork.libcamera.org/patch/16446/", "project": { "id": 1, "url": "https://patchwork.libcamera.org/api/projects/1/?format=api", "name": "libcamera", "link_name": "libcamera", "list_id": "libcamera_core", "list_email": "libcamera-devel@lists.libcamera.org", "web_url": "", "scm_url": "", "webscm_url": "" }, "msgid": "<20220630000251.31295-10-laurent.pinchart@ideasonboard.com>", "date": "2022-06-30T00:02:48", "name": "[libcamera-devel,v2,09/12] gstreamer: Fix pads locking", "commit_ref": null, "pull_url": null, "state": "accepted", "archived": false, "hash": "e53a8c0e782ccab4c31f5854a8efca039fd0ad3f", "submitter": { "id": 2, "url": "https://patchwork.libcamera.org/api/people/2/?format=api", "name": "Laurent Pinchart", "email": "laurent.pinchart@ideasonboard.com" }, "delegate": null, "mbox": "https://patchwork.libcamera.org/patch/16446/mbox/", "series": [ { "id": 3234, "url": "https://patchwork.libcamera.org/api/series/3234/?format=api", "web_url": "https://patchwork.libcamera.org/project/libcamera/list/?series=3234", "date": "2022-06-30T00:02:39", "name": "gstreamer: Queue multiple requests", "version": 2, "mbox": "https://patchwork.libcamera.org/series/3234/mbox/" } ], "comments": "https://patchwork.libcamera.org/api/patches/16446/comments/", "check": "pending", "checks": "https://patchwork.libcamera.org/api/patches/16446/checks/", "tags": {}, "headers": { "Return-Path": "<libcamera-devel-bounces@lists.libcamera.org>", "X-Original-To": "parsemail@patchwork.libcamera.org", "Delivered-To": "parsemail@patchwork.libcamera.org", "Received": [ "from lancelot.ideasonboard.com (lancelot.ideasonboard.com\n\t[92.243.16.209])\n\tby patchwork.libcamera.org (Postfix) with ESMTPS id E8163BD808\n\tfor <parsemail@patchwork.libcamera.org>;\n\tThu, 30 Jun 2022 00:03:33 +0000 (UTC)", "from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 89A1965657;\n\tThu, 30 Jun 2022 02:03:33 +0200 (CEST)", "from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[IPv6:2001:4b98:dc2:55:216:3eff:fef7:d647])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 4B2F765645\n\tfor <libcamera-devel@lists.libcamera.org>;\n\tThu, 30 Jun 2022 02:03:19 +0200 (CEST)", "from pendragon.lan (62-78-145-57.bb.dnainternet.fi [62.78.145.57])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id CC7E274A;\n\tThu, 30 Jun 2022 02:03:18 +0200 (CEST)" ], "DKIM-Signature": [ "v=1; 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dkim=pass (1024-bit key; \n\tunprotected) header.d=ideasonboard.com\n\theader.i=@ideasonboard.com\n\theader.b=\"ABZ9FhkL\"; dkim-atps=neutral", "To": "libcamera-devel@lists.libcamera.org", "Date": "Thu, 30 Jun 2022 03:02:48 +0300", "Message-Id": "<20220630000251.31295-10-laurent.pinchart@ideasonboard.com>", "X-Mailer": "git-send-email 2.35.1", "In-Reply-To": "<20220630000251.31295-1-laurent.pinchart@ideasonboard.com>", "References": "<20220630000251.31295-1-laurent.pinchart@ideasonboard.com>", "MIME-Version": "1.0", "Content-Transfer-Encoding": "8bit", "Subject": "[libcamera-devel] [PATCH v2 09/12] gstreamer: Fix pads locking", "X-BeenThere": "libcamera-devel@lists.libcamera.org", "X-Mailman-Version": "2.1.29", "Precedence": "list", "List-Id": "<libcamera-devel.lists.libcamera.org>", "List-Unsubscribe": "<https://lists.libcamera.org/options/libcamera-devel>,\n\t<mailto:libcamera-devel-request@lists.libcamera.org?subject=unsubscribe>", "List-Archive": "<https://lists.libcamera.org/pipermail/libcamera-devel/>", "List-Post": "<mailto:libcamera-devel@lists.libcamera.org>", "List-Help": "<mailto:libcamera-devel-request@lists.libcamera.org?subject=help>", "List-Subscribe": "<https://lists.libcamera.org/listinfo/libcamera-devel>,\n\t<mailto:libcamera-devel-request@lists.libcamera.org?subject=subscribe>", "From": "Laurent Pinchart via libcamera-devel\n\t<libcamera-devel@lists.libcamera.org>", "Reply-To": "Laurent Pinchart <laurent.pinchart@ideasonboard.com>", "Cc": "Nicolas Dufresne <nicolas.dufresne@collabora.com>", "Errors-To": "libcamera-devel-bounces@lists.libcamera.org", "Sender": "\"libcamera-devel\" <libcamera-devel-bounces@lists.libcamera.org>" }, "content": "The srcpads_ vector is protected by two different locks, the GstObject\nlock of the libcamerasrc element, and the stream_lock that covers the\nrun function of the thread. This isn't correct. Use the stream_lock\nconsistently to protect the pads.\n\nSigned-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>\nReviewed-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>\n---\nChanges since v1:\n\n- Add a comment about lock ordering\n---\n src/gstreamer/gstlibcamerasrc.cpp | 73 +++++++++++++++++--------------\n 1 file changed, 40 insertions(+), 33 deletions(-)", "diff": "diff --git a/src/gstreamer/gstlibcamerasrc.cpp b/src/gstreamer/gstlibcamerasrc.cpp\nindex 6f9a03c515d2..c92ca7d29fe6 100644\n--- a/src/gstreamer/gstlibcamerasrc.cpp\n+++ b/src/gstreamer/gstlibcamerasrc.cpp\n@@ -112,12 +112,18 @@ struct GstLibcameraSrcState {\n \tstd::shared_ptr<CameraManager> cm_;\n \tstd::shared_ptr<Camera> cam_;\n \tstd::unique_ptr<CameraConfiguration> config_;\n-\tstd::vector<GstPad *> srcpads_;\n+\n+\tstd::vector<GstPad *> srcpads_; /* Protected by stream_lock */\n \n \t/*\n \t * Contention on this lock_ must be minimized, as it has to be taken in\n \t * the realtime-sensitive requestCompleted() handler to protect\n \t * queuedRequests_ and completedRequests_.\n+\t *\n+\t * stream_lock must be taken before lock_ in contexts where both locks\n+\t * need to be taken. In particular, this means that the lock_ must not\n+\t * be held while calling into other graph elements (e.g. when calling\n+\t * gst_pad_query()).\n \t */\n \tMutex lock_;\n \tstd::queue<std::unique_ptr<RequestWrap>> queuedRequests_\n@@ -354,36 +360,34 @@ gst_libcamera_src_task_run(gpointer user_data)\n \t\t\t\t\t\t\tsrcpad, ret);\n \t}\n \n+\tif (ret != GST_FLOW_OK) {\n+\t\tif (ret == GST_FLOW_EOS) {\n+\t\t\tg_autoptr(GstEvent) eos = gst_event_new_eos();\n+\t\t\tguint32 seqnum = gst_util_seqnum_next();\n+\t\t\tgst_event_set_seqnum(eos, seqnum);\n+\t\t\tfor (GstPad *srcpad : state->srcpads_)\n+\t\t\t\tgst_pad_push_event(srcpad, gst_event_ref(eos));\n+\t\t} else if (ret != GST_FLOW_FLUSHING) {\n+\t\t\tGST_ELEMENT_FLOW_ERROR(self, ret);\n+\t\t}\n+\t\tgst_task_stop(self->task);\n+\t\treturn;\n+\t}\n+\n+\t/*\n+\t * Here we need to decide if we want to pause. This needs to\n+\t * happen in lock step with the callback thread which may want\n+\t * to resume the task and might push pending buffers.\n+\t */\n+\tbool do_pause;\n+\n \t{\n-\t\tif (ret != GST_FLOW_OK) {\n-\t\t\tif (ret == GST_FLOW_EOS) {\n-\t\t\t\tg_autoptr(GstEvent) eos = gst_event_new_eos();\n-\t\t\t\tguint32 seqnum = gst_util_seqnum_next();\n-\t\t\t\tgst_event_set_seqnum(eos, seqnum);\n-\t\t\t\tfor (GstPad *srcpad : state->srcpads_)\n-\t\t\t\t\tgst_pad_push_event(srcpad, gst_event_ref(eos));\n-\t\t\t} else if (ret != GST_FLOW_FLUSHING) {\n-\t\t\t\tGST_ELEMENT_FLOW_ERROR(self, ret);\n-\t\t\t}\n-\t\t\tgst_task_stop(self->task);\n-\t\t\treturn;\n-\t\t}\n-\n-\t\t/*\n-\t\t * Here we need to decide if we want to pause. This needs to\n-\t\t * happen in lock step with the callback thread which may want\n-\t\t * to resume the task and might push pending buffers.\n-\t\t */\n-\t\tbool do_pause;\n-\n-\t\t{\n-\t\t\tMutexLocker locker(state->lock_);\n-\t\t\tdo_pause = state->completedRequests_.empty();\n-\t\t}\n-\n-\t\tif (do_pause)\n-\t\t\tgst_task_pause(self->task);\n+\t\tMutexLocker locker(state->lock_);\n+\t\tdo_pause = state->completedRequests_.empty();\n \t}\n+\n+\tif (do_pause)\n+\t\tgst_task_pause(self->task);\n }\n \n static void\n@@ -537,8 +541,11 @@ gst_libcamera_src_task_leave([[maybe_unused]] GstTask *task,\n \t\tstate->completedRequests_ = {};\n \t}\n \n-\tfor (GstPad *srcpad : state->srcpads_)\n-\t\tgst_libcamera_pad_set_pool(srcpad, nullptr);\n+\t{\n+\t\tGLibRecLocker locker(&self->stream_lock);\n+\t\tfor (GstPad *srcpad : state->srcpads_)\n+\t\t\tgst_libcamera_pad_set_pool(srcpad, nullptr);\n+\t}\n \n \tg_clear_object(&self->allocator);\n \tg_clear_pointer(&self->flow_combiner,\n@@ -697,7 +704,7 @@ gst_libcamera_src_request_new_pad(GstElement *element, GstPadTemplate *templ,\n \tg_object_ref_sink(pad);\n \n \tif (gst_element_add_pad(element, pad)) {\n-\t\tGLibLocker lock(GST_OBJECT(self));\n+\t\tGLibRecLocker lock(&self->stream_lock);\n \t\tself->state->srcpads_.push_back(reinterpret_cast<GstPad *>(g_object_ref(pad)));\n \t} else {\n \t\tGST_ELEMENT_ERROR(element, STREAM, FAILED,\n@@ -717,7 +724,7 @@ gst_libcamera_src_release_pad(GstElement *element, GstPad *pad)\n \tGST_DEBUG_OBJECT(self, \"Pad %\" GST_PTR_FORMAT \" being released\", pad);\n \n \t{\n-\t\tGLibLocker lock(GST_OBJECT(self));\n+\t\tGLibRecLocker lock(&self->stream_lock);\n \t\tstd::vector<GstPad *> &pads = self->state->srcpads_;\n \t\tauto begin_iterator = pads.begin();\n \t\tauto end_iterator = pads.end();\n", "prefixes": [ "libcamera-devel", "v2", "09/12" ] }