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{ "id": 13494, "url": "https://patchwork.libcamera.org/api/patches/13494/?format=api", "web_url": "https://patchwork.libcamera.org/patch/13494/", "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": "<20210825211852.1207168-2-nicolas@ndufresne.ca>", "date": "2021-08-25T21:18:50", "name": "[libcamera-devel,v1,1/3] gstreamer: Fix deadlock when last allocator ref is held by buffer", "commit_ref": null, "pull_url": null, "state": "accepted", "archived": false, "hash": "21d5f46109b69cecc45d1edded7c0138359d5183", "submitter": { "id": 30, "url": "https://patchwork.libcamera.org/api/people/30/?format=api", "name": "Nicolas Dufresne", "email": "nicolas@ndufresne.ca" }, "delegate": null, "mbox": "https://patchwork.libcamera.org/patch/13494/mbox/", "series": [ { "id": 2396, "url": "https://patchwork.libcamera.org/api/series/2396/?format=api", "web_url": "https://patchwork.libcamera.org/project/libcamera/list/?series=2396", "date": "2021-08-25T21:18:49", "name": "Fix Gnome Cheese and multiple camera", "version": 1, "mbox": "https://patchwork.libcamera.org/series/2396/mbox/" } ], "comments": "https://patchwork.libcamera.org/api/patches/13494/comments/", "check": "pending", "checks": "https://patchwork.libcamera.org/api/patches/13494/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 0C4F2BD87D\n\tfor <parsemail@patchwork.libcamera.org>;\n\tWed, 25 Aug 2021 21:19:15 +0000 (UTC)", "from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id D537968893;\n\tWed, 25 Aug 2021 23:19:14 +0200 (CEST)", "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 03F9760288\n\tfor <libcamera-devel@lists.libcamera.org>;\n\tWed, 25 Aug 2021 23:19:13 +0200 (CEST)", "from [127.0.0.1] (localhost [127.0.0.1])\n\t(Authenticated sender: nicolas) with ESMTPSA id 49C0E1F435D8" ], "From": "Nicolas Dufresne <nicolas@ndufresne.ca>", "To": "libcamera-devel@lists.libcamera.org", "Date": "Wed, 25 Aug 2021 17:18:50 -0400", "Message-Id": "<20210825211852.1207168-2-nicolas@ndufresne.ca>", "X-Mailer": "git-send-email 2.31.1", "In-Reply-To": "<20210825211852.1207168-1-nicolas@ndufresne.ca>", "References": "<20210825211852.1207168-1-nicolas@ndufresne.ca>", "MIME-Version": "1.0", "Content-Transfer-Encoding": "8bit", "Subject": "[libcamera-devel] [PATCH v1 1/3] gstreamer: Fix deadlock when last\n\tallocator ref is held by buffer", "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>", "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": "From: Nicolas Dufresne <nicolas.dufresne@collabora.com>\n\nThis deadlock occurs when a buffer is holding the last reference on\nthe allocator. In gst_libcamera_allocator_release() we must drop the\nobject lock before dropping the last ref of that object since the\ndestructor will lock it again causing deadlock.\n\nThis was notice while switching camera or resolution in Cheese software.\n\nSigned-off-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>\n---\n src/gstreamer/gstlibcameraallocator.cpp | 17 ++++++++++-------\n 1 file changed, 10 insertions(+), 7 deletions(-)", "diff": "diff --git a/src/gstreamer/gstlibcameraallocator.cpp b/src/gstreamer/gstlibcameraallocator.cpp\nindex 7bd8ba2d..a8fa4f86 100644\n--- a/src/gstreamer/gstlibcameraallocator.cpp\n+++ b/src/gstreamer/gstlibcameraallocator.cpp\n@@ -108,15 +108,18 @@ gst_libcamera_allocator_release(GstMiniObject *mini_object)\n {\n \tGstMemory *mem = GST_MEMORY_CAST(mini_object);\n \tGstLibcameraAllocator *self = GST_LIBCAMERA_ALLOCATOR(mem->allocator);\n-\tGLibLocker lock(GST_OBJECT(self));\n-\tauto *frame = reinterpret_cast<FrameWrap *>(gst_mini_object_get_qdata(mini_object, FrameWrap::getQuark()));\n \n-\tgst_memory_ref(mem);\n+\t{\n+\t\tGLibLocker lock(GST_OBJECT(self));\n+\t\tauto *frame = reinterpret_cast<FrameWrap *>(gst_mini_object_get_qdata(mini_object, FrameWrap::getQuark()));\n+\n+\t\tgst_memory_ref(mem);\n \n-\tif (frame->releasePlane()) {\n-\t\tauto *pool = reinterpret_cast<GQueue *>(g_hash_table_lookup(self->pools, frame->stream_));\n-\t\tg_return_val_if_fail(pool, TRUE);\n-\t\tg_queue_push_tail(pool, frame);\n+\t\tif (frame->releasePlane()) {\n+\t\t\tauto *pool = reinterpret_cast<GQueue *>(g_hash_table_lookup(self->pools, frame->stream_));\n+\t\t\tg_return_val_if_fail(pool, TRUE);\n+\t\t\tg_queue_push_tail(pool, frame);\n+\t\t}\n \t}\n \n \t/* Keep last in case we are holding on the last allocator ref. */\n", "prefixes": [ "libcamera-devel", "v1", "1/3" ] }