From patchwork Tue Jan 23 01:12:41 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Laurent Pinchart X-Patchwork-Id: 19452 Return-Path: X-Original-To: parsemail@patchwork.libcamera.org Delivered-To: parsemail@patchwork.libcamera.org Received: from lancelot.ideasonboard.com (lancelot.ideasonboard.com [92.243.16.209]) by patchwork.libcamera.org (Postfix) with ESMTPS id BB774C32BE for ; Tue, 23 Jan 2024 01:12:54 +0000 (UTC) Received: from lancelot.ideasonboard.com (localhost [IPv6:::1]) by lancelot.ideasonboard.com (Postfix) with ESMTP id 89C2F62955; Tue, 23 Jan 2024 02:12:53 +0100 (CET) Authentication-Results: lancelot.ideasonboard.com; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="XRUGVev6"; dkim-atps=neutral Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [IPv6:2001:4b98:dc2:55:216:3eff:fef7:d647]) by lancelot.ideasonboard.com (Postfix) with ESMTPS id 793F06294A for ; Tue, 23 Jan 2024 02:12:51 +0100 (CET) Received: from pendragon.ideasonboard.com (89-27-53-110.bb.dnainternet.fi [89.27.53.110]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 33CB4E4; Tue, 23 Jan 2024 02:11:38 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1705972298; bh=v+MZe0izlr8b1qKd6q3sOfkw+6ac0wk5IMNQfH6J0LY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=XRUGVev6EsMac/5eQqO8SZ5CZcZdSLaVTaW/tB+zMKzgelWOzBqJ3ywCJy9ZgzLLG QUfJxbXvxR5HIttnaX7gQtuMtNIAysFdZKHsJsQ6FiE+s0eAx/uuXVh1o7L6/2W0bu cYvIZGdt14Wm5KayDnlEhPknq4oB42oFpQ0R4KI0= From: Laurent Pinchart To: libcamera-devel@lists.libcamera.org Subject: [PATCH v2 04/12] libcamera: thread: Ensure deferred deletion of all objects before stopping Date: Tue, 23 Jan 2024 03:12:41 +0200 Message-ID: <20240123011249.22716-5-laurent.pinchart@ideasonboard.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240123011249.22716-1-laurent.pinchart@ideasonboard.com> References: <20240123011249.22716-1-laurent.pinchart@ideasonboard.com> MIME-Version: 1.0 X-BeenThere: libcamera-devel@lists.libcamera.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: libcamera-devel-bounces@lists.libcamera.org Sender: "libcamera-devel" Objects can be scheduled for deletion with Object::deleteLater(), which queues a deferred deletion to the thread's event loop. As the deleteLater() function is meant to be called from a different thread, this may race with thread termination, and deferred deletions queued just before calling Thread::exit() may not be processed by the event loop. Make sure they get processed when finishing the thread, before stopping. This eliminates the race condition that occurs when calling Object::deleteLater() followed by Thread::exit() from the same thread. Calling deleteLater() from neither the thread the object is bound to or the thread calling Thread::exit() is still inherently racy. The change fixes a failure in the object-delete unit test. Signed-off-by: Laurent Pinchart Reviewed-by: Milan Zamazal --- Changes since v1: - Expand commit message - Update the Object::deleteLater() documentation --- src/libcamera/base/object.cpp | 5 +++-- src/libcamera/base/thread.cpp | 6 ++++++ 2 files changed, 9 insertions(+), 2 deletions(-) diff --git a/src/libcamera/base/object.cpp b/src/libcamera/base/object.cpp index 1fce5a2af9af..14399d750e03 100644 --- a/src/libcamera/base/object.cpp +++ b/src/libcamera/base/object.cpp @@ -116,8 +116,9 @@ Object::~Object() * event loop that the object belongs to. This ensures the object is destroyed * from the right context, as required by the libcamera threading model. * - * If this function is called before the thread's event loop is started, the - * object will be deleted when the event loop starts. + * If this function is called before the thread's event loop is started or after + * it has stopped, the object will be deleted when the event loop (re)starts. If + * this never occurs, the object will be leaked. * * Deferred deletion can be used to control the destruction context with shared * pointers. An object managed with shared pointers is deleted when the last diff --git a/src/libcamera/base/thread.cpp b/src/libcamera/base/thread.cpp index 75693c92a0b1..4ac72036aa69 100644 --- a/src/libcamera/base/thread.cpp +++ b/src/libcamera/base/thread.cpp @@ -371,6 +371,12 @@ void Thread::run() void Thread::finishThread() { + /* + * Objects may have been scheduled for deletion right before the thread + * exited. Ensure they get deleted now, before the thread stops. + */ + dispatchMessages(Message::Type::DeferredDelete); + data_->mutex_.lock(); data_->running_ = false; data_->mutex_.unlock();