From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DEFAA4BFE8D; Tue, 15 Sep 2026 11:34:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789472081; cv=none; b=TnW9k8I4elIfamziNMXeAZVV1rfVQnSJjc/jN5hyvbLQtKFpnvYLS8uTZk5RluPfJ7rf0QUZOt6hAhvZop8n64BWYTASNi7azOdd26UfGcrx5jvxEpXtdS5+MeN+kP0vTA+JWTg+SefC00hWfVt+9nbotEZNHv4+5l0taVLXteE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789472081; c=relaxed/simple; bh=WVbD0pO6d4mjiUvlOLIjL57eEEjsBq56vpsfDeJomcY=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=i5n+hWkgw5sR+znWKq2eg0fIQh06IJa4wmEpCfQtkP6uHHdvDHnFevE3sJMNcGG8oKHaC6Q6FIYzrsw4FByd0vRZsZrb9w40E5zYUrtXeu3gzQlLhRGa6Nm9XH3GbaU+lwz7eSkR55IQxMPRhpYqXUCp64zD+H92hBMaxb0K/ME= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=NLbpzRry; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="NLbpzRry" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 77FDC1F00893; Tue, 15 Sep 2026 11:34:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789472079; bh=cDPO1Tppu7zGiZS0wqcZiTuTwlavGuE/rjDjnQsBE8E=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=NLbpzRryDp6dFPNq2d5OJvruDzyZONEFg64LrDUeM5ugsoft5S7pBeG/pH66NE5IL 3K1p9eHLYNaeeDaMavKCpdAseqox6l5EnfcT+KopXRUVpAGLpJ9yfjtXkfsEViD35p ADMqHomqefTxla65WmYonAYRk046Vz0TUnURPnhxUASNKqUUkNdFTTmZNpEDsrmsBU 6GsRHd/hVex1t+bazl57XSA3/fWSISHGQVrMQ+hQ7z2QElRmXKMZdLoquUEY4uZ9o0 wbzzdJN3unzzMqJSYGFB8PGFSj10gPRo7LK7HDW022JXae9+9AS0j5tXO3J4dwtg5G rF8s/BzuCbuwQ== From: Christian Brauner Date: Tue, 15 Sep 2026 13:31:12 +0200 Subject: [PATCH RFC POC 26/50] dma-buf: stop unwinding sync file descriptors by hand Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260915-work-fd-reserve-unify-folded-v1-26-4d5217d6b246@kernel.org> References: <20260915-work-fd-reserve-unify-folded-v1-0-4d5217d6b246@kernel.org> In-Reply-To: <20260915-work-fd-reserve-unify-folded-v1-0-4d5217d6b246@kernel.org> To: Linus Torvalds Cc: Alexander Viro , Jann Horn , Jan Kara , Ingo Molnar , Peter Zijlstra , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Oleg Nesterov , linux-alpha@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-csky@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, linux-openrisc@vger.kernel.org, linux-parisc@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-um@lists.infradead.org, Jens Axboe , io-uring@vger.kernel.org, netdev@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-gpio@vger.kernel.org, linux-arm-msm@vger.kernel.org, dri-devel@lists.freedesktop.org, bpf@vger.kernel.org, David Airlie , virtualization@lists.linux.dev, kvm@vger.kernel.org, kexec@lists.infradead.org, linux-hyperv@vger.kernel.org, "Christian Brauner (Amutable)" X-Mailer: b4 0.17-dev-db0b7 X-Developer-Signature: v=1; a=openpgp-sha256; l=5768; i=brauner@kernel.org; h=from:subject:message-id; bh=WVbD0pO6d4mjiUvlOLIjL57eEEjsBq56vpsfDeJomcY=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMWSt1Klbx7fSV2vzb4mztp+e+U8pjOoJ5RRLmcKaIWU0y e1svXhCRykLgxgXg6yYIotDu0m43HKeis1GmRowc1iZQIYwcHEKwEQM9zMyHNVclB75UIUtlMkq +oqP/KHwKflt//9e3LImMGbio3sWXQz/448uNWN/83aF2Gujxje/v7ndnOYetv30l/bU9fpNKqo 7eQE= X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 Rely on the fd exit path machinery. Signed-off-by: Christian Brauner (Amutable) --- drivers/dma-buf/dma-buf.c | 33 ++++++++++------------------ drivers/dma-buf/sw_sync.c | 40 +++++++++++----------------------- drivers/dma-buf/sync_file.c | 52 +++++++++++++-------------------------------- 3 files changed, 38 insertions(+), 87 deletions(-) diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index d504c636dc29..f0d581fad7ae 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -440,7 +440,8 @@ static long dma_buf_export_sync_file(struct dma_buf *dmabuf, enum dma_resv_usage usage; struct dma_fence *fence = NULL; struct sync_file *sync_file; - int fd, ret; + int ret; + const struct fd_slot *fd; if (copy_from_user(&arg, user_data, sizeof(arg))) return -EFAULT; @@ -451,14 +452,14 @@ static long dma_buf_export_sync_file(struct dma_buf *dmabuf, if ((arg.flags & DMA_BUF_SYNC_RW) == 0) return -EINVAL; - fd = get_unused_fd_flags(O_CLOEXEC); - if (fd < 0) - return fd; + fd = fd_prepare(O_CLOEXEC); + if (IS_ERR(fd)) + return PTR_ERR(fd); usage = dma_resv_usage_rw(arg.flags & DMA_BUF_SYNC_WRITE); ret = dma_resv_get_singleton(dmabuf->resv, usage, &fence); if (ret) - goto err_put_fd; + return ret; if (!fence) fence = dma_fence_get_stub(); @@ -467,26 +468,14 @@ static long dma_buf_export_sync_file(struct dma_buf *dmabuf, dma_fence_put(fence); - if (!sync_file) { - ret = -ENOMEM; - goto err_put_fd; - } - - arg.fd = fd; - if (copy_to_user(user_data, &arg, sizeof(arg))) { - ret = -EFAULT; - goto err_put_file; - } + if (!sync_file) + return -ENOMEM; - fd_install(fd, sync_file->file); + arg.fd = fd_stage(fd, sync_file->file); + if (copy_to_user(user_data, &arg, sizeof(arg))) + return -EFAULT; return 0; - -err_put_file: - fput(sync_file->file); -err_put_fd: - put_unused_fd(fd); - return ret; } static long dma_buf_import_sync_file(struct dma_buf *dmabuf, diff --git a/drivers/dma-buf/sw_sync.c b/drivers/dma-buf/sw_sync.c index 8df20b0218a9..90852950e4e3 100644 --- a/drivers/dma-buf/sw_sync.c +++ b/drivers/dma-buf/sw_sync.c @@ -344,8 +344,7 @@ static int sw_sync_debugfs_release(struct inode *inode, struct file *file) static long sw_sync_ioctl_create_fence(struct sync_timeline *obj, unsigned long arg) { - int fd = get_unused_fd_flags(O_CLOEXEC); - int err; + const struct fd_slot *fd = fd_prepare(O_CLOEXEC); struct sync_pt *pt; struct sync_file *sync_file; struct sw_sync_create_fence_data data; @@ -353,41 +352,26 @@ static long sw_sync_ioctl_create_fence(struct sync_timeline *obj, /* SW sync fence are inherently unsafe and can deadlock the kernel */ add_taint(TAINT_SOFTLOCKUP, LOCKDEP_STILL_OK); - if (fd < 0) - return fd; + if (IS_ERR(fd)) + return PTR_ERR(fd); - if (copy_from_user(&data, (void __user *)arg, sizeof(data))) { - err = -EFAULT; - goto err; - } + if (copy_from_user(&data, (void __user *)arg, sizeof(data))) + return -EFAULT; pt = sync_pt_create(obj, data.value); - if (!pt) { - err = -ENOMEM; - goto err; - } + if (!pt) + return -ENOMEM; sync_file = sync_file_create(&pt->base); dma_fence_put(&pt->base); - if (!sync_file) { - err = -ENOMEM; - goto err; - } - - data.fence = fd; - if (copy_to_user((void __user *)arg, &data, sizeof(data))) { - fput(sync_file->file); - err = -EFAULT; - goto err; - } + if (!sync_file) + return -ENOMEM; - fd_install(fd, sync_file->file); + data.fence = fd_stage(fd, sync_file->file); + if (copy_to_user((void __user *)arg, &data, sizeof(data))) + return -EFAULT; return 0; - -err: - put_unused_fd(fd); - return err; } static long sw_sync_ioctl_inc(struct sync_timeline *obj, unsigned long arg) diff --git a/drivers/dma-buf/sync_file.c b/drivers/dma-buf/sync_file.c index 2166bbdf7e4a..316fffc4067e 100644 --- a/drivers/dma-buf/sync_file.c +++ b/drivers/dma-buf/sync_file.c @@ -213,56 +213,34 @@ static __poll_t sync_file_poll(struct file *file, poll_table *wait) static long sync_file_ioctl_merge(struct sync_file *sync_file, unsigned long arg) { - int fd = get_unused_fd_flags(O_CLOEXEC); - int err; + const struct fd_slot *fd = fd_prepare(O_CLOEXEC); struct sync_file *fence2, *fence3; struct sync_merge_data data; - if (fd < 0) - return fd; + if (IS_ERR(fd)) + return PTR_ERR(fd); - if (copy_from_user(&data, (void __user *)arg, sizeof(data))) { - err = -EFAULT; - goto err_put_fd; - } + if (copy_from_user(&data, (void __user *)arg, sizeof(data))) + return -EFAULT; - if (data.flags || data.pad) { - err = -EINVAL; - goto err_put_fd; - } + if (data.flags || data.pad) + return -EINVAL; fence2 = sync_file_fdget(data.fd2); - if (!fence2) { - err = -ENOENT; - goto err_put_fd; - } + if (!fence2) + return -ENOENT; data.name[sizeof(data.name) - 1] = '\0'; fence3 = sync_file_merge(data.name, sync_file, fence2); - if (!fence3) { - err = -ENOMEM; - goto err_put_fence2; - } - - data.fence = fd; - if (copy_to_user((void __user *)arg, &data, sizeof(data))) { - err = -EFAULT; - goto err_put_fence3; - } - - fd_install(fd, fence3->file); fput(fence2->file); - return 0; - -err_put_fence3: - fput(fence3->file); + if (!fence3) + return -ENOMEM; -err_put_fence2: - fput(fence2->file); + data.fence = fd_stage(fd, fence3->file); + if (copy_to_user((void __user *)arg, &data, sizeof(data))) + return -EFAULT; -err_put_fd: - put_unused_fd(fd); - return err; + return 0; } static int sync_fill_fence_info(struct dma_fence *fence, -- 2.53.0