From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758648AbcG0VdM (ORCPT ); Wed, 27 Jul 2016 17:33:12 -0400 Received: from mail-pf0-f175.google.com ([209.85.192.175]:36247 "EHLO mail-pf0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751849AbcG0VdI (ORCPT ); Wed, 27 Jul 2016 17:33:08 -0400 From: Viresh Kumar To: Dan Williams , Vinod Koul Cc: linaro-kernel@lists.linaro.org, Greg Kroah-Hartman , Viresh Kumar , dmaengine@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] dmaengine: device must have at least one channel Date: Wed, 27 Jul 2016 14:32:58 -0700 Message-Id: <4a6e2283fb7736c33fb733c310314d7bc135cd6d.1469654853.git.viresh.kumar@linaro.org> X-Mailer: git-send-email 2.7.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The DMA device can't be registered if it doesn't have any channels registered at all. Moreover, it leads to memory leak and is reported by kmemleak as (on 3.10 kernel, and same shall happen on mainline): unreferenced object 0xffffffc09e597240 (size 64): comm "swapper/0", pid 1, jiffies 4294877736 (age 7060.280s) hex dump (first 32 bytes): 00 00 00 00 c0 ff ff ff 30 00 00 ff 00 00 00 ff ........0....... 00 00 00 ff 00 00 00 ff 00 00 00 ff 00 00 00 ff ................ backtrace: [] create_object+0x148/0x2a0 [] kmemleak_alloc+0x80/0xbc [] kmem_cache_alloc_trace+0x120/0x1ac [] dma_async_device_register+0x160/0x46c [] foo_probe+0x1a0/0x264 [] platform_drv_probe+0x14/0x20 [] driver_probe_device+0x160/0x374 [] __driver_attach+0x60/0x90 [] bus_for_each_dev+0x7c/0xb0 [] driver_attach+0x1c/0x28 [] bus_add_driver+0x124/0x248 [] driver_register+0x90/0x110 [] platform_driver_register+0x58/0x64 [] foo_driver_init+0x10/0x1c [] do_one_initcall+0xac/0x148 [] kernel_init_freeable+0x1a0/0x258 Return -ENODEV from dma_async_device_register() on such a case. Signed-off-by: Viresh Kumar --- Hi Vinod, Sorry if the fundamentals behind this patch are completely incorrect, i.e. We *can't* register a dma device with 0 channels. Its been long that I have worked on dma stuff :) drivers/dma/dmaengine.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c index 8c9f45fd55fc..6b535262ac5d 100644 --- a/drivers/dma/dmaengine.c +++ b/drivers/dma/dmaengine.c @@ -997,6 +997,13 @@ int dma_async_device_register(struct dma_device *device) } chan->client_count = 0; } + + if (!chancnt) { + dev_err(device->dev, "%s: device has no channels!\n", __func__); + rc = -ENODEV; + goto err_out; + } + device->chancnt = chancnt; mutex_lock(&dma_list_mutex); -- 2.7.4