From 76d7b84bfa43f514544477d2282f9ac9796a2594 Mon Sep 17 00:00:00 2001 From: Viresh Kumar Date: Wed, 27 Jul 2016 14:32:58 -0700 Subject: [PATCH] dmaengine: device must have at least one channel 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 Signed-off-by: Vinod Koul --- 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); -- 2.20.1