| To: | dan.j.williams@intel.com |
|---|---|
| Subject: | Re: [PATCH 1/2] dmaengine: TXx9 Soc DMA Controller driver |
| From: | Atsushi Nemoto <anemo@mba.ocn.ne.jp> |
| Date: | Wed, 18 Mar 2009 09:49:35 +0900 (JST) |
| Cc: | linux-mips@linux-mips.org, ralf@linux-mips.org, linux-kernel@vger.kernel.org, haavard.skinnemoen@atmel.com |
| In-reply-to: | <e9c3a7c20903171002n50964148v8366fa2f00e3164c@mail.gmail.com> |
| Original-recipient: | rfc822;linux-mips@linux-mips.org |
| References: | <e9c3a7c20903162152w6b73b4b8hba8004e7b349c447@mail.gmail.com> <20090318.010939.128619068.anemo@mba.ocn.ne.jp> <e9c3a7c20903171002n50964148v8366fa2f00e3164c@mail.gmail.com> |
| Sender: | linux-mips-bounce@linux-mips.org |
On Tue, 17 Mar 2009 10:02:14 -0700, Dan Williams <dan.j.williams@intel.com> wrote: > >> The sysfs device has a longer lifetime than dma_device. See commit > >> 41d5e59c [1]. > > > > The sysfs device for dma_chan (dma_chan_dev) has a shorter lifetime > > than dma_device, doesn't it? > > No, dma_async_device_unregister(), and the freeing of dma_device, may > finish before chan_dev_release is called. Userspace gates the final > release of dma_chan_dev objects. You mean, if the sysfs device file was opened when dma_async_device_unregister() was called, the sysfs device will not be released until the sysfs device file is closed, right? If so I can see. BTW, there are another holes in dma_async_device_register. If idr_pre_get or idr_get_new was failed, idr_ref will not be freed. --- Atsushi Nemoto |
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