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From:   "Yang, Shunyong" <shunyong.yang@hxt-semitech.com>
To:     "vkoul@kernel.org" <vkoul@kernel.org>
CC:     "andy.gross@linaro.org" <andy.gross@linaro.org>,
        "david.brown@linaro.org" <david.brown@linaro.org>,
        Sinan Kaya <okaya@kernel.org>,
        "dan.j.williams@intel.com" <dan.j.williams@intel.com>,
        "dmaengine@vger.kernel.org" <dmaengine@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "Zheng, Joey" <yu.zheng@hxt-semitech.com>
Subject: Re: [PATCH 2/2] dmaengine: qcom_hidma: assign channel cookie
 correctly
Thread-Topic: [PATCH 2/2] dmaengine: qcom_hidma: assign channel cookie
 correctly
Thread-Index: AQHUjeVi0WVpnH1GL02j01lRgeSliA==
Date:   Fri, 4 Jan 2019 08:56:43 +0000
Message-ID: <16bbdd233f1d45249eb2f6592418efd5@HXTBJIDCEMVIW02.hxtcorp.net>
References: <81c9fe2de4b5dac1d5b974f5305e35bf1cf5d127.1544156508.git.shunyong.yang@hxt-semitech.com>
 <ea6c6317dabffdcfa28cdb391b50edce98ce875d.1544156508.git.shunyong.yang@hxt-semitech.com>
 <88ef21bd-4e4f-8cce-39b3-53da45740f0f@kernel.org>
 <79da1c31d3e14e6e91cf6a7cc0fea31a@HXTBJIDCEMVIW01.hxtcorp.net>
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Hi, Vinod,

Gentle ping. Would you please help to review these two patches and merge?

On 2018/12/14 9:03, Yang, Shunyong wrote:
> Hi, Sinan
> 
> On 2018/12/9 4:28, Sinan Kaya wrote:
>> On 12/6/2018 11:29 PM, Shunyong Yang wrote:
>>> When dma_cookie_complete() is called in hidma_process_completed(),
>>> dma_cookie_status() will return DMA_COMPLETE in hidma_tx_status(). Then,
>>> hidma_txn_is_success() will be called to use channel cookie
>>> mchan->last_success to do additional DMA status check. Current code
>>> assigns mchan->last_success after dma_cookie_complete(). This causes
>>> a race condition of dma_cookie_status() returns DMA_COMPLETE before
>>> mchan->last_success is assigned correctly. The race will cause
>>> hidma_tx_status() return DMA_ERROR but the transaction is actually a
>>> success. Moreover, in async_tx case, it will cause a timeout panic
>>> in async_tx_quiesce().
>>>
>>>   Kernel panic - not syncing: async_tx_quiesce: DMA error waiting for
>>>   transaction
>>>   ...
>>>   Call trace:
>>>   [<ffff000008089994>] dump_backtrace+0x0/0x1f4
>>>   [<ffff000008089bac>] show_stack+0x24/0x2c
>>>   [<ffff00000891e198>] dump_stack+0x84/0xa8
>>>   [<ffff0000080da544>] panic+0x12c/0x29c
>>>   [<ffff0000045d0334>] async_tx_quiesce+0xa4/0xc8 [async_tx]
>>>   [<ffff0000045d03c8>] async_trigger_callback+0x70/0x1c0 [async_tx]
>>>   [<ffff0000048b7d74>] raid_run_ops+0x86c/0x1540 [raid456]
>>>   [<ffff0000048bd084>] handle_stripe+0x5e8/0x1c7c [raid456]
>>>   [<ffff0000048be9ec>] handle_active_stripes.isra.45+0x2d4/0x550 [raid456]
>>>   [<ffff0000048beff4>] raid5d+0x38c/0x5d0 [raid456]
>>>   [<ffff000008736538>] md_thread+0x108/0x168
>>>   [<ffff0000080fb1cc>] kthread+0x10c/0x138
>>>   [<ffff000008084d34>] ret_from_fork+0x10/0x18
>>>
>>> Cc: Joey Zheng<yu.zheng@hxt-semitech.com>
>>> Signed-off-by: Shunyong Yang<shunyong.yang@hxt-semitech.com>
>>
>>
>> Acked-by: Sinan Kaya <okaya@kernel.org>
>>
>> to both patches 1/2 and 2/2.
>>
>>
> Thanks for the ACKs.
> 
> Shunyong.
> 
>