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I was already wondering why the order is this way. Why is dma_buf_stats_setup() needing the file in the first place? Thanks, Christian. > > Hope these tips are useful, thanks! > > On 2022/11/24 13:56, Charan Teja Kalla wrote: >> Thanks T.J and Christian for the inputs. >> >> On 11/19/2022 7:00 PM, Christian König wrote: >>>>      Yes, exactly that's the idea. >>>> >>>>      The only alternatives I can see would be to either move >>>> allocating >>>>      the >>>>      file and so completing the dma_buf initialization last again >>>> or just >>>>      ignore errors from sysfs. >>>> >>>>      > If we still want to avoid calling >>>> dmabuf->ops->release(dmabuf) in >>>>      > dma_buf_release like the comment says I guess we could use >>>>      sysfs_entry >>>>      > and ERR_PTR to flag that, otherwise it looks like we'd need >>>> a bit >>>>      > somewhere. >>>> >>>>      No, this should be dropped as far as I can see. The sysfs cleanup >>>>      code >>>>      looks like it can handle not initialized kobj pointers. >>>> >>>> >>>> Yeah there is also the null check in dma_buf_stats_teardown() that >>>> would prevent it from running, but I understood the comment to be >>>> referring to the release() dma_buf_ops call into the exporter which >>>> comes right after the teardown call. That looks like it's preventing >>>> the fput task work calling back into the exporter after the exporter >>>> already got an error from dma_buf_export(). Otherwise the exporter >>>> sees a release() for a buffer that it doesn't know about / thinks >>>> shouldn't exist. So I could imagine an exporter trying to double free: >>>> once for the failed dma_buf_export() call, and again when the >>>> release() op is called later. >>> >>> Oh, very good point as well. Yeah, then creating the file should >>> probably come last. >>> >> @Gaosheng: Could you please make these changes or you let me to do? >> >>> Regards, >>> Christian. >> . 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Mercier" References: <20221117062152.3029018-1-cuigaosheng1@huawei.com> <99d3aee6-ba3e-5333-6f79-ddbcfc0e8843@amd.com> <2c9fa595-e788-5474-4f2b-ffbd08a70d13@amd.com> <83944425-c177-7918-bcde-9cf7296a613f@amd.com> From: =?UTF-8?Q?Christian_K=c3=b6nig?= In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-ClientProxiedBy: FR2P281CA0022.DEUP281.PROD.OUTLOOK.COM (2603:10a6:d10:14::9) To BN8PR12MB3587.namprd12.prod.outlook.com (2603:10b6:408:43::13) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BN8PR12MB3587:EE_|CH2PR12MB4086:EE_ X-MS-Office365-Filtering-Correlation-Id: e014ea8d-b097-4a64-f69b-08dace18b09b X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255; 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I was already wondering why the order is this way. Why is dma_buf_stats_setup() needing the file in the first place? Thanks, Christian. > > Hope these tips are useful, thanks! > > On 2022/11/24 13:56, Charan Teja Kalla wrote: >> Thanks T.J and Christian for the inputs. >> >> On 11/19/2022 7:00 PM, Christian König wrote: >>>>      Yes, exactly that's the idea. >>>> >>>>      The only alternatives I can see would be to either move >>>> allocating >>>>      the >>>>      file and so completing the dma_buf initialization last again >>>> or just >>>>      ignore errors from sysfs. >>>> >>>>      > If we still want to avoid calling >>>> dmabuf->ops->release(dmabuf) in >>>>      > dma_buf_release like the comment says I guess we could use >>>>      sysfs_entry >>>>      > and ERR_PTR to flag that, otherwise it looks like we'd need >>>> a bit >>>>      > somewhere. >>>> >>>>      No, this should be dropped as far as I can see. The sysfs cleanup >>>>      code >>>>      looks like it can handle not initialized kobj pointers. >>>> >>>> >>>> Yeah there is also the null check in dma_buf_stats_teardown() that >>>> would prevent it from running, but I understood the comment to be >>>> referring to the release() dma_buf_ops call into the exporter which >>>> comes right after the teardown call. That looks like it's preventing >>>> the fput task work calling back into the exporter after the exporter >>>> already got an error from dma_buf_export(). Otherwise the exporter >>>> sees a release() for a buffer that it doesn't know about / thinks >>>> shouldn't exist. So I could imagine an exporter trying to double free: >>>> once for the failed dma_buf_export() call, and again when the >>>> release() op is called later. >>> >>> Oh, very good point as well. Yeah, then creating the file should >>> probably come last. >>> >> @Gaosheng: Could you please make these changes or you let me to do? >> >>> Regards, >>> Christian. >> .