Re: [PATCH 1/2] io_uring/uring_cmd: cleanup struct io_uring_cmd_data layout

[Jens Axboe <axboe@kernel.dk>]

On 1/23/25 7:38 AM, Pavel Begunkov wrote:
> On 1/23/25 14:21, Jens Axboe wrote:
>> A few spots in uring_cmd assume that the SQEs copied are always at the
>> start of the structure, and hence mix req->async_data and the struct
>> itself.
>>
>> Clean that up and use the proper indices.
>>
>> Signed-off-by: Jens Axboe <axboe@kernel.dk>
>> ---
>>   io_uring/uring_cmd.c | 6 +++---
>>   1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c
>> index 3993c9339ac7..6a63ec4b5445 100644
>> --- a/io_uring/uring_cmd.c
>> +++ b/io_uring/uring_cmd.c
>> @@ -192,8 +192,8 @@ static int io_uring_cmd_prep_setup(struct io_kiocb *req,
>>           return 0;
>>       }
>>   -    memcpy(req->async_data, sqe, uring_sqe_size(req->ctx));
>> -    ioucmd->sqe = req->async_data;
>> +    memcpy(cache->sqes, sqe, uring_sqe_size(req->ctx));
>> +    ioucmd->sqe = cache->sqes;
>>       return 0;
>>   }
>>   @@ -260,7 +260,7 @@ int io_uring_cmd(struct io_kiocb *req, unsigned int issue_flags)
>>           struct io_uring_cmd_data *cache = req->async_data;
>>             if (ioucmd->sqe != (void *) cache)
>> -            memcpy(cache, ioucmd->sqe, uring_sqe_size(req->ctx));
>> +            memcpy(cache->sqes, ioucmd->sqe, uring_sqe_size(req->ctx));
> 
> 3347fa658a1b ("io_uring/cmd: add per-op data to struct io_uring_cmd_data")
> 
> IIUC the patch above is queued for 6.14, and with that this patch
> looks like a fix? At least it feels pretty dangerous without.

It's not a fix, the sqes are first in the struct even with that patch.
So I'd consider it a cleanup. In any case, targeting 6.14 for these
alloc cache cleanups as it got introduced there as well.

-- 
Jens Axboe