linux-kernel - Re: [PATCH 06/10] io_uring: add support for futex wake and wait

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Message-ID: <24a8a74a-e218-6105-ee97-02f60b1523bb@kernel.dk>
Date:   Tue, 25 Jul 2023 14:42:15 -0600
From:   Jens Axboe <axboe@...nel.dk>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     io-uring@...r.kernel.org, linux-kernel@...r.kernel.org,
        andres@...razel.de
Subject: Re: [PATCH 06/10] io_uring: add support for futex wake and wait

On 7/25/23 9:19?AM, Peter Zijlstra wrote:
> On Tue, Jul 25, 2023 at 07:57:28AM -0600, Jens Axboe wrote:
> 
>> Something like the below - totally untested, but just to show what I
>> mean. Will need to get split and folded into the two separate patches.
>> Will test and fold them later today.
>>
>>
>> diff --git a/io_uring/futex.c b/io_uring/futex.c
>> index 4c9f2c841b98..b0f90154d974 100644
>> --- a/io_uring/futex.c
>> +++ b/io_uring/futex.c
>> @@ -168,7 +168,7 @@ bool io_futex_remove_all(struct io_ring_ctx *ctx, struct task_struct *task,
>>  	return found;
>>  }
>>  
>> -int io_futex_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
>> +static int __io_futex_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
>>  {
>>  	struct io_futex *iof = io_kiocb_to_cmd(req, struct io_futex);
>>  	u32 flags;
>> @@ -179,9 +179,6 @@ int io_futex_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
>>  	iof->uaddr = u64_to_user_ptr(READ_ONCE(sqe->addr));
>>  	iof->futex_val = READ_ONCE(sqe->addr2);
>>  	iof->futex_mask = READ_ONCE(sqe->addr3);
>> -	iof->futex_nr = READ_ONCE(sqe->len);
>> -	if (iof->futex_nr && req->opcode != IORING_OP_FUTEX_WAITV)
>> -		return -EINVAL;
>>  
>>  	flags = READ_ONCE(sqe->futex_flags);
>>  	if (flags & ~FUTEX2_MASK)
>> @@ -191,14 +188,36 @@ int io_futex_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
>>  	if (!futex_flags_valid(iof->futex_flags))
>>  		return -EINVAL;
>>  
>> -	if (!futex_validate_input(iof->futex_flags, iof->futex_val) ||
>> -	    !futex_validate_input(iof->futex_flags, iof->futex_mask))
>> +	if (!futex_validate_input(iof->futex_flags, iof->futex_mask))
>>  		return -EINVAL;
>>  
>> -	iof->futexv_owned = 0;
>>  	return 0;
>>  }
> 
> I think you can/should split more into io_futex_prep(), specifically
> waitv should also have zero @val and @mask.

Yep, I'll include that. Updating them now...

-- 
Jens Axboe