netdev - Re: [RFC PATCH v4 2/3] io_uring: add api to set / get napi configuration.

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Message-ID: <qvqw5yf85e91.fsf@dev0134.prn3.facebook.com>
Date:   Mon, 21 Nov 2022 10:55:06 -0800
From:   Stefan Roesch <shr@...kernel.io>
To:     Jens Axboe <axboe@...nel.dk>
Cc:     kernel-team@...com, olivier@...llion01.com, netdev@...r.kernel.org,
        io-uring@...r.kernel.org, kuba@...nel.org
Subject: Re: [RFC PATCH v4 2/3] io_uring: add api to set / get napi
 configuration.


Jens Axboe <axboe@...nel.dk> writes:

> On 11/21/22 10:29?AM, Stefan Roesch wrote:
>> diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
>> index 4f432694cbed..cf0e7cc8ad2e 100644
>> --- a/io_uring/io_uring.c
>> +++ b/io_uring/io_uring.c
>> @@ -4122,6 +4122,48 @@ static __cold int io_register_iowq_max_workers(struct io_ring_ctx *ctx,
>>  	return ret;
>>  }
>>
>> +static int io_register_napi(struct io_ring_ctx *ctx, void __user *arg)
>> +{
>> +#ifdef CONFIG_NET_RX_BUSY_POLL
>> +	const struct io_uring_napi curr = {
>> +		.busy_poll_to = ctx->napi_busy_poll_to,
>> +	};
>> +	struct io_uring_napi *napi;
>> +
>> +	napi = memdup_user(arg, sizeof(*napi));
>> +	if (IS_ERR(napi))
>> +		return PTR_ERR(napi);
>> +
>> +	WRITE_ONCE(ctx->napi_busy_poll_to, napi->busy_poll_to);
>> +
>> +	kfree(napi);
>> +
>> +	if (copy_to_user(arg, &curr, sizeof(curr)))
>> +		return -EFAULT;
>> +
>> +	return 0;
>> +#else
>> +	return -EINVAL;
>> +#endif
>> +}
>
> This should return -EINVAL if any of the padding or reserved fields are
> non-zero. If you don't do that, then it's not expendable in the future.

The next version will have that change.