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Date:   Sat, 26 Nov 2022 04:43:54 +0700
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Subject: Re: [PATCH v5 2/3] io_uring: add api to set / get napi configuration.
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To:     Facebook Kernel Team <kernel-team@fb.com>,
        Stefan Roesch <shr@devkernel.io>
Cc:     Jens Axboe <axboe@kernel.dk>,
        Olivier Langlois <olivier@trillion01.com>,
        Jakub Kicinski <kuba@kernel.org>,
        netdev Mailing List <netdev@vger.kernel.org>,
        io-uring Mailing List <io-uring@vger.kernel.org>
References: <20221121191437.996297-1-shr@devkernel.io>
 <20221121191437.996297-3-shr@devkernel.io>
From:   Ammar Faizi <ammarfaizi2@gnuweeb.org>
In-Reply-To: <20221121191437.996297-3-shr@devkernel.io>
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On 11/22/22 2:14 AM, Stefan Roesch wrote:
> +static int io_unregister_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,
> +	};
> +
> +	if (copy_to_user(arg, &curr, sizeof(curr)))
> +		return -EFAULT;
> +
> +	WRITE_ONCE(ctx->napi_busy_poll_to, 0);
> +	return 0;
> +#else
> +	return -EINVAL;
> +#endif
> +}
> +
I suggest allowing users to pass a NULL as the arg in case they
don't want to care about the old values.

Something like:

    io_uring_unregister_napi(ring, NULL);

What do you think?

-- 
Ammar Faizi