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From: Ammar Faizi <[email protected]>
To: Jens Axboe <[email protected]>
Cc: Stefan Roesch <[email protected]>,
	Facebook Kernel Team <[email protected]>,
	Olivier Langlois <[email protected]>,
	netdev Mailing List <[email protected]>,
	io-uring Mailing List <[email protected]>,
	Jakub Kicinski <[email protected]>
Subject: Re: [PATCH v5 2/3] io_uring: add api to set / get napi configuration.
Date: Tue, 22 Nov 2022 20:13:43 +0700	[thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>

On 11/22/22 2:46 AM, Jens Axboe wrote:
> On 11/21/22 12:14?PM, 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
>> +}
> 
> Should probably check resv/pad here as well, maybe even the
> 'busy_poll_to' being zero?

Jens, this function doesn't read from __user memory, it writes to
__user memory.

@curr.resv and @curr.pad are on the kernel's stack. Both are already
implicitly initialized to zero by the partial struct initializer.

-- 
Ammar Faizi


  reply	other threads:[~2022-11-22 13:14 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-11-21 19:14 [PATCH v5 0/3] io_uring: add napi busy polling support Stefan Roesch
2022-11-21 19:14 ` [PATCH v5 1/3] " Stefan Roesch
2022-11-21 19:45   ` Jens Axboe
2022-11-21 23:59     ` Jens Axboe
2022-11-21 19:14 ` [PATCH v5 2/3] io_uring: add api to set / get napi configuration Stefan Roesch
2022-11-21 19:46   ` Jens Axboe
2022-11-22 13:13     ` Ammar Faizi [this message]
2022-11-22 13:19       ` Jens Axboe
2022-11-25 21:43   ` Ammar Faizi
2022-11-28 20:22     ` Stefan Roesch
2022-11-21 19:14 ` [PATCH v5 3/3] io_uring: add api to set napi prefer busy poll Stefan Roesch

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