From: Jens Axboe <[email protected]>
To: Josh Triplett <[email protected]>,
Pavel Begunkov <[email protected]>
Cc: [email protected], [email protected]
Subject: Re: [PATCHv2] io_uring: Support calling io_uring_register with a registered ring fd
Date: Wed, 15 Feb 2023 10:44:38 -0700 [thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <f2396369e638284586b069dbddffb8c992afba95.1676419314.git.josh@joshtriplett.org>
On 2/14/23 5:42 PM, Josh Triplett wrote:
> Add a new flag IORING_REGISTER_USE_REGISTERED_RING (set via the high bit
> of the opcode) to treat the fd as a registered index rather than a file
> descriptor.
>
> This makes it possible for a library to open an io_uring, register the
> ring fd, close the ring fd, and subsequently use the ring entirely via
> registered index.
This looks pretty straight forward to me, only real question I had
was whether using the top bit of the register opcode for this is the
best choice. But I can't think of better ways to do it, and the space
is definitely big enough to do that, so looks fine to me.
One more comment below:
> + if (use_registered_ring) {
> + /*
> + * Ring fd has been registered via IORING_REGISTER_RING_FDS, we
> + * need only dereference our task private array to find it.
> + */
> + struct io_uring_task *tctx = current->io_uring;
I need to double check if it's guaranteed we always have current->io_uring
assigned here. If the ring is registered we certainly will have it, but
what if someone calls io_uring_register(2) without having a ring setup
upfront?
IOW, I think we need a NULL check here and failing the request at that
point.
--
Jens Axboe
next prev parent reply other threads:[~2023-02-15 17:44 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-15 0:42 [PATCHv2] io_uring: Support calling io_uring_register with a registered ring fd Josh Triplett
2023-02-15 17:44 ` Jens Axboe [this message]
2023-02-15 20:33 ` Josh Triplett
2023-02-15 21:39 ` Jens Axboe
2023-02-16 3:24 ` Jens Axboe
2023-02-16 9:35 ` Dylan Yudaken
2023-02-16 12:05 ` Josh Triplett
2023-02-16 13:10 ` Jens Axboe
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