From: Gabriel Krisman Bertazi <krisman@suse.de>
To: Jens Axboe <axboe@kernel.dk>
Cc: io-uring@vger.kernel.org
Subject: Re: [PATCH 1/6] io_uring: expand main struct io_kiocb flags to 64-bits
Date: Thu, 08 Feb 2024 15:52:23 -0500 [thread overview]
Message-ID: <87ttmiu1a0.fsf@mailhost.krisman.be> (raw)
In-Reply-To: <098a9f8c-c5b7-402d-ac35-c48361a9d403@kernel.dk> (Jens Axboe's message of "Thu, 8 Feb 2024 13:22:35 -0700")
Jens Axboe <axboe@kernel.dk> writes:
> On 2/8/24 1:08 PM, Gabriel Krisman Bertazi wrote:
>> Jens Axboe <axboe@kernel.dk> writes:
>>
>>
>>> - TP_printk("ring %p, request %p, user_data 0x%llx, opcode %s, flags 0x%x, %s queue, work %p",
>>> + TP_printk("ring %p, request %p, user_data 0x%llx, opcode %s, flags 0x%lx, %s queue, work %p",
>>> __entry->ctx, __entry->req, __entry->user_data,
>>> - __get_str(op_str),
>>> - __entry->flags, __entry->rw ? "hashed" : "normal", __entry->work)
>>> + __get_str(op_str), (long) __entry->flags,
>>
>> Hi Jens,
>>
>> Minor, but on 32-bit kernel the cast is wrong since
>> sizeof(long)==4. Afaik, io_uring still builds on 32-bit archs.
>>
>> If you use (unsigned long long), it will be 64 bit anywhere.
>
> Ah thanks, I'll make that edit.
>
>>> @@ -2171,7 +2171,8 @@ static int io_init_req(struct io_ring_ctx *ctx, struct io_kiocb *req,
>>> /* req is partially pre-initialised, see io_preinit_req() */
>>> req->opcode = opcode = READ_ONCE(sqe->opcode);
>>> /* same numerical values with corresponding REQ_F_*, safe to copy */
>>> - req->flags = sqe_flags = READ_ONCE(sqe->flags);
>>> + sqe_flags = READ_ONCE(sqe->flags);
>>
>> Did you consider that READ_ONCE won't protect from load tearing the
>> userspace value in 32-bit architectures? It builds silently, though, and
>> I suspect it is mostly fine in the current code, but might become a bug
>> eventually.
>
> sqe->flags is just a byte, so no tearing is possible here. The only
> thing that changed type is req->flags.
You're right, of course. I confused the source of the read with struct
io_kiocb.
--
Gabriel Krisman Bertazi
next prev parent reply other threads:[~2024-02-08 20:52 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-07 17:17 [PATCHSET v2 0/6] Misc cleanups / optimizations Jens Axboe
2024-02-07 17:17 ` [PATCH 1/6] io_uring: expand main struct io_kiocb flags to 64-bits Jens Axboe
2024-02-08 20:08 ` Gabriel Krisman Bertazi
2024-02-08 20:22 ` Jens Axboe
2024-02-08 20:52 ` Gabriel Krisman Bertazi [this message]
2024-02-07 17:17 ` [PATCH 2/6] io_uring/cancel: don't default to setting req->work.cancel_seq Jens Axboe
2024-02-07 17:17 ` [PATCH 3/6] io_uring: add io_file_can_poll() helper Jens Axboe
2024-02-07 17:17 ` [PATCH 4/6] io_uring: mark the need to lock/unlock the ring as unlikely Jens Axboe
2024-02-07 17:17 ` [PATCH 5/6] io_uring: cleanup io_req_complete_post() Jens Axboe
2024-02-07 17:17 ` [PATCH 6/6] io_uring/rw: remove dead file == NULL check Jens Axboe
-- strict thread matches above, loose matches on Subject: below --
2024-02-06 16:22 [PATCHSET next 0/6] Misc cleanups / optimizations Jens Axboe
2024-02-06 16:22 ` [PATCH 1/6] io_uring: expand main struct io_kiocb flags to 64-bits Jens Axboe
2024-02-06 22:58 ` Jens Axboe
2024-02-07 0:43 ` Pavel Begunkov
2024-02-07 2:18 ` Jens Axboe
2024-02-07 3:22 ` Pavel Begunkov
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