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Message-ID: <e039827d-ab7b-1791-d06c-a52ebc949de8@gmail.com>
Date: Mon, 4 Apr 2022 09:20:00 +0100
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Subject: Re: [RFC 3/5] io_uring: add infra and support for IORING_OP_URING_CMD
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To: Christoph Hellwig <hch@lst.de>, Kanchan Joshi <joshi.k@samsung.com>
Cc: axboe@kernel.dk, io-uring@vger.kernel.org,
linux-nvme@lists.infradead.org, ming.lei@redhat.com,
mcgrof@kernel.org, pankydev8@gmail.com, javier@javigon.com,
joshiiitr@gmail.com, anuj20.g@samsung.com
References: <20220401110310.611869-1-joshi.k@samsung.com>
<CGME20220401110834epcas5p4d1e5e8d1beb1a6205d670bbcb932bf77@epcas5p4.samsung.com>
<20220401110310.611869-4-joshi.k@samsung.com> <20220404071656.GC444@lst.de>
From: Pavel Begunkov <asml.silence@gmail.com>
In-Reply-To: <20220404071656.GC444@lst.de>
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On 4/4/22 08:16, Christoph Hellwig wrote:
[...]
>> +static void io_uring_cmd_work(struct io_kiocb *req, bool *locked)
>> +{
>> + req->uring_cmd.driver_cb(&req->uring_cmd);
>> +}
>> +
>> +void io_uring_cmd_complete_in_task(struct io_uring_cmd *ioucmd,
>> + void (*driver_cb)(struct io_uring_cmd *))
>> +{
>> + struct io_kiocb *req = container_of(ioucmd, struct io_kiocb, uring_cmd);
>> +
>> + req->uring_cmd.driver_cb = driver_cb;
>> + req->io_task_work.func = io_uring_cmd_work;
>> + io_req_task_work_add(req, !!(req->ctx->flags & IORING_SETUP_SQPOLL));
>> +}
>> +EXPORT_SYMBOL_GPL(io_uring_cmd_complete_in_task);
>
> I'm still not a fund of the double indirect call here. I don't really
> have a good idea yet, but I plan to look into it.
I haven't familiarised myself with the series properly, but if it's about
driver_cb, we can expose struct io_kiocb and io_req_task_work_add() so
the lower layers can implement their own io_task_work.func. Hopefully, it
won't be inventively abused...
# io_uring.h
static inline struct io_uring_cmd *io_req_to_ucmd(struct io_kiocb *req)
{
return container_of();
}
typedef void (*io_tw_cb_t)(struct io_kiocb *req, bool *locked);
static inline void io_cmd_tw_add(struct io_uring_cmd *ioucmd, io_tw_cb_t foo)
{
struct io_kiocb *req = container_of(ioucmb...);
req->io_task_work.func = foo;
io_req_task_work_add();
}
>> static void io_req_task_queue_fail(struct io_kiocb *req, int ret)
>
> Also it would be great to not add it between io_req_task_queue_fail and
> the callback set by it.
>
>> +void io_uring_cmd_done(struct io_uring_cmd *ioucmd, ssize_t ret)
>> +{
>> + struct io_kiocb *req = container_of(ioucmd, struct io_kiocb, uring_cmd);
>> +
>> + if (ret < 0)
>> + req_set_fail(req);
>> + io_req_complete(req, ret);
>> +}
>> +EXPORT_SYMBOL_GPL(io_uring_cmd_done);
>
> It seems like all callers of io_req_complete actually call req_set_fail
> on failure. So maybe it would be nice pre-cleanup to handle the
> req_set_fail call from ĩo_req_complete?
Interpretation of the result is different, e.g. io_tee(), that was the
reason it was left in the callers.
[...]
>> @@ -60,7 +62,10 @@ struct io_uring_sqe {
>> __s32 splice_fd_in;
>> __u32 file_index;
>> };
>> - __u64 __pad2[2];
>> + union {
>> + __u64 __pad2[2];
>> + __u64 cmd;
>> + };
>
> Can someone explain these changes to me a little more?
not required indeed, just
- __u64 __pad2[2];
+ __u64 cmd;
+ __u64 __pad2;
--
Pavel Begunkov