Re: [PATCH 1/3] nvme: 002: fix nvmet pass data with loop

[Minwoo Im <minwoo.im.dev@gmail.com>]

> Isn't this unsigned ? as pointed out by Keith ?
>
> $ cat a.c
> int main(void)
> {
>         return -1;
> }
> $ gcc a.c -o a
> $ ./a
> $ echo $?
> 255
>
> May be I'm missing something here ?

I meant that the program returns in a signed value, but it's going to be
parsed in 8bits which is unix style, I think.  Sorry for being unclear.
That's not enough to hold nvme status value at all.

> >
> > If you have any idea about it, Please let me know.  By the way, I really do
> > agree with what you mentioned about the return value.  If it's possible,
> > I would like to too :)
>
> How about we instead of returning the NVMe Status we map the NVMe Status
> of the program to the error code and in-turn return that error code ?
>
> The above is true only when command is successfully submitted from the
> program i.e. no errno is set by any library calls and failed in the
> completion queue entry with NVMe Status != NVME_SC_SUCCESS.
>
> For your reference In kernel we already do this detailed mapping where :-
>
> 1. Please refer to the drivers/nvme/target/core.c file where we map the
> errno_to_nvme_status(), the reverse mapping of that function can be done
> with nvme_status_to_errno(). Of course you will have to add more cases
> and do in-detail reverse error mapping from NVMe status to errno and
> return that errno.
> 2. nvme_error_status() we map NVMe Status to block layer status.
> 3. blk_status_to_errno() we map the block layer status to the errno.
>
> With the help of 1, 2 and 3 you can reverse map the NVMe Status to errno
> and add that mapper function for nvme-cli which will be consistent with
> the kernel NVMe status to errno mapping.
>
> Now you might find some cases where you cannot map all the status codes
> to errno and for those default cases you may end up using something like
> EIO, this is still better way than having to return 0.

Got your point. To make this discussion short, I think we need to make it
in nvme-cli first.  Let me have a discussion on the following link:
https://github.com/linux-nvme/nvme-cli/pull/492

Thanks,