Re: [PATCH v7 06/25] RDMA/rtrs: client: main functionality

From: Jinpu Wang <jinpu.wang@cloud.ionos.com>
To: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Leon Romanovsky <leon@kernel.org>,
	Jack Wang <jinpuwang@gmail.com>,
	linux-block@vger.kernel.org, linux-rdma@vger.kernel.org,
	Jens Axboe <axboe@kernel.dk>,
	Christoph Hellwig <hch@infradead.org>,
	Sagi Grimberg <sagi@grimberg.me>,
	Bart Van Assche <bvanassche@acm.org>,
	Doug Ledford <dledford@redhat.com>,
	Danil Kipnis <danil.kipnis@cloud.ionos.com>,
	Roman Penyaev <rpenyaev@suse.de>
Subject: Re: [PATCH v7 06/25] RDMA/rtrs: client: main functionality
Date: Thu, 16 Jan 2020 17:48:19 +0100	[thread overview]
Message-ID: <CAMGffE=0VX2SwNFBd+EeR3Grh=bSGrkGFqbWkORYoocDbYUy6g@mail.gmail.com> (raw)
In-Reply-To: <20200116155301.GC10759@ziepe.ca>

On Thu, Jan 16, 2020 at 4:53 PM Jason Gunthorpe <jgg@ziepe.ca> wrote:
>
> On Thu, Jan 16, 2020 at 04:43:41PM +0100, Jinpu Wang wrote:
> > > > +             wake_up(&clt->permits_wait);
> > > > +}
> > > > +EXPORT_SYMBOL(rtrs_clt_put_permit);
> > > > +
> > > > +struct rtrs_permit *rtrs_permit_from_pdu(void *pdu)
> > > > +{
> > > > +     return pdu - sizeof(struct rtrs_permit);
> > >
> > > C standard doesn't allow pointer arithmetic on void*.
> > gcc never complains,  searched aournd:
> > https://stackoverflow.com/questions/3523145/pointer-arithmetic-for-void-pointer-in-c
> >
> > You're right, will fix.
>
> The kernel extensively uses a gcc extension treating arithmatic on a
> void * as the same as a u8, you can leave it for kernel code.
>
> But is generally a big question why code is written like that, always
> better to use a struct and container_of
>
> Jason
Thanks, in fact, it's just a function not used, will remove.