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From: Jinpu Wang <jinpu.wang@cloud.ionos.com>
To: Leon Romanovsky <leon@kernel.org>
Cc: 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>,
	Jason Gunthorpe <jgg@ziepe.ca>,
	Danil Kipnis <danil.kipnis@cloud.ionos.com>,
	Roman Penyaev <rpenyaev@suse.de>
Subject: Re: [PATCH v7 06/25] RDMA/rtrs: client: main functionality
Date: Mon, 20 Jan 2020 12:24:21 +0100
Message-ID: <CAMGffE=22zvvOFJpzyJPOLQFwA+9oMoxZSj=FAZV6RBonwJaEA@mail.gmail.com> (raw)
In-Reply-To: <20200118101254.GD18467@unreal>

> > > > > > +static bool __rtrs_clt_change_state(struct rtrs_clt_sess *sess,
> > > > > > +                                  enum rtrs_clt_state new_state)
> > > > > > +{
> > > > > > +     enum rtrs_clt_state old_state;
> > > > > > +     bool changed = false;
> > > > > > +
> > > > > > +     lockdep_assert_held(&sess->state_wq.lock);
> > > > > > +
> > > > > > +     old_state = sess->state;
> > > > > > +     switch (new_state) {
> > > > > > +     case RTRS_CLT_CONNECTING:
> > > > > > +             switch (old_state) {
> > > > >
> > > > > Double switch is better to be avoided.
> > > > what's the better way to do it?
> > >
> > > Rewrite function to be more readable.
> > Frankly I think it's easy to read, depends on old_state change to new state.
> > see also scsi_device_set_state
>
> If you so in favor of switch inside switch, at lest do it properly.
>
> The scsi_device_set_state() function implements success-oriented
> approach and has very clear state machine without distraction and
> extra variables like changed/not_changed. You have completely
> opposite implementation to scsi_device_set_state().
Thanks for reviewing our code during the weekend, I respect the effort.

The reason we have "changed" variable is only when the state changed
as expected,
the caller will do further action like reconnect or close the session.

I will add kernel-doc around the function to make it more clear.

Thanks Leon

  reply index

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-16 12:58 [PATCH v7 00/25] RTRS (former IBTRS) RDMA Transport Library and RNBD (former IBNBD) RDMA Network Block Device Jack Wang
2020-01-16 12:58 ` [PATCH v7 01/25] sysfs: export sysfs_remove_file_self() Jack Wang
2020-01-16 12:58 ` [PATCH v7 02/25] RDMA/rtrs: public interface header to establish RDMA connections Jack Wang
2020-01-16 12:58 ` [PATCH v7 03/25] RDMA/rtrs: private headers with rtrs protocol structs and helpers Jack Wang
2020-01-16 12:58 ` [PATCH v7 04/25] RDMA/rtrs: core: lib functions shared between client and server modules Jack Wang
2020-01-19 14:48   ` Leon Romanovsky
2020-01-20 11:32     ` Jinpu Wang
2020-01-20 13:30       ` Leon Romanovsky
2020-01-20 14:08         ` Jinpu Wang
2020-01-16 12:58 ` [PATCH v7 05/25] RDMA/rtrs: client: private header with client structs and functions Jack Wang
2020-01-16 12:58 ` [PATCH v7 06/25] RDMA/rtrs: client: main functionality Jack Wang
2020-01-16 14:53   ` Leon Romanovsky
2020-01-16 15:43     ` Jinpu Wang
2020-01-16 15:53       ` Jason Gunthorpe
2020-01-16 16:48         ` Jinpu Wang
2020-01-16 15:58       ` Leon Romanovsky
2020-01-16 16:24         ` Jinpu Wang
2020-01-18 10:12           ` Leon Romanovsky
2020-01-20 11:24             ` Jinpu Wang [this message]
2020-01-16 12:58 ` [PATCH v7 07/25] RDMA/rtrs: client: statistics functions Jack Wang
2020-01-16 12:58 ` [PATCH v7 08/25] RDMA/rtrs: client: sysfs interface functions Jack Wang
2020-01-16 12:58 ` [PATCH v7 09/25] RDMA/rtrs: server: private header with server structs and functions Jack Wang
2020-01-16 12:59 ` [PATCH v7 10/25] RDMA/rtrs: server: main functionality Jack Wang
2020-01-16 12:59 ` [PATCH v7 11/25] RDMA/rtrs: server: statistics functions Jack Wang
2020-01-16 12:59 ` [PATCH v7 12/25] RDMA/rtrs: server: sysfs interface functions Jack Wang
2020-01-16 12:59 ` [PATCH v7 13/25] RDMA/rtrs: include client and server modules into kernel compilation Jack Wang
2020-01-16 12:59 ` [PATCH v7 14/25] RDMA/rtrs: a bit of documentation Jack Wang
2020-01-16 12:59 ` [PATCH v7 15/25] block/rnbd: private headers with rnbd protocol structs and helpers Jack Wang
2020-01-16 12:59 ` [PATCH v7 16/25] block/rnbd: client: private header with client structs and functions Jack Wang
2020-01-16 12:59 ` [PATCH v7 17/25] block/rnbd: client: main functionality Jack Wang
2020-01-20 13:48   ` Leon Romanovsky
2020-01-20 17:30     ` Jinpu Wang
2020-01-22 12:31       ` Leon Romanovsky
2020-01-22 12:52         ` Jinpu Wang
2020-01-22 11:22     ` Jinpu Wang
2020-01-22 12:25       ` Leon Romanovsky
2020-01-22 13:12         ` Jinpu Wang
2020-01-22 14:07           ` Leon Romanovsky
2020-01-22 14:18             ` Jinpu Wang
2020-01-16 12:59 ` [PATCH v7 18/25] block/rnbd: client: sysfs interface functions Jack Wang
2020-01-16 12:59 ` [PATCH v7 19/25] block/rnbd: server: private header with server structs and functions Jack Wang
2020-01-16 12:59 ` [PATCH v7 20/25] block/rnbd: server: main functionality Jack Wang
2020-01-16 12:59 ` [PATCH v7 21/25] block/rnbd: server: functionality for IO submission to file or block dev Jack Wang
2020-01-16 12:59 ` [PATCH v7 22/25] block/rnbd: server: sysfs interface functions Jack Wang
2020-01-16 12:59 ` [PATCH v7 23/25] block/rnbd: include client and server modules into kernel compilation Jack Wang
2020-01-16 14:40   ` Leon Romanovsky
2020-01-16 14:54     ` Jinpu Wang
2020-01-16 15:59       ` Leon Romanovsky
2020-01-16 16:53         ` Jinpu Wang
2020-01-16 12:59 ` [PATCH v7 24/25] block/rnbd: a bit of documentation Jack Wang
2020-01-16 12:59 ` [PATCH v7 25/25] MAINTAINERS: Add maintainers for RNBD/RTRS modules Jack Wang

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