From: Leon Romanovsky <leon@kernel•org>
To: Jason Gunthorpe <jgg@mellanox•com>
Cc: Doug Ledford <dledford@redhat•com>,
RDMA mailing list <linux-rdma@vger•kernel.org>,
linux-s390@vger•kernel.org, Ursula Braun <ubraun@linux•ibm.com>,
"David S. Miller" <davem@davemloft•net>,
netdev@vger•kernel.org,
Selvin Xavier <selvin.xavier@broadcom•com>,
Steve Wise <swise@chelsio•com>, Lijun Ou <oulijun@huawei•com>,
Shiraz Saleem <shiraz.saleem@intel•com>,
Ariel Elior <Ariel.Elior@cavium•com>,
Christian Benvenuti <benve@cisco•com>,
Adit Ranadive <aditr@vmware•com>,
Dennis Dalessandro <dennis.dalessandro@intel•com>
Subject: Re: [PATCH rdma-next 1/5] RDMA/core: Provide getter and setter to access IB device name
Date: Thu, 20 Sep 2018 19:40:39 +0300 [thread overview]
Message-ID: <20180920164039.GM3519@mtr-leonro.mtl.com> (raw)
In-Reply-To: <20180920151541.GC30219@mellanox.com>
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On Thu, Sep 20, 2018 at 09:15:41AM -0600, Jason Gunthorpe wrote:
> On Thu, Sep 20, 2018 at 02:21:58PM +0300, Leon Romanovsky wrote:
> > From: Leon Romanovsky <leonro@mellanox•com>
> >
> > Prepare IB device name field to rename operation by ensuring that all
> > accesses to it are protected with lock and users don't see part of name.
>
> Oh dear, no, that isn't going to work, there is too much stuff using
> dev_name.. Did you read the comment on device_rename??
>
> https://elixir.bootlin.com/linux/v4.19-rc4/source/drivers/base/core.c#L2715
Yes, I read, it was mentioned in the cover letter.
>
> > The protection is done with global device_lock because it is used in
> > allocation and deallocation phases. At this stage, this lock is not
> > busy and easily can be moved to be per-device, once it will be needed.
> >
> > Signed-off-by: Leon Romanovsky <leonro@mellanox•com>
> > drivers/infiniband/core/device.c | 24 +++++++++++++++++++++++-
> > include/rdma/ib_verbs.h | 8 +++++++-
> > 2 files changed, 30 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/infiniband/core/device.c b/drivers/infiniband/core/device.c
> > index 5a680a88aa87..3270cde6d806 100644
> > +++ b/drivers/infiniband/core/device.c
> > @@ -170,6 +170,14 @@ static struct ib_device *__ib_device_get_by_name(const char *name)
> > return NULL;
> > }
> >
> > +void ib_device_get_name(struct ib_device *ibdev, char *name)
> > +{
> > + down_read(&lists_rwsem);
> > + strlcpy(name, ibdev->name, IB_DEVICE_NAME_MAX);
> > + up_read(&lists_rwsem);
> > +}
> > +EXPORT_SYMBOL(ib_device_get_name);
>
> I think we have to follow netdev and just rely on device_rename()
> being 'good enough'.
>
> Switch everything to use dev_name()/etc rather than try and do
> something like this so the responsibility is on the device core to
> keep this working, not us.
>
> Turns out I have a series for that for unrelated reasons..
And what should I do now with this knowledge?
>
> > static int alloc_name(char *name)
> > {
> > unsigned long *inuse;
> > @@ -202,6 +210,21 @@ static int alloc_name(char *name)
> > return 0;
> > }
> >
> > +int ib_device_alloc_name(struct ib_device *ibdev, const char *pattern)
> > +{
> > + int ret = 0;
> > +
> > + mutex_lock(&device_mutex);
> > + strlcpy(ibdev->name, pattern, IB_DEVICE_NAME_MAX);
> > + if (strchr(ibdev->name, '%'))
> > + ret = alloc_name(ibdev->name);
> > +
> > + mutex_unlock(&device_mutex);
> > +
> > + return ret;
> > +}
> > +EXPORT_SYMBOL(ib_device_alloc_name);
>
> Can't call alloc_name() without also adding to the list, this will
> allow duplicates.
I planned to change it in the future by moving to different name scheme
with unique naming.
>
> Jason
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next prev parent reply other threads:[~2018-09-20 22:25 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-20 11:21 [PATCH rdma-next 0/5] IB device rename support Leon Romanovsky
2018-09-20 11:21 ` [PATCH rdma-next 1/5] RDMA/core: Provide getter and setter to access IB device name Leon Romanovsky
2018-09-20 14:32 ` Steve Wise
2018-09-20 15:15 ` Jason Gunthorpe
2018-09-20 16:40 ` Leon Romanovsky [this message]
2018-09-20 16:46 ` Jason Gunthorpe
2018-09-20 11:21 ` [PATCH rdma-next 2/5] net/smc: Use IB device index instead of name Leon Romanovsky
2018-09-20 11:22 ` [PATCH rdma-next 3/5] RDMA: Convert IB drivers to name allocation routine Leon Romanovsky
2018-09-20 11:22 ` [PATCH rdma-next 4/5] RDMA/core: Implement IB device rename function Leon Romanovsky
2018-09-20 11:22 ` [PATCH rdma-next 5/5] RDMA/nldev: Allow IB device rename through RDMA netlink Leon Romanovsky
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