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@xxxxxxxxxxxx> > > > > 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@xxxxxxxxxxxx> > > 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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