From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jason Gunthorpe <jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
Subject: Re: [PATCH V2 for-next 7/7] IB/core: Change completion channel to
 use the reworked objects schema
Date: Wed, 29 Mar 2017 16:29:35 -0600
Message-ID: <20170329222935.GB30605@obsidianresearch.com>
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To: Matan Barak <matanb-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org>
Cc: Matan Barak <matanb-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>, Doug Ledford <dledford-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, linux-rdma <linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, Liran Liss <liranl-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>, Sean Hefty <sean.hefty-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>, Leon Romanovsky <leonro-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>, Majd Dibbiny <majd-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>, Tal Alon <talal-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>, Yishai Hadas <yishaih-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>, Ira Weiny <ira.weiny-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>, Haggai Eran <haggaie-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>, Christoph Lameter <cl-vYTEC60ixJUAvxtiuMwx3w@public.gmane.org>
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On Wed, Mar 29, 2017 at 09:21:09PM +0300, Matan Barak wrote:
> On Wed, Mar 29, 2017 at 5:53 PM, Jason Gunthorpe
> <jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org> wrote:
> > On Sun, Mar 19, 2017 at 05:59:05PM +0200, Matan Barak wrote:
> >> +static struct ib_uverbs_completion_event_file *
> >> +ib_uverbs_lookup_comp_file(int fd, struct ib_ucontext *context)
> >> +{
> >> +     struct ib_uobject *uobj = uobj_get_read(uobj_get_type(comp_channel),
> >> +                                             fd, context);
> >> +     struct ib_uobject_file *uobj_file;
> >> +
> >> +     if (IS_ERR(uobj))
> >> +             return (void *)uobj;
> >> +
> >> +     uobj_file = container_of(uobj, struct ib_uobject_file, uobj);
> >> +
> >> +     uverbs_uobject_get(&uobj_file->uobj);
> >> +     uobj_put_read(uobj);
> >
> > That looks odd, isn't uobj == uobj_file->uobj ?
> 
> Yeah, they're essentially the same. The uverbs_uobject_get is intended
> to increase the reference count
> on the returned object. The uobj_put_read is paired with uobj_get_read
> (first line of this function).
> We could change them both to uobj.

I'm confused why you would ever write

uverbs_uobject_get(uobj);
uobj_put_read(uobj);

Maybe drop both lines and just add a comment that the ref from
uobj_get_read moves from the stack to XX

Jason
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