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Date:   Mon, 3 Aug 2020 17:12:30 +0100
From:   Matthew Wilcox <willy@infradead.org>
To:     Suren Baghdasaryan <surenb@google.com>
Cc:     Kalesh Singh <kaleshsingh@google.com>,
        Jonathan Corbet <corbet@lwn.net>,
        Sumit Semwal <sumit.semwal@linaro.org>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Steven Rostedt <rostedt@goodmis.org>,
        Ingo Molnar <mingo@redhat.com>, linux-doc@vger.kernel.org,
        LKML <linux-kernel@vger.kernel.org>, linux-media@vger.kernel.org,
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        linaro-mm-sig@lists.linaro.org, linux-fsdevel@vger.kernel.org,
        Hridya Valsaraju <hridya@google.com>,
        Ioannis Ilkos <ilkos@google.com>,
        John Stultz <john.stultz@linaro.org>,
        kernel-team <kernel-team@android.com>
Subject: Re: [PATCH 2/2] dmabuf/tracing: Add dma-buf trace events
Message-ID: <20200803161230.GB23808@casper.infradead.org>
References: <20200803144719.3184138-1-kaleshsingh@google.com>
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 <20200803154125.GA23808@casper.infradead.org>
 <CAJuCfpFLikjaoopvt+vGN3W=m9auoK+DLQNgUf-xUbYfC=83Mw@mail.gmail.com>
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On Mon, Aug 03, 2020 at 09:00:00AM -0700, Suren Baghdasaryan wrote:
> On Mon, Aug 3, 2020 at 8:41 AM Matthew Wilcox <willy@infradead.org> wrote:
> >
> > On Mon, Aug 03, 2020 at 02:47:19PM +0000, Kalesh Singh wrote:
> > > +static void dma_buf_fd_install(int fd, struct file *filp)
> > > +{
> > > +     trace_dma_buf_fd_ref_inc(current, filp);
> > > +}
> >
> > You're adding a new file_operation in order to just add a new tracepoint?
> > NACK.
> 
> Hi Matthew,
> The plan is to attach a BPF to this tracepoint in order to track
> dma-buf users. If you feel this is an overkill, what would you suggest
> as an alternative?

I'm sure BPF can attach to fd_install and filter on file->f_ops belonging
to dma_buf, for example.