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From: Bjorn Andersson <bjorn.andersson@linaro.org>
To: rishabhb@codeaurora.org
Cc: Alex Elder <elder@ieee.org>,
	linux-remoteproc@vger.kernel.org, linux-kernel@vger.kernel.org,
	tsoni@codeaurora.org, psodagud@codeaurora.org,
	sidgup@codeaurora.org, linux-remoteproc-owner@vger.kernel.org
Subject: Re: [PATCH v5 1/2] remoteproc: qcom: Add per subsystem SSR notification
Date: Tue, 23 Jun 2020 22:28:01 -0700	[thread overview]
Message-ID: <20200624052801.GB407764@builder.lan> (raw)
In-Reply-To: <cb31dfb50079a1377cf27807a7b2eb3e@codeaurora.org>

On Tue 23 Jun 18:41 PDT 2020, rishabhb@codeaurora.org wrote:

> On 2020-06-23 14:45, Alex Elder wrote:
> > On 6/22/20 8:04 PM, Rishabh Bhatnagar wrote:
> > > Currently there is a single notification chain which is called
> > > whenever any
> > > remoteproc shuts down. This leads to all the listeners being
> > > notified, and
> > > is not an optimal design as kernel drivers might only be interested in
> > > listening to notifications from a particular remoteproc. Create a
> > > global
> > > list of remoteproc notification info data structures. This will hold
> > > the
> > > name and notifier_list information for a particular remoteproc. The
> > > API
> > > to register for notifications will use name argument to retrieve the
> > > notification info data structure and the notifier block will be
> > > added to
> > > that data structure's notification chain. Also move from blocking
> > > notifier
> > > to srcu notifer based implementation to support dynamic notifier head
> > > creation.
> > > 
> > > Signed-off-by: Siddharth Gupta <sidgup@codeaurora.org>
> > > Signed-off-by: Rishabh Bhatnagar <rishabhb@codeaurora.org>
> > 
> > Sorry, a few more comments, but I think your next one will
> > likely be fine.
> > 
> > General:
> > - SSR subsystems are added but never removed.  Note that
> >   "qcom_common.o" can be built as a module, and if that
> >   module were ever removed, memory allocated for these
> >   subsystems would be leaked.
> Hi Alex,
> Thank you for reviewing this patchset quickly. This point was
> brought up by Bjorn and it was decided that I will push another patch on
> top in which I'll do the cleanup during module exit.
> > - Will a remoteproc subdev (and in particular, an SSR subdev)
> >   ever be removed?  What happens to entities that have
> >   registered for SSR notifications in that case?
> In practice it should never be removed. If it is clients will
> never get notification about subsystem shutdown/powerup.

Given that clients make direct function calls into qcom_common.ko,
qcom_common.ko would not be possible to rmmod until all clients has been
rmmod'ed. As such there shouldn't be any remaining listeners, or
subdevices, when this happens.

Regards,
Bjorn

  reply	other threads:[~2020-06-24  5:30 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-23  1:04 [PATCH v5 0/2] Extend SSR notifications framework Rishabh Bhatnagar
2020-06-23  1:04 ` [PATCH v5 1/2] remoteproc: qcom: Add per subsystem SSR notification Rishabh Bhatnagar
2020-06-23 21:45   ` Alex Elder
2020-06-24  1:41     ` rishabhb
2020-06-24  5:28       ` Bjorn Andersson [this message]
2020-06-23  1:04 ` [PATCH v5 2/2] remoteproc: qcom: Add notification types to SSR Rishabh Bhatnagar
2020-06-23 21:45   ` Alex Elder

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