From: Ulf Hansson <ulf.hansson@linaro.org>
To: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: rjw@rjwysocki.net, heiko@sntech.de, lukasz.luba@arm.com,
linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org,
Daniel Lezcano <daniel.lezcano@kernel.org>,
"Rafael J. Wysocki" <rafael@kernel.org>
Subject: Re: [PATCH v1 3/7] powercap/dtpm: Fixup kfree for virtual node
Date: Thu, 17 Feb 2022 14:17:13 +0100 [thread overview]
Message-ID: <CAPDyKFr8Ycr2cbiD5MM9FSPc1qea+Yp9=cottcGAo7HmFR9Eaw@mail.gmail.com> (raw)
In-Reply-To: <e44b9c4b-2ac4-4ea4-c771-bde13943af5f@linaro.org>
On Wed, 16 Feb 2022 at 19:10, Daniel Lezcano <daniel.lezcano@linaro.org> wrote:
>
> On 16/02/2022 17:22, Ulf Hansson wrote:
> > On Sun, 30 Jan 2022 at 22:02, Daniel Lezcano <daniel.lezcano@linaro.org> wrote:
> >>
> >> When the node is virtual there is no release function associated which
> >> can free the memory.
> >>
> >> Free the memory when no 'ops' exists.
> >>
> >> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
> >> ---
> >> drivers/powercap/dtpm.c | 4 ++--
> >> 1 file changed, 2 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/drivers/powercap/dtpm.c b/drivers/powercap/dtpm.c
> >> index 0b0121c37a1b..7bddd25a6767 100644
> >> --- a/drivers/powercap/dtpm.c
> >> +++ b/drivers/powercap/dtpm.c
> >> @@ -181,12 +181,12 @@ int dtpm_release_zone(struct powercap_zone *pcz)
> >>
> >> if (dtpm->ops)
> >> dtpm->ops->release(dtpm);
> >> + else
> >> + kfree(dtpm);
> >>
> >
> > This doesn't look correct. Below you check dtpm against "root", which
> > may be after its memory has been freed.
> >
> > If the ->release() function should be responsible for freeing the
> > dtpm, it needs to be called after the check below.
>
> It is harmless, 'root' is not dereferenced but used as an ID
>
> Moreover, in the patch 5/7 it is moved out this function.
Right. It just looks a bit odd here.
>
>
> >> if (root == dtpm)
> >> root = NULL;
> >>
> >> - kfree(dtpm);
So then why doesn't this kfree do the job already?
kfree(NULL) works fine, if dtpm->ops->release(dtpm) already freed the data.
> >> -
> >> return 0;
> >> }
> >>
Kind regards
Uffe
next prev parent reply other threads:[~2022-02-17 13:17 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-30 21:02 [PATCH v1 1/7] powercap/dtpm: Change locking scheme Daniel Lezcano
2022-01-30 21:02 ` [PATCH v1 2/7] powercap/dtpm_cpu: Reset per_cpu variable in the release function Daniel Lezcano
2022-02-16 16:24 ` Ulf Hansson
2022-01-30 21:02 ` [PATCH v1 3/7] powercap/dtpm: Fixup kfree for virtual node Daniel Lezcano
2022-02-16 16:22 ` Ulf Hansson
2022-02-16 18:10 ` Daniel Lezcano
2022-02-17 13:17 ` Ulf Hansson [this message]
2022-02-17 13:54 ` Daniel Lezcano
2022-02-17 15:45 ` Ulf Hansson
2022-02-18 13:17 ` Daniel Lezcano
2022-02-22 15:55 ` Ulf Hansson
2022-02-22 15:59 ` Daniel Lezcano
2022-01-30 21:02 ` [PATCH v1 4/7] powercap/dtpm: Destroy hierarchy function Daniel Lezcano
2022-02-16 16:31 ` Ulf Hansson
2022-02-16 19:25 ` Daniel Lezcano
2022-02-17 13:12 ` Ulf Hansson
2022-02-17 13:17 ` Ulf Hansson
2022-01-30 21:02 ` [PATCH v1 5/7] powercap/dtpm: Move the 'root' reset place Daniel Lezcano
2022-02-17 13:19 ` Ulf Hansson
2022-01-30 21:02 ` [PATCH v1 6/7] powercap/dtpm/dtpm_cpu: Add exit function Daniel Lezcano
2022-02-17 13:20 ` Ulf Hansson
2022-01-30 21:02 ` [PATCH v1 7/7] dtpm/soc/rk3399: Add the ability to unload the module Daniel Lezcano
2022-02-17 13:21 ` Ulf Hansson
2022-02-16 16:24 ` [PATCH v1 1/7] powercap/dtpm: Change locking scheme Ulf Hansson
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