From: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
To: Jeffrey Hugo <jhugo@codeaurora.org>
Cc: hemantk@codeaurora.org, bbhatt@codeaurora.org,
linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] bus: mhi: core: Check state before processing power_down
Date: Wed, 24 Feb 2021 21:28:48 +0530 [thread overview]
Message-ID: <20210224155848.GX27945@work> (raw)
In-Reply-To: <c67dac35-49d8-212f-824d-5ba52513ac8a@codeaurora.org>
On Wed, Feb 24, 2021 at 08:14:53AM -0700, Jeffrey Hugo wrote:
> On 2/24/2021 2:55 AM, Manivannan Sadhasivam wrote:
> > On Wed, Feb 17, 2021 at 09:43:31AM -0700, Jeffrey Hugo wrote:
> > > We cannot process a power_down if the power state is DISABLED. There is
> > > no valid mhi_ctxt in that case, so attepting to process the power_down
> > > will likely result in a null pointer dereference. If the power state is
> > > DISABLED, there is nothing to do anyways, so just bail early.
> > >
> > > Signed-off-by: Jeffrey Hugo <jhugo@codeaurora.org>
> > > ---
> > >
> > > v2: Fix subject and tweak the locking to avoid needless lock/unlock/relock
> > >
> > > drivers/bus/mhi/core/pm.c | 9 ++++++++-
> > > 1 file changed, 8 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/bus/mhi/core/pm.c b/drivers/bus/mhi/core/pm.c
> > > index 56ba3ab..47f6621 100644
> > > --- a/drivers/bus/mhi/core/pm.c
> > > +++ b/drivers/bus/mhi/core/pm.c
> > > @@ -1144,6 +1144,7 @@ int mhi_async_power_up(struct mhi_controller *mhi_cntrl)
> > > mhi_deinit_dev_ctxt(mhi_cntrl);
> > > error_dev_ctxt:
> > > + mhi_cntrl->pm_state = MHI_PM_DISABLE;
> > > mutex_unlock(&mhi_cntrl->pm_mutex);
> > > return ret;
> > > @@ -1155,11 +1156,17 @@ void mhi_power_down(struct mhi_controller *mhi_cntrl, bool graceful)
> > > enum mhi_pm_state cur_state, transition_state;
> > > struct device *dev = &mhi_cntrl->mhi_dev->dev;
> > > + mutex_lock(&mhi_cntrl->pm_mutex);
> > > + cur_state = mhi_cntrl->pm_state;
> >
> > As I said in my previous review, you should use pm_lock for reading the
> > pm_state.
>
> You also said on IRC that is a refactor of the entire driver, and not a
> blocker for this fix. Based on that, I intrepreted your comments as nothing
> needed to be done regarding the locking, so I'm confused by this comment.
>
> I'm not entirely sure what you want since I feel like you are giving
> conflicting direction, but I'm guessing you want the lock of the pm_lock to
> be moved up to just under the mutex lock then?
>
Yes, that's what my intention is. Sorry if I confused you.
Thanks,
Mani
> --
> Jeffrey Hugo
> Qualcomm Technologies, Inc. is a member of the
> Code Aurora Forum, a Linux Foundation Collaborative Project.
prev parent reply other threads:[~2021-02-24 16:14 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-17 16:43 [PATCH v2] bus: mhi: core: Check state before processing power_down Jeffrey Hugo
2021-02-24 9:55 ` Manivannan Sadhasivam
2021-02-24 15:14 ` Jeffrey Hugo
2021-02-24 15:58 ` Manivannan Sadhasivam [this message]
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