Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Subject: Re: [PATCH v6 46/52] opp: Put interconnect paths outside of
 opp_table_lock
To:     Viresh Kumar <viresh.kumar@linaro.org>
Cc:     Thierry Reding <thierry.reding@gmail.com>,
        Jonathan Hunter <jonathanh@nvidia.com>,
        Georgi Djakov <georgi.djakov@linaro.org>,
        Rob Herring <robh+dt@kernel.org>,
        Michael Turquette <mturquette@baylibre.com>,
        Stephen Boyd <sboyd@kernel.org>,
        Peter De Schrijver <pdeschrijver@nvidia.com>,
        MyungJoo Ham <myungjoo.ham@samsung.com>,
        Kyungmin Park <kyungmin.park@samsung.com>,
        Chanwoo Choi <cw00.choi@samsung.com>,
        Mikko Perttunen <cyndis@kapsi.fi>,
        Viresh Kumar <vireshk@kernel.org>,
        Peter Geis <pgwipeout@gmail.com>,
        Nicolas Chauvet <kwizart@gmail.com>,
        Krzysztof Kozlowski <krzk@kernel.org>,
        linux-tegra@vger.kernel.org, linux-pm@vger.kernel.org,
        linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
        devicetree@vger.kernel.org
References: <20201025221735.3062-1-digetx@gmail.com>
 <20201025221735.3062-47-digetx@gmail.com>
 <20201027051013.5gr4s3wuuwxsd7ax@vireshk-i7>
From:   Dmitry Osipenko <digetx@gmail.com>
Message-ID: <44169d24-4afc-5388-788f-d1e8263fc627@gmail.com>
Date:   Tue, 27 Oct 2020 23:26:16 +0300
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101
 Thunderbird/68.10.0
MIME-Version: 1.0
In-Reply-To: <20201027051013.5gr4s3wuuwxsd7ax@vireshk-i7>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 8bit
Precedence: bulk

27.10.2020 08:10, Viresh Kumar пишет:
> On 26-10-20, 01:17, Dmitry Osipenko wrote:
>> This patch fixes lockup which happens when OPP table is released if
>> interconnect provider uses OPP in the icc_provider->set() callback
>> and bandwidth of the ICC path is set to 0 by the ICC core when path
>> is released. The icc_put() doesn't need the opp_table_lock protection,
>> hence let's move it outside of the lock in order to resolve the problem.
>>
>> In particular this fixes tegra-devfreq driver lockup on trying to unload
>> the driver module. The devfreq driver uses OPP-bandwidth API and its ICC
>> provider also uses OPP for DVFS, hence they both take same opp_table_lock
>> when OPP table of the devfreq is released.
>>
>> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
>> ---
...
> 
> Never make such _fixes_ part of such a big patchset. Always send them
> separately.

Perhaps it's not obvious from the commit description that this patch
doesn't fix any known problems of the current mainline kernel and it's
needed only for the new patches.

> Having said that, I already have a patch with me which shall fix it for you as
> well:

I see that yours fix is already applied, thanks!