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[91.78.208.152]) by smtp.googlemail.com with ESMTPSA id q16sm4296014ljj.23.2020.04.30.07.13.37 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 30 Apr 2020 07:13:38 -0700 (PDT) Subject: Re: [RFC PATCH v11 6/9] media: tegra: Add Tegra210 Video input driver From: Dmitry Osipenko To: Sowjanya Komatineni , thierry.reding@gmail.com, jonathanh@nvidia.com, frankc@nvidia.com, hverkuil@xs4all.nl, sakari.ailus@iki.fi, helen.koike@collabora.com Cc: sboyd@kernel.org, linux-media@vger.kernel.org, devicetree@vger.kernel.org, linux-clk@vger.kernel.org, linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org References: <1588197606-32124-1-git-send-email-skomatineni@nvidia.com> <1588197606-32124-7-git-send-email-skomatineni@nvidia.com> <4da289e6-036f-853b-beb4-379d6462adb0@gmail.com> Message-ID: Date: Thu, 30 Apr 2020 17:13:37 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <4da289e6-036f-853b-beb4-379d6462adb0@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 30.04.2020 17:02, Dmitry Osipenko пишет: > 30.04.2020 16:56, Dmitry Osipenko пишет: >> 30.04.2020 01:00, Sowjanya Komatineni пишет: >>> +static int chan_capture_kthread_finish(void *data) >>> +{ >>> + struct tegra_vi_channel *chan = data; >>> + struct tegra_channel_buffer *buf; >>> + >>> + set_freezable(); >>> + >>> + while (1) { >>> + try_to_freeze(); >> >> I guess it won't be great to freeze in the middle of a capture process, so: >> if (list_empty(&chan->done)) >> try_to_freeze(); > > And here should be some locking protection in order not race with the > chan_capture_kthread_start because kthread_finish could freeze before > kthread_start. Or maybe both start / finish threads should simply be allowed to freeze only when both capture and done lists are empty. if (list_empty(&chan->capture) && list_empty(&chan->done)) try_to_freeze();