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([2a02:810d:15c0:828:bcb8:77e6:8f45:4771]) by smtp.gmail.com with ESMTPSA id l22-20020aa7c3d6000000b00506be898998sm588954edr.29.2023.04.20.03.16.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 20 Apr 2023 03:16:28 -0700 (PDT) From: Krzysztof Kozlowski To: Vinod Koul , Bard Liao , Pierre-Louis Bossart , Sanyog Kale , Andy Gross , Bjorn Andersson , Konrad Dybcio , Liam Girdwood , Mark Brown , Jaroslav Kysela , Takashi Iwai , alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org Subject: [PATCH 5/6] soudnwire: master: protect concurrecnt check for bus->md Date: Thu, 20 Apr 2023 12:16:16 +0200 Message-Id: <20230420101617.142225-6-krzysztof.kozlowski@linaro.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230420101617.142225-1-krzysztof.kozlowski@linaro.org> References: <20230420101617.142225-1-krzysztof.kozlowski@linaro.org> MIME-Version: 1.0 Message-ID-Hash: FXJFBWTADUGQT7KAMYH5K7OBVSF5GNNL X-Message-ID-Hash: FXJFBWTADUGQT7KAMYH5K7OBVSF5GNNL X-MailFrom: krzysztof.kozlowski@linaro.org X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; header-match-alsa-devel.alsa-project.org-0; header-match-alsa-devel.alsa-project.org-1; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: Krzysztof Kozlowski , Patrick Lai X-Mailman-Version: 3.3.8 Precedence: list List-Id: "Alsa-devel mailing list for ALSA developers - http://www.alsa-project.org" Archived-At: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: The Soundwire master controllers might want to check for bus->md initialization to avoid race between early interrupt and finish of sdw_bus_master_add()/sdw_master_device_add(). Such early interrupt can happen if Soundwire devices are not powered off during their probe. Add a store release barrier, so the Soundwire controllers can safely check it in concurrent (e.g. in interrupt) way. Signed-off-by: Krzysztof Kozlowski --- Cc: Patrick Lai --- drivers/soundwire/master.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/drivers/soundwire/master.c b/drivers/soundwire/master.c index 9b05c9e25ebe..d5bf13e7e602 100644 --- a/drivers/soundwire/master.c +++ b/drivers/soundwire/master.c @@ -161,7 +161,12 @@ int sdw_master_device_add(struct sdw_bus *bus, struct device *parent, /* add shortcuts to improve code readability/compactness */ md->bus = bus; bus->dev = &md->dev; - bus->md = md; + /* + * Make sure the contents of md is stored before storing bus->md. + * Paired with new slave attached and slave status interrupts + * on the Soundwire master side. + */ + smp_store_release(&bus->md, md); pm_runtime_set_autosuspend_delay(&bus->md->dev, SDW_MASTER_SUSPEND_DELAY_MS); pm_runtime_use_autosuspend(&bus->md->dev);