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[209.85.220.65]) by mx.google.com with SMTPS id p10sor191538ilg.74.2020.04.22.13.33.06 for (Google Transport Security); Wed, 22 Apr 2020 13:33:06 -0700 (PDT) Received-SPF: pass (google.com: domain of john.stultz@linaro.org designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@linaro.org header.s=google header.b=LEbaRv0d; spf=pass (google.com: domain of john.stultz@linaro.org designates 209.85.220.65 as permitted sender) smtp.mailfrom=john.stultz@linaro.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linaro.org DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=pMZgWl7gaqwxky4xlW6XJbmApvfvRuOxXJn93EkCWVo=; b=LEbaRv0dypc5e5Wc7a84Kw/SbMBDatTaHXbP6iCorD9zGzR1nVNn357pTZEPJbSGH8 DO6J+hGiFfATe4XvgoRwKD/iyt+vOghi0A+9lXjvJKQSSngW7mtkvUKJRtMFXag3XuGi kS1lvfmsj1CAadjzqIYzXXp3EGdkoP2Vb3RtgOpOrpr9uGeAie7EZkyNnSjLFFB/VIX+ cN/PSUP9+7xo5gVqezBN8MHq4yT+hnWXekDCIk3KvZ8RWPcHzzx5WEr2650WPRMUN3Sz od9S/oDQyg22NNcbzi4ErXcO0GuJt9RE4qxMlIr7y0GU4oeBhtj10hVFiTQCWHBjJ7SA 00qA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=pMZgWl7gaqwxky4xlW6XJbmApvfvRuOxXJn93EkCWVo=; b=liLwJx/RK/m8ktPBHpbMzILqQRX6MG3f84aoEWCZ0CznVdxeSQmBt6s2HRWhiELT2t cStW5BzywY9LzOIBElhbdkSjkR2ssNv2zVEAnYd5KkmWThPfD4iz6r6AraSJ4oVbndh3 Eo1Jqs/3IwbuyqNdmdFpYC4/TzApR96b1pchkDG6d2IEkXfHlOrJhamb27TO/Bp3PsoP hdf76TRT5MACUq5fDFD/LBOfSuSLZ7HBOpIiYVa4bSSds0AHHB0PIK/SpdmcvwNKZosl 45Yd9Wt9o7FcriusU0mrJqAgwW527ynYiDsTs36pyW6oZHFCaGIQ2StYL9g5/eA4uMNR VYxA== X-Gm-Message-State: AGi0PubIfyLiJ0SwAnrrSWLOzrki8Bo6pvF7jkgu6Z6P18o2pecaX21x P3N7hPleIz+NdEHr7xSbEBIOabPm X-Google-Smtp-Source: APiQypIk7f8O7AVplXsto40VZokGnKKYUx0F+SKxFkELYuo0ol20r/CNbNqbITXVgN8Ro9fNiSWIaA== X-Received: by 2002:a63:ef4b:: with SMTP id c11mr760981pgk.400.1587587585769; Wed, 22 Apr 2020 13:33:05 -0700 (PDT) Return-Path: Received: from localhost.localdomain ([2601:1c2:680:1319:692:26ff:feda:3a81]) by smtp.gmail.com with ESMTPSA id b24sm360292pfd.175.2020.04.22.13.33.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 22 Apr 2020 13:33:05 -0700 (PDT) From: John Stultz To: lkml Cc: John Stultz , "David S. Miller" , Alexey Kuznetsov , Hideaki YOSHIFUJI , Jakub Kicinski , Greg Kroah-Hartman , "Rafael J . Wysocki" , Rob Herring , Geert Uytterhoeven , Yoshihiro Shimoda , Robin Murphy , Andy Shevchenko , Sudeep Holla , Andy Shevchenko , Naresh Kamboju , Basil Eljuse , Ferry Toth , Arnd Bergmann , Anders Roxell , netdev , linux-pm@vger.kernel.org Subject: [PATCH v3 3/3] driver core: Ensure wait_for_device_probe() waits until the deferred_probe_timeout fires Date: Wed, 22 Apr 2020 20:32:45 +0000 Message-Id: <20200422203245.83244-4-john.stultz@linaro.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200422203245.83244-1-john.stultz@linaro.org> References: <20200422203245.83244-1-john.stultz@linaro.org> In commit c8c43cee29f6 ("driver core: Fix driver_deferred_probe_check_state() logic"), we set the default driver_deferred_probe_timeout value to 30 seconds to allow for drivers that are missing dependencies to have some time so that the dependency may be loaded from userland after initcalls_done is set. However, Yoshihiro Shimoda reported that on his device that expects to have unmet dependencies (due to "optional links" in its devicetree), was failing to mount the NFS root. In digging further, it seemed the problem was that while the device properly probes after waiting 30 seconds for any missing modules to load, the ip_auto_config() had already failed, resulting in NFS to fail. This was due to ip_auto_config() calling wait_for_device_probe() which doesn't wait for the driver_deferred_probe_timeout to fire. This patch tries to fix the issue by creating a waitqueue for the driver_deferred_probe_timeout, and calling wait_event() to make sure driver_deferred_probe_timeout is zero in wait_for_device_probe() to make sure all the probing is finished. The downside to this solution is that kernel functionality that uses wait_for_device_probe(), will block until the driver_deferred_probe_timeout fires, regardless of if there is any missing dependencies. However, the previous patch reverts the default timeout value to zero, so this side-effect will only affect users who specify a driver_deferred_probe_timeout= value as a boot argument, where the additional delay would be beneficial to allow modules to load later during boot. Thanks to Geert for chasing down that ip_auto_config was why NFS was failing in this case! Cc: "David S. Miller" Cc: Alexey Kuznetsov Cc: Hideaki YOSHIFUJI Cc: Jakub Kicinski Cc: Greg Kroah-Hartman Cc: Rafael J. Wysocki Cc: Rob Herring Cc: Geert Uytterhoeven Cc: Yoshihiro Shimoda Cc: Robin Murphy Cc: Andy Shevchenko Cc: Sudeep Holla Cc: Andy Shevchenko Cc: Naresh Kamboju Cc: Basil Eljuse Cc: Ferry Toth Cc: Arnd Bergmann Cc: Anders Roxell Cc: netdev Cc: linux-pm@vger.kernel.org Reported-by: Yoshihiro Shimoda Tested-by: Yoshihiro Shimoda Fixes: c8c43cee29f6 ("driver core: Fix driver_deferred_probe_check_state() logic") Signed-off-by: John Stultz --- drivers/base/dd.c | 5 +++++ 1 file changed, 5 insertions(+) -- 2.17.1 diff --git a/drivers/base/dd.c b/drivers/base/dd.c index 9c88afa5c74a..94037be7f5d7 100644 --- a/drivers/base/dd.c +++ b/drivers/base/dd.c @@ -226,6 +226,7 @@ DEFINE_SHOW_ATTRIBUTE(deferred_devs); int driver_deferred_probe_timeout; EXPORT_SYMBOL_GPL(driver_deferred_probe_timeout); +static DECLARE_WAIT_QUEUE_HEAD(probe_timeout_waitqueue); static int __init deferred_probe_timeout_setup(char *str) { @@ -275,6 +276,7 @@ static void deferred_probe_timeout_work_func(struct work_struct *work) list_for_each_entry_safe(private, p, &deferred_probe_pending_list, deferred_probe) dev_info(private->device, "deferred probe pending"); + wake_up(&probe_timeout_waitqueue); } static DECLARE_DELAYED_WORK(deferred_probe_timeout_work, deferred_probe_timeout_work_func); @@ -649,6 +651,9 @@ int driver_probe_done(void) */ void wait_for_device_probe(void) { + /* wait for probe timeout */ + wait_event(probe_timeout_waitqueue, !driver_deferred_probe_timeout); + /* wait for the deferred probe workqueue to finish */ flush_work(&deferred_probe_work);