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Wysocki" , Pavel Machek , Len Brown Cc: Tomasz Figa , Douglas Anderson , Greg Kroah-Hartman , linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org Subject: [PATCH v2] PM / core: Allow configuring the DPM watchdog to warn earlier than panic Date: Thu, 9 Jan 2025 12:59:58 -0800 Message-ID: <20250109125957.v2.1.I4554f931b8da97948f308ecc651b124338ee9603@changeid> X-Mailer: git-send-email 2.47.1.688.g23fc6f90ad-goog Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Allow configuring the DPM watchdog to warn about slow suspend/resume functions without causing a system panic(). This allows you to set the DPM_WATCHDOG_WARNING_TIMEOUT to something like 5 or 10 seconds to get warnings about slow suspend/resume functions that eventually succeed. Signed-off-by: Douglas Anderson Reviewed-by: Tomasz Figa --- Changes in v2: - Print the warning at warn level, not emergency level. - Add help text to DPM_WATCHDOG_WARNING_TIMEOUT. drivers/base/power/main.c | 24 +++++++++++++++++++----- kernel/power/Kconfig | 21 ++++++++++++++++++++- 2 files changed, 39 insertions(+), 6 deletions(-) diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c index 4a67e83300e1..7d60610437a4 100644 --- a/drivers/base/power/main.c +++ b/drivers/base/power/main.c @@ -496,6 +496,7 @@ struct dpm_watchdog { struct device *dev; struct task_struct *tsk; struct timer_list timer; + bool fatal; }; =20 #define DECLARE_DPM_WATCHDOG_ON_STACK(wd) \ @@ -512,11 +513,23 @@ struct dpm_watchdog { static void dpm_watchdog_handler(struct timer_list *t) { struct dpm_watchdog *wd =3D from_timer(wd, t, timer); + struct timer_list *timer =3D &wd->timer; + unsigned int time_left; + + if (wd->fatal) { + dev_emerg(wd->dev, "**** DPM device timeout ****\n"); + show_stack(wd->tsk, NULL, KERN_EMERG); + panic("%s %s: unrecoverable failure\n", + dev_driver_string(wd->dev), dev_name(wd->dev)); + } + + time_left =3D CONFIG_DPM_WATCHDOG_TIMEOUT - CONFIG_DPM_WATCHDOG_WARNING_T= IMEOUT; + dev_warn(wd->dev, "**** DPM device timeout after %u seconds; %u seconds u= ntil panic ****\n", + CONFIG_DPM_WATCHDOG_WARNING_TIMEOUT, time_left); + show_stack(wd->tsk, NULL, KERN_WARNING); =20 - dev_emerg(wd->dev, "**** DPM device timeout ****\n"); - show_stack(wd->tsk, NULL, KERN_EMERG); - panic("%s %s: unrecoverable failure\n", - dev_driver_string(wd->dev), dev_name(wd->dev)); + wd->fatal =3D true; + mod_timer(timer, jiffies + HZ * time_left); } =20 /** @@ -530,10 +543,11 @@ static void dpm_watchdog_set(struct dpm_watchdog *wd,= struct device *dev) =20 wd->dev =3D dev; wd->tsk =3D current; + wd->fatal =3D CONFIG_DPM_WATCHDOG_TIMEOUT =3D=3D CONFIG_DPM_WATCHDOG_WARN= ING_TIMEOUT; =20 timer_setup_on_stack(timer, dpm_watchdog_handler, 0); /* use same timeout value for both suspend and resume */ - timer->expires =3D jiffies + HZ * CONFIG_DPM_WATCHDOG_TIMEOUT; + timer->expires =3D jiffies + HZ * CONFIG_DPM_WATCHDOG_WARNING_TIMEOUT; add_timer(timer); } =20 diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig index afce8130d8b9..ca947ed32e3d 100644 --- a/kernel/power/Kconfig +++ b/kernel/power/Kconfig @@ -257,11 +257,30 @@ config DPM_WATCHDOG boot session. =20 config DPM_WATCHDOG_TIMEOUT - int "Watchdog timeout in seconds" + int "Watchdog timeout to panic in seconds" range 1 120 default 120 depends on DPM_WATCHDOG =20 +config DPM_WATCHDOG_WARNING_TIMEOUT + int "Watchdog timeout to warn in seconds" + range 1 DPM_WATCHDOG_TIMEOUT + default DPM_WATCHDOG_TIMEOUT + depends on DPM_WATCHDOG + help + If the DPM watchdog warning timeout and main timeout are + different then a non-fatal warning (with a stack trace of + the stuck suspend routine) will be printed when the warning + timeout expires. If the suspend routine gets un-stuck + before the main timeout expires then no other action is + taken. If the routine continues to be stuck and the main + timeout expires then an emergency-level message and stack + trace will be printed and the system will panic. + + If the warning timeout is equal to the main timeout (the + default) then the warning will never happen and the system + will jump straight to panic when the main timeout expires. + config PM_TRACE bool help --=20 2.47.1.688.g23fc6f90ad-goog