From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrea Arcangeli Subject: [PATCH] thermal: avoid division by zero in power allocator Date: Mon, 28 Sep 2015 23:28:34 +0200 Message-ID: <1443475714-19871-2-git-send-email-aarcange@redhat.com> References: <1443475714-19871-1-git-send-email-aarcange@redhat.com> Return-path: In-Reply-To: <1443475714-19871-1-git-send-email-aarcange@redhat.com> Sender: linux-kernel-owner@vger.kernel.org To: Andrew Morton Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, Javi Merino , Zhang Rui , Eduardo Valentin , Daniel Kurtz List-Id: linux-pm@vger.kernel.org During boot I get a div by zero Oops regression starting in v4.3-rc3. Reviewed-by: Javi Merino Signed-off-by: Andrea Arcangeli --- drivers/thermal/power_allocator.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/drivers/thermal/power_allocator.c b/drivers/thermal/power_allocator.c index 7ff9627..e570ff0 100644 --- a/drivers/thermal/power_allocator.c +++ b/drivers/thermal/power_allocator.c @@ -144,6 +144,16 @@ static void estimate_pid_constants(struct thermal_zone_device *tz, switch_on_temp = 0; temperature_threshold = control_temp - switch_on_temp; + /* + * estimate_pid_constants() tries to find appropriate default + * values for thermal zones that don't provide them. If a + * system integrator has configured a thermal zone with two + * passive trip points at the same temperature, that person + * hasn't put any effort to set up the thermal zone properly + * so just give up. + */ + if (!temperature_threshold) + return; if (!tz->tzp->k_po || force) tz->tzp->k_po = int_to_frac(sustainable_power) /