<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/drivers/clocksource, branch v4.4.215</title>
<subtitle>Clone of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git</subtitle>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/'/>
<entry>
<title>clocksource/drivers/sun5i: Fail gracefully when clock rate is unavailable</title>
<updated>2020-01-29T09:21:40+00:00</updated>
<author>
<name>Chen-Yu Tsai</name>
<email>wens@csie.org</email>
</author>
<published>2019-01-10T06:22:07+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=40ae643c0790d6e22a10dd7865bc75090b04ff6a'/>
<id>40ae643c0790d6e22a10dd7865bc75090b04ff6a</id>
<content type='text'>
[ Upstream commit e7e7e0d7beafebd11b0c065cd5fbc1e5759c5aab ]

If the clock tree is not fully populated when the timer-sun5i init code
is called, attempts to get the clock rate for the timer would fail and
return 0.

Make the init code for both clock events and clocksource check the
returned clock rate and fail gracefully if the result is 0, instead of
causing a divide by 0 exception later on.

Fixes: 4a59058f0b09 ("clocksource/drivers/sun5i: Refactor the current code")
Signed-off-by: Chen-Yu Tsai &lt;wens@csie.org&gt;
Acked-by: Maxime Ripard &lt;maxime.ripard@bootlin.com&gt;
Signed-off-by: Daniel Lezcano &lt;daniel.lezcano@linaro.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit e7e7e0d7beafebd11b0c065cd5fbc1e5759c5aab ]

If the clock tree is not fully populated when the timer-sun5i init code
is called, attempts to get the clock rate for the timer would fail and
return 0.

Make the init code for both clock events and clocksource check the
returned clock rate and fail gracefully if the result is 0, instead of
causing a divide by 0 exception later on.

Fixes: 4a59058f0b09 ("clocksource/drivers/sun5i: Refactor the current code")
Signed-off-by: Chen-Yu Tsai &lt;wens@csie.org&gt;
Acked-by: Maxime Ripard &lt;maxime.ripard@bootlin.com&gt;
Signed-off-by: Daniel Lezcano &lt;daniel.lezcano@linaro.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>clocksource/drivers/asm9260: Add a check for of_clk_get</title>
<updated>2020-01-04T12:34:27+00:00</updated>
<author>
<name>Chuhong Yuan</name>
<email>hslester96@gmail.com</email>
</author>
<published>2019-10-16T12:43:30+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=d0eba4f1059ca1b99ad2e8eded69d7b3bb0e8116'/>
<id>d0eba4f1059ca1b99ad2e8eded69d7b3bb0e8116</id>
<content type='text'>
[ Upstream commit 6e001f6a4cc73cd06fc7b8c633bc4906c33dd8ad ]

asm9260_timer_init misses a check for of_clk_get.
Add a check for it and print errors like other clocksource drivers.

Signed-off-by: Chuhong Yuan &lt;hslester96@gmail.com&gt;
Signed-off-by: Daniel Lezcano &lt;daniel.lezcano@linaro.org&gt;
Link: https://lore.kernel.org/r/20191016124330.22211-1-hslester96@gmail.com
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 6e001f6a4cc73cd06fc7b8c633bc4906c33dd8ad ]

asm9260_timer_init misses a check for of_clk_get.
Add a check for it and print errors like other clocksource drivers.

Signed-off-by: Chuhong Yuan &lt;hslester96@gmail.com&gt;
Signed-off-by: Daniel Lezcano &lt;daniel.lezcano@linaro.org&gt;
Link: https://lore.kernel.org/r/20191016124330.22211-1-hslester96@gmail.com
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>clocksource/drivers/exynos_mct: Clear timer interrupt when shutdown</title>
<updated>2019-03-23T07:44:35+00:00</updated>
<author>
<name>Stuart Menefy</name>
<email>stuart.menefy@mathembedded.com</email>
</author>
<published>2019-02-10T22:51:14+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=185ca832f7d74c2bbb4001ea22a5ca0819caa991'/>
<id>185ca832f7d74c2bbb4001ea22a5ca0819caa991</id>
<content type='text'>
commit d2f276c8d3c224d5b493c42b6cf006ae4e64fb1c upstream.

When shutting down the timer, ensure that after we have stopped the
timer any pending interrupts are cleared. This fixes a problem when
suspending, as interrupts are disabled before the timer is stopped,
so the timer interrupt may still be asserted, preventing the system
entering a low power state when the wfi is executed.

Signed-off-by: Stuart Menefy &lt;stuart.menefy@mathembedded.com&gt;
Reviewed-by: Krzysztof Kozlowski &lt;krzk@kernel.org&gt;
Tested-by: Marek Szyprowski &lt;m.szyprowski@samsung.com&gt;
Cc: &lt;stable@vger.kernel.org&gt; # v4.3+
Signed-off-by: Daniel Lezcano &lt;daniel.lezcano@linaro.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit d2f276c8d3c224d5b493c42b6cf006ae4e64fb1c upstream.

When shutting down the timer, ensure that after we have stopped the
timer any pending interrupts are cleared. This fixes a problem when
suspending, as interrupts are disabled before the timer is stopped,
so the timer interrupt may still be asserted, preventing the system
entering a low power state when the wfi is executed.

Signed-off-by: Stuart Menefy &lt;stuart.menefy@mathembedded.com&gt;
Reviewed-by: Krzysztof Kozlowski &lt;krzk@kernel.org&gt;
Tested-by: Marek Szyprowski &lt;m.szyprowski@samsung.com&gt;
Cc: &lt;stable@vger.kernel.org&gt; # v4.3+
Signed-off-by: Daniel Lezcano &lt;daniel.lezcano@linaro.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>clocksource/drivers/exynos_mct: Move one-shot check from tick clear to ISR</title>
<updated>2019-03-23T07:44:35+00:00</updated>
<author>
<name>Stuart Menefy</name>
<email>stuart.menefy@mathembedded.com</email>
</author>
<published>2019-02-10T22:51:13+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=3e08ffef428689e452e169bd23ae7b35affb6f8f'/>
<id>3e08ffef428689e452e169bd23ae7b35affb6f8f</id>
<content type='text'>
commit a5719a40aef956ba704f2aa1c7b977224d60fa96 upstream.

When a timer tick occurs and the clock is in one-shot mode, the timer
needs to be stopped to prevent it triggering subsequent interrupts.
Currently this code is in exynos4_mct_tick_clear(), but as it is
only needed when an ISR occurs move it into exynos4_mct_tick_isr(),
leaving exynos4_mct_tick_clear() just doing what its name suggests it
should.

Signed-off-by: Stuart Menefy &lt;stuart.menefy@mathembedded.com&gt;
Reviewed-by: Krzysztof Kozlowski &lt;krzk@kernel.org&gt;
Tested-by: Marek Szyprowski &lt;m.szyprowski@samsung.com&gt;
Cc: stable@vger.kernel.org # v4.3+
Signed-off-by: Daniel Lezcano &lt;daniel.lezcano@linaro.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit a5719a40aef956ba704f2aa1c7b977224d60fa96 upstream.

When a timer tick occurs and the clock is in one-shot mode, the timer
needs to be stopped to prevent it triggering subsequent interrupts.
Currently this code is in exynos4_mct_tick_clear(), but as it is
only needed when an ISR occurs move it into exynos4_mct_tick_isr(),
leaving exynos4_mct_tick_clear() just doing what its name suggests it
should.

Signed-off-by: Stuart Menefy &lt;stuart.menefy@mathembedded.com&gt;
Reviewed-by: Krzysztof Kozlowski &lt;krzk@kernel.org&gt;
Tested-by: Marek Szyprowski &lt;m.szyprowski@samsung.com&gt;
Cc: stable@vger.kernel.org # v4.3+
Signed-off-by: Daniel Lezcano &lt;daniel.lezcano@linaro.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>clockevents/drivers/i8253: Add support for PIT shutdown quirk</title>
<updated>2018-11-21T08:27:42+00:00</updated>
<author>
<name>Michael Kelley</name>
<email>mikelley@microsoft.com</email>
</author>
<published>2018-11-04T03:48:54+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=989e44d6d2688a9bb162589a719410d6e7898502'/>
<id>989e44d6d2688a9bb162589a719410d6e7898502</id>
<content type='text'>
commit 35b69a420bfb56b7b74cb635ea903db05e357bec upstream.

Add support for platforms where pit_shutdown() doesn't work because of a
quirk in the PIT emulation. On these platforms setting the counter register
to zero causes the PIT to start running again, negating the shutdown.

Provide a global variable that controls whether the counter register is
zero'ed, which platform specific code can override.

Signed-off-by: Michael Kelley &lt;mikelley@microsoft.com&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: "gregkh@linuxfoundation.org" &lt;gregkh@linuxfoundation.org&gt;
Cc: "devel@linuxdriverproject.org" &lt;devel@linuxdriverproject.org&gt;
Cc: "daniel.lezcano@linaro.org" &lt;daniel.lezcano@linaro.org&gt;
Cc: "virtualization@lists.linux-foundation.org" &lt;virtualization@lists.linux-foundation.org&gt;
Cc: "jgross@suse.com" &lt;jgross@suse.com&gt;
Cc: "akataria@vmware.com" &lt;akataria@vmware.com&gt;
Cc: "olaf@aepfle.de" &lt;olaf@aepfle.de&gt;
Cc: "apw@canonical.com" &lt;apw@canonical.com&gt;
Cc: vkuznets &lt;vkuznets@redhat.com&gt;
Cc: "jasowang@redhat.com" &lt;jasowang@redhat.com&gt;
Cc: "marcelo.cerri@canonical.com" &lt;marcelo.cerri@canonical.com&gt;
Cc: KY Srinivasan &lt;kys@microsoft.com&gt;
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/1541303219-11142-2-git-send-email-mikelley@microsoft.com
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 35b69a420bfb56b7b74cb635ea903db05e357bec upstream.

Add support for platforms where pit_shutdown() doesn't work because of a
quirk in the PIT emulation. On these platforms setting the counter register
to zero causes the PIT to start running again, negating the shutdown.

Provide a global variable that controls whether the counter register is
zero'ed, which platform specific code can override.

Signed-off-by: Michael Kelley &lt;mikelley@microsoft.com&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: "gregkh@linuxfoundation.org" &lt;gregkh@linuxfoundation.org&gt;
Cc: "devel@linuxdriverproject.org" &lt;devel@linuxdriverproject.org&gt;
Cc: "daniel.lezcano@linaro.org" &lt;daniel.lezcano@linaro.org&gt;
Cc: "virtualization@lists.linux-foundation.org" &lt;virtualization@lists.linux-foundation.org&gt;
Cc: "jgross@suse.com" &lt;jgross@suse.com&gt;
Cc: "akataria@vmware.com" &lt;akataria@vmware.com&gt;
Cc: "olaf@aepfle.de" &lt;olaf@aepfle.de&gt;
Cc: "apw@canonical.com" &lt;apw@canonical.com&gt;
Cc: vkuznets &lt;vkuznets@redhat.com&gt;
Cc: "jasowang@redhat.com" &lt;jasowang@redhat.com&gt;
Cc: "marcelo.cerri@canonical.com" &lt;marcelo.cerri@canonical.com&gt;
Cc: KY Srinivasan &lt;kys@microsoft.com&gt;
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/1541303219-11142-2-git-send-email-mikelley@microsoft.com
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>clocksource/drivers/ti-32k: Add CLOCK_SOURCE_SUSPEND_NONSTOP flag for non-am43 SoCs</title>
<updated>2018-10-20T07:52:37+00:00</updated>
<author>
<name>Keerthy</name>
<email>j-keerthy@ti.com</email>
</author>
<published>2018-08-08T13:14:59+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=be7e497bf0908851c8744d30c513655b47e386bf'/>
<id>be7e497bf0908851c8744d30c513655b47e386bf</id>
<content type='text'>
[ Upstream commit 3b7d96a0dbb6b630878597a1838fc39f808b761b ]

The 32k clocksource is NONSTOP for non-am43 SoCs. Hence
add the flag for all the other SoCs.

Reported-by: Tony Lindgren &lt;tony@atomide.com&gt;
Signed-off-by: Keerthy &lt;j-keerthy@ti.com&gt;
Acked-by: Tony Lindgren &lt;tony@atomide.com&gt;
Signed-off-by: Daniel Lezcano &lt;daniel.lezcano@linaro.org&gt;
Signed-off-by: Sasha Levin &lt;alexander.levin@microsoft.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 3b7d96a0dbb6b630878597a1838fc39f808b761b ]

The 32k clocksource is NONSTOP for non-am43 SoCs. Hence
add the flag for all the other SoCs.

Reported-by: Tony Lindgren &lt;tony@atomide.com&gt;
Signed-off-by: Keerthy &lt;j-keerthy@ti.com&gt;
Acked-by: Tony Lindgren &lt;tony@atomide.com&gt;
Signed-off-by: Daniel Lezcano &lt;daniel.lezcano@linaro.org&gt;
Signed-off-by: Sasha Levin &lt;alexander.levin@microsoft.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>clocksource/drivers/fsl_ftm_timer: Fix error return checking</title>
<updated>2018-05-30T05:49:01+00:00</updated>
<author>
<name>Colin Ian King</name>
<email>colin.king@canonical.com</email>
</author>
<published>2018-02-26T11:36:14+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=3d95c576aa6e9146360874f954c262a57802e074'/>
<id>3d95c576aa6e9146360874f954c262a57802e074</id>
<content type='text'>
[ Upstream commit f287eb9013ccf199cbfa4eabd80c36fedfc15a73 ]

The error checks on freq for a negative error return always fails because
freq is unsigned and can never be negative. Fix this by making freq a
signed long.

Detected with Coccinelle:
drivers/clocksource/fsl_ftm_timer.c:287:5-9: WARNING: Unsigned expression
compared with zero: freq &lt;= 0
drivers/clocksource/fsl_ftm_timer.c:291:5-9: WARNING: Unsigned expression
compared with zero: freq &lt;= 0

Fixes: 2529c3a33079 ("clocksource: Add Freescale FlexTimer Module (FTM) timer support")
Signed-off-by: Colin Ian King &lt;colin.king@canonical.com&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Daniel Lezcano &lt;daniel.lezcano@linaro.org&gt;
Cc: kernel-janitors@vger.kernel.org
Link: https://lkml.kernel.org/r/20180226113614.3092-1-colin.king@canonical.com
Signed-off-by: Sasha Levin &lt;alexander.levin@microsoft.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit f287eb9013ccf199cbfa4eabd80c36fedfc15a73 ]

The error checks on freq for a negative error return always fails because
freq is unsigned and can never be negative. Fix this by making freq a
signed long.

Detected with Coccinelle:
drivers/clocksource/fsl_ftm_timer.c:287:5-9: WARNING: Unsigned expression
compared with zero: freq &lt;= 0
drivers/clocksource/fsl_ftm_timer.c:291:5-9: WARNING: Unsigned expression
compared with zero: freq &lt;= 0

Fixes: 2529c3a33079 ("clocksource: Add Freescale FlexTimer Module (FTM) timer support")
Signed-off-by: Colin Ian King &lt;colin.king@canonical.com&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Daniel Lezcano &lt;daniel.lezcano@linaro.org&gt;
Cc: kernel-janitors@vger.kernel.org
Link: https://lkml.kernel.org/r/20180226113614.3092-1-colin.king@canonical.com
Signed-off-by: Sasha Levin &lt;alexander.levin@microsoft.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>clockevents/drivers/cs5535: Improve resilience to spurious interrupts</title>
<updated>2017-10-27T08:23:17+00:00</updated>
<author>
<name>David Kozub</name>
<email>zub@linux.fjfi.cvut.cz</email>
</author>
<published>2017-10-19T20:57:02+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=cffdaa65e72f76efc821d551b78ceec1f76196be'/>
<id>cffdaa65e72f76efc821d551b78ceec1f76196be</id>
<content type='text'>
commit eb39a7c0355393c5a8d930f342ad7a6231b552c4 upstream.

The interrupt handler mfgpt_tick() is not robust versus spurious interrupts
which happen before the clock event device is registered and fully
initialized.

The reason is that the safe guard against spurious interrupts solely checks
for the clockevents shutdown state, but lacks a check for detached
state. If the interrupt hits while the device is in detached state it
passes the safe guard and dereferences the event handler call back which is
NULL.

Add the missing state check.

Fixes: 8f9327cbb6e8 ("clockevents/drivers/cs5535: Migrate to new 'set-state' interface")
Suggested-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Signed-off-by: David Kozub &lt;zub@linux.fjfi.cvut.cz&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Daniel Lezcano &lt;daniel.lezcano@linaro.org&gt;
Link: https://lkml.kernel.org/r/20171020093103.3317F6004D@linux.fjfi.cvut.cz
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit eb39a7c0355393c5a8d930f342ad7a6231b552c4 upstream.

The interrupt handler mfgpt_tick() is not robust versus spurious interrupts
which happen before the clock event device is registered and fully
initialized.

The reason is that the safe guard against spurious interrupts solely checks
for the clockevents shutdown state, but lacks a check for detached
state. If the interrupt hits while the device is in detached state it
passes the safe guard and dereferences the event handler call back which is
NULL.

Add the missing state check.

Fixes: 8f9327cbb6e8 ("clockevents/drivers/cs5535: Migrate to new 'set-state' interface")
Suggested-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Signed-off-by: David Kozub &lt;zub@linux.fjfi.cvut.cz&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Daniel Lezcano &lt;daniel.lezcano@linaro.org&gt;
Link: https://lkml.kernel.org/r/20171020093103.3317F6004D@linux.fjfi.cvut.cz
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>clocksource/exynos_mct: Clear interrupt when cpu is shut down</title>
<updated>2017-01-26T07:23:48+00:00</updated>
<author>
<name>Joonyoung Shim</name>
<email>jy0922.shim@samsung.com</email>
</author>
<published>2017-01-17T04:54:36+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=098b62b757a4303f576a6d2bb8f11d0ad93797d1'/>
<id>098b62b757a4303f576a6d2bb8f11d0ad93797d1</id>
<content type='text'>
commit bc7c36eedb0c7004aa06c2afc3c5385adada8fa3 upstream.

When a CPU goes offline a potentially pending timer interrupt is not
cleared. When the CPU comes online again then the pending interrupt is
delivered before the per cpu clockevent device is initialized. As a
consequence the tick interrupt handler dereferences a NULL pointer.

[   51.251378] Unable to handle kernel NULL pointer dereference at virtual address 00000040
[   51.289348] task: ee942d00 task.stack: ee960000
[   51.293861] PC is at tick_periodic+0x38/0xb0
[   51.298102] LR is at tick_handle_periodic+0x1c/0x90

Clear the pending interrupt in the cpu dying path.

Fixes: 56a94f13919c ("clocksource: exynos_mct: Avoid blocking calls in the cpu hotplug notifier")
Reported-by: Seung-Woo Kim &lt;sw0312.kim@samsung.com&gt;
Signed-off-by: Joonyoung Shim &lt;jy0922.shim@samsung.com&gt;
Cc: linux-samsung-soc@vger.kernel.org
Cc: cw00.choi@samsung.com
Cc: daniel.lezcano@linaro.org
Cc: javier@osg.samsung.com
Cc: kgene@kernel.org
Cc: krzk@kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/1484628876-22065-1-git-send-email-jy0922.shim@samsung.com
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

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commit bc7c36eedb0c7004aa06c2afc3c5385adada8fa3 upstream.

When a CPU goes offline a potentially pending timer interrupt is not
cleared. When the CPU comes online again then the pending interrupt is
delivered before the per cpu clockevent device is initialized. As a
consequence the tick interrupt handler dereferences a NULL pointer.

[   51.251378] Unable to handle kernel NULL pointer dereference at virtual address 00000040
[   51.289348] task: ee942d00 task.stack: ee960000
[   51.293861] PC is at tick_periodic+0x38/0xb0
[   51.298102] LR is at tick_handle_periodic+0x1c/0x90

Clear the pending interrupt in the cpu dying path.

Fixes: 56a94f13919c ("clocksource: exynos_mct: Avoid blocking calls in the cpu hotplug notifier")
Reported-by: Seung-Woo Kim &lt;sw0312.kim@samsung.com&gt;
Signed-off-by: Joonyoung Shim &lt;jy0922.shim@samsung.com&gt;
Cc: linux-samsung-soc@vger.kernel.org
Cc: cw00.choi@samsung.com
Cc: daniel.lezcano@linaro.org
Cc: javier@osg.samsung.com
Cc: kgene@kernel.org
Cc: krzk@kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/1484628876-22065-1-git-send-email-jy0922.shim@samsung.com
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

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</entry>
<entry>
<title>clocksource/drivers/sun4i: Clear interrupts after stopping timer in probe function</title>
<updated>2016-09-24T08:07:35+00:00</updated>
<author>
<name>Chen-Yu Tsai</name>
<email>wens@csie.org</email>
</author>
<published>2016-08-25T06:26:59+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=5fa42205ab60c43c021983e6e27301dde103e3c3'/>
<id>5fa42205ab60c43c021983e6e27301dde103e3c3</id>
<content type='text'>
commit b53e7d000d9e6e9fd2c6eb6b82d2783c67fd599e upstream.

The bootloader (U-boot) sometimes uses this timer for various delays.
It uses it as a ongoing counter, and does comparisons on the current
counter value. The timer counter is never stopped.

In some cases when the user interacts with the bootloader, or lets
it idle for some time before loading Linux, the timer may expire,
and an interrupt will be pending. This results in an unexpected
interrupt when the timer interrupt is enabled by the kernel, at
which point the event_handler isn't set yet. This results in a NULL
pointer dereference exception, panic, and no way to reboot.

Clear any pending interrupts after we stop the timer in the probe
function to avoid this.

Signed-off-by: Chen-Yu Tsai &lt;wens@csie.org&gt;
Signed-off-by: Daniel Lezcano &lt;daniel.lezcano@linaro.org&gt;
Acked-by: Maxime Ripard &lt;maxime.ripard@free-electrons.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

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<pre>
commit b53e7d000d9e6e9fd2c6eb6b82d2783c67fd599e upstream.

The bootloader (U-boot) sometimes uses this timer for various delays.
It uses it as a ongoing counter, and does comparisons on the current
counter value. The timer counter is never stopped.

In some cases when the user interacts with the bootloader, or lets
it idle for some time before loading Linux, the timer may expire,
and an interrupt will be pending. This results in an unexpected
interrupt when the timer interrupt is enabled by the kernel, at
which point the event_handler isn't set yet. This results in a NULL
pointer dereference exception, panic, and no way to reboot.

Clear any pending interrupts after we stop the timer in the probe
function to avoid this.

Signed-off-by: Chen-Yu Tsai &lt;wens@csie.org&gt;
Signed-off-by: Daniel Lezcano &lt;daniel.lezcano@linaro.org&gt;
Acked-by: Maxime Ripard &lt;maxime.ripard@free-electrons.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

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