linux-stable.git/drivers/rtc/rtc-cmos.c, branch linux-5.15.y Linux kernel stable tree rtc: cmos: use spin_lock_irqsave in cmos_interrupt 2025-07-10T13:57:42+00:00 Mateusz Jończyk mat.jonczyk@o2.pl 2025-06-07T21:06:08+00:00 1def0038621117d520edea850c4f13c58750881b commit 00a39d8652ff9088de07a6fe6e9e1893452fe0dd upstream. cmos_interrupt() can be called in a non-interrupt context, such as in an ACPI event handler (which runs in an interrupt thread). Therefore, usage of spin_lock(&rtc_lock) is insecure. Use spin_lock_irqsave() / spin_unlock_irqrestore() instead. Before a misguided commit 6950d046eb6e ("rtc: cmos: Replace spin_lock_irqsave with spin_lock in hard IRQ") the cmos_interrupt() function used spin_lock_irqsave(). That commit changed it to spin_lock() and broke locking, which was partially fixed in commit 13be2efc390a ("rtc: cmos: Disable irq around direct invocation of cmos_interrupt()") That second commit did not take account of the ACPI fixed event handler pathway, however. It introduced local_irq_disable() workarounds in cmos_check_wkalrm(), which can cause problems on PREEMPT_RT kernels and are now unnecessary. Add an explicit comment so that this change will not be reverted by mistake. Cc: stable@vger.kernel.org Fixes: 6950d046eb6e ("rtc: cmos: Replace spin_lock_irqsave with spin_lock in hard IRQ") Signed-off-by: Mateusz Jończyk <mat.jonczyk@o2.pl> Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Tested-by: Chris Bainbridge <chris.bainbridge@gmail.com> Reported-by: Chris Bainbridge <chris.bainbridge@gmail.com> Closes: https://lore.kernel.org/all/aDtJ92foPUYmGheF@debian.local/ Link: https://lore.kernel.org/r/20250607210608.14835-1-mat.jonczyk@o2.pl Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 00a39d8652ff9088de07a6fe6e9e1893452fe0dd upstream.

cmos_interrupt() can be called in a non-interrupt context, such as in
an ACPI event handler (which runs in an interrupt thread). Therefore,
usage of spin_lock(&rtc_lock) is insecure. Use spin_lock_irqsave() /
spin_unlock_irqrestore() instead.

Before a misguided
commit 6950d046eb6e ("rtc: cmos: Replace spin_lock_irqsave with spin_lock in hard IRQ")
the cmos_interrupt() function used spin_lock_irqsave(). That commit
changed it to spin_lock() and broke locking, which was partially fixed in
commit 13be2efc390a ("rtc: cmos: Disable irq around direct invocation of cmos_interrupt()")

That second commit did not take account of the ACPI fixed event handler
pathway, however. It introduced local_irq_disable() workarounds in
cmos_check_wkalrm(), which can cause problems on PREEMPT_RT kernels
and are now unnecessary.

Add an explicit comment so that this change will not be reverted by
mistake.

Cc: stable@vger.kernel.org
Fixes: 6950d046eb6e ("rtc: cmos: Replace spin_lock_irqsave with spin_lock in hard IRQ")
Signed-off-by: Mateusz Jończyk <mat.jonczyk@o2.pl>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Tested-by: Chris Bainbridge <chris.bainbridge@gmail.com>
Reported-by: Chris Bainbridge <chris.bainbridge@gmail.com>
Closes: https://lore.kernel.org/all/aDtJ92foPUYmGheF@debian.local/
Link: https://lore.kernel.org/r/20250607210608.14835-1-mat.jonczyk@o2.pl
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
rtc: cmos: Fix return value of nvmem callbacks 2024-08-19T03:45:17+00:00 Joy Chakraborty joychakr@google.com 2024-06-12T08:36:35+00:00 5f60a07fb40fa5ad51d1580e7637922c453bff44 commit 1c184baccf0d5e2ef4cc1562261d0e48508a1c2b upstream. Read/write callbacks registered with nvmem core expect 0 to be returned on success and a negative value to be returned on failure. cmos_nvram_read()/cmos_nvram_write() currently return the number of bytes read or written, fix to return 0 on success and -EIO incase number of bytes requested was not read or written. Fixes: 8b5b7958fd1c ("rtc: cmos: use generic nvmem") Cc: stable@vger.kernel.org Signed-off-by: Joy Chakraborty <joychakr@google.com> Reviewed-by: Dan Carpenter <dan.carpenter@linaro.org> Link: https://lore.kernel.org/r/20240612083635.1253039-1-joychakr@google.com Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 1c184baccf0d5e2ef4cc1562261d0e48508a1c2b upstream.

Read/write callbacks registered with nvmem core expect 0 to be returned
on success and a negative value to be returned on failure.

cmos_nvram_read()/cmos_nvram_write() currently return the number of
bytes read or written, fix to return 0 on success and -EIO incase number
of bytes requested was not read or written.

Fixes: 8b5b7958fd1c ("rtc: cmos: use generic nvmem")
Cc: stable@vger.kernel.org
Signed-off-by: Joy Chakraborty <joychakr@google.com>
Reviewed-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://lore.kernel.org/r/20240612083635.1253039-1-joychakr@google.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
rtc: Adjust failure return code for cmos_set_alarm() 2024-02-23T07:54:26+00:00 Mario Limonciello mario.limonciello@amd.com 2023-11-28T05:36:51+00:00 2d07a63b01ded2c0a58dbc4659c818375ababb38 commit 1311a8f0d4b23f58bbababa13623aa40b8ad4e0c upstream. When mc146818_avoid_UIP() fails to return a valid value, this is because UIP didn't clear in the timeout period. Adjust the return code in this case to -ETIMEDOUT. Tested-by: Mateusz Jończyk <mat.jonczyk@o2.pl> Reviewed-by: Mateusz Jończyk <mat.jonczyk@o2.pl> Acked-by: Mateusz Jończyk <mat.jonczyk@o2.pl> Cc: <stable@vger.kernel.org> Fixes: cdedc45c579f ("rtc: cmos: avoid UIP when reading alarm time") Fixes: cd17420ebea5 ("rtc: cmos: avoid UIP when writing alarm time") Signed-off-by: Mario Limonciello <mario.limonciello@amd.com> Link: https://lore.kernel.org/r/20231128053653.101798-3-mario.limonciello@amd.com Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 1311a8f0d4b23f58bbababa13623aa40b8ad4e0c upstream.

When mc146818_avoid_UIP() fails to return a valid value, this is because
UIP didn't clear in the timeout period. Adjust the return code in this
case to -ETIMEDOUT.

Tested-by: Mateusz Jończyk <mat.jonczyk@o2.pl>
Reviewed-by: Mateusz Jończyk <mat.jonczyk@o2.pl>
Acked-by: Mateusz Jończyk <mat.jonczyk@o2.pl>
Cc:  <stable@vger.kernel.org>
Fixes: cdedc45c579f ("rtc: cmos: avoid UIP when reading alarm time")
Fixes: cd17420ebea5 ("rtc: cmos: avoid UIP when writing alarm time")
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Link: https://lore.kernel.org/r/20231128053653.101798-3-mario.limonciello@amd.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
rtc: cmos: Disable ACPI RTC event on removal 2022-12-31T12:14:34+00:00 Rafael J. Wysocki rafael.j.wysocki@intel.com 2022-11-09T12:15:36+00:00 7a6cc22eab188a0e81ad0a94fff83ed8f4b9d63a [ Upstream commit 83ebb7b3036d151ee39a4a752018665648fc3bd4 ] Make cmos_do_remove() drop the ACPI RTC fixed event handler so as to prevent it from operating on stale data in case the event triggers after driver removal. Fixes: 311ee9c151ad ("rtc: cmos: allow using ACPI for RTC alarm instead of HPET") Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Reviewed-by: Zhang Rui <rui.zhang@intel.com> Tested-by: Zhang Rui <rui.zhang@intel.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://lore.kernel.org/r/2224609.iZASKD2KPV@kreacher Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 83ebb7b3036d151ee39a4a752018665648fc3bd4 ]

Make cmos_do_remove() drop the ACPI RTC fixed event handler so as to
prevent it from operating on stale data in case the event triggers
after driver removal.

Fixes: 311ee9c151ad ("rtc: cmos: allow using ACPI for RTC alarm instead of HPET")
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Zhang Rui <rui.zhang@intel.com>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/2224609.iZASKD2KPV@kreacher
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
rtc: cmos: Rename ACPI-related functions 2022-12-31T12:14:34+00:00 Rafael J. Wysocki rafael.j.wysocki@intel.com 2022-11-09T12:12:00+00:00 689f757f0ab02c352cf655934d488a170cfaab40 [ Upstream commit d13e9ad9f5146f066a5c5a1cc993d09e4fb21ead ] The names of rtc_wake_setup() and cmos_wake_setup() don't indicate that these functions are ACPI-related, which is the case, and the former doesn't really reflect the role of the function. Rename them to acpi_rtc_event_setup() and acpi_cmos_wake_setup(), respectively, to address this shortcoming. No intentional functional impact. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Reviewed-by: Zhang Rui <rui.zhang@intel.com> Tested-by: Zhang Rui <rui.zhang@intel.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://lore.kernel.org/r/3225614.44csPzL39Z@kreacher Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com> Stable-dep-of: 83ebb7b3036d ("rtc: cmos: Disable ACPI RTC event on removal") Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit d13e9ad9f5146f066a5c5a1cc993d09e4fb21ead ]

The names of rtc_wake_setup() and cmos_wake_setup() don't indicate
that these functions are ACPI-related, which is the case, and the
former doesn't really reflect the role of the function.

Rename them to acpi_rtc_event_setup() and acpi_cmos_wake_setup(),
respectively, to address this shortcoming.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Zhang Rui <rui.zhang@intel.com>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/3225614.44csPzL39Z@kreacher
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Stable-dep-of: 83ebb7b3036d ("rtc: cmos: Disable ACPI RTC event on removal")
Signed-off-by: Sasha Levin <sashal@kernel.org>
rtc: cmos: Eliminate forward declarations of some functions 2022-12-31T12:14:34+00:00 Rafael J. Wysocki rafael.j.wysocki@intel.com 2022-11-09T12:09:32+00:00 1c74bbecdabce0da180e2bca5c24bf9ad6ed0d0a [ Upstream commit dca4d3b71c8a09a16951add656711fbd6f5bfbb0 ] Reorder the ACPI-related code before cmos_do_probe() so as to eliminate excessive forward declarations of some functions. While at it, for consistency, add the inline modifier to the definitions of empty stub static funtions and remove it from the corresponding definitions of functions with non-empty bodies. No intentional functional impact. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Reviewed-by: Zhang Rui <rui.zhang@intel.com> Tested-by: Zhang Rui <rui.zhang@intel.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://lore.kernel.org/r/13157911.uLZWGnKmhe@kreacher Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com> Stable-dep-of: 83ebb7b3036d ("rtc: cmos: Disable ACPI RTC event on removal") Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit dca4d3b71c8a09a16951add656711fbd6f5bfbb0 ]

Reorder the ACPI-related code before cmos_do_probe() so as to eliminate
excessive forward declarations of some functions.

While at it, for consistency, add the inline modifier to the
definitions of empty stub static funtions and remove it from the
corresponding definitions of functions with non-empty bodies.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Zhang Rui <rui.zhang@intel.com>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/13157911.uLZWGnKmhe@kreacher
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Stable-dep-of: 83ebb7b3036d ("rtc: cmos: Disable ACPI RTC event on removal")
Signed-off-by: Sasha Levin <sashal@kernel.org>
rtc: cmos: Call rtc_wake_setup() from cmos_do_probe() 2022-12-31T12:14:34+00:00 Rafael J. Wysocki rafael.j.wysocki@intel.com 2022-11-09T12:09:07+00:00 3a439a2cab300c18ed575e09ccd1e5a871300b99 [ Upstream commit 375bbba09692fe4c5218eddee8e312dd733fa846 ] To reduce code duplication, move the invocation of rtc_wake_setup() into cmos_do_probe() and simplify the callers of the latter. No intentional functional impact. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Reviewed-by: Zhang Rui <rui.zhang@intel.com> Tested-by: Zhang Rui <rui.zhang@intel.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://lore.kernel.org/r/2143522.irdbgypaU6@kreacher Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com> Stable-dep-of: 83ebb7b3036d ("rtc: cmos: Disable ACPI RTC event on removal") Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 375bbba09692fe4c5218eddee8e312dd733fa846 ]

To reduce code duplication, move the invocation of rtc_wake_setup()
into cmos_do_probe() and simplify the callers of the latter.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Zhang Rui <rui.zhang@intel.com>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/2143522.irdbgypaU6@kreacher
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Stable-dep-of: 83ebb7b3036d ("rtc: cmos: Disable ACPI RTC event on removal")
Signed-off-by: Sasha Levin <sashal@kernel.org>
rtc: cmos: Call cmos_wake_setup() from cmos_do_probe() 2022-12-31T12:14:34+00:00 Rafael J. Wysocki rafael.j.wysocki@intel.com 2022-11-09T12:07:08+00:00 9febdff75cef8214054fa7aedfbcae2fcf610b16 [ Upstream commit 508ccdfb86b21da37ad091003a4d4567709d5dfb ] Notice that cmos_wake_setup() is the only user of acpi_rtc_info and it can operate on the cmos_rtc variable directly, so it need not set the platform_data pointer before cmos_do_probe() is called. Instead, it can be called by cmos_do_probe() in the case when the platform_data pointer is not set to implement the default behavior (which is to use the FADT information as long as ACPI support is enabled). Modify the code accordingly. While at it, drop a comment that doesn't really match the code it is supposed to be describing. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Reviewed-by: Zhang Rui <rui.zhang@intel.com> Tested-by: Zhang Rui <rui.zhang@intel.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://lore.kernel.org/r/4803444.31r3eYUQgx@kreacher Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com> Stable-dep-of: 83ebb7b3036d ("rtc: cmos: Disable ACPI RTC event on removal") Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 508ccdfb86b21da37ad091003a4d4567709d5dfb ]

Notice that cmos_wake_setup() is the only user of acpi_rtc_info and it
can operate on the cmos_rtc variable directly, so it need not set the
platform_data pointer before cmos_do_probe() is called.  Instead, it
can be called by cmos_do_probe() in the case when the platform_data
pointer is not set to implement the default behavior (which is to use
the FADT information as long as ACPI support is enabled).

Modify the code accordingly.

While at it, drop a comment that doesn't really match the code it is
supposed to be describing.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Zhang Rui <rui.zhang@intel.com>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/4803444.31r3eYUQgx@kreacher
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Stable-dep-of: 83ebb7b3036d ("rtc: cmos: Disable ACPI RTC event on removal")
Signed-off-by: Sasha Levin <sashal@kernel.org>
rtc: cmos: fix build on non-ACPI platforms 2022-12-31T12:14:34+00:00 Alexandre Belloni alexandre.belloni@bootlin.com 2022-10-18T20:35:11+00:00 d9324fb3eed72c984e74f527a96af9200f312b83 [ Upstream commit db4e955ae333567dea02822624106c0b96a2f84f ] Now that rtc_wake_setup is called outside of cmos_wake_setup, it also need to be defined on non-ACPI platforms. Reported-by: kernel test robot <lkp@intel.com> Link: https://lore.kernel.org/r/20221018203512.2532407-1-alexandre.belloni@bootlin.com Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com> Stable-dep-of: 83ebb7b3036d ("rtc: cmos: Disable ACPI RTC event on removal") Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit db4e955ae333567dea02822624106c0b96a2f84f ]

Now that rtc_wake_setup is called outside of cmos_wake_setup, it also need
to be defined on non-ACPI platforms.

Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/r/20221018203512.2532407-1-alexandre.belloni@bootlin.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Stable-dep-of: 83ebb7b3036d ("rtc: cmos: Disable ACPI RTC event on removal")
Signed-off-by: Sasha Levin <sashal@kernel.org>
rtc: cmos: Fix wake alarm breakage 2022-12-31T12:14:34+00:00 Rafael J. Wysocki rafael.j.wysocki@intel.com 2022-10-18T16:09:31+00:00 fe46b9303e32b8e40199c70bd8a8e1acda1a4f8d [ Upstream commit 0782b66ed2fbb035dda76111df0954515e417b24 ] Commit 4919d3eb2ec0 ("rtc: cmos: Fix event handler registration ordering issue") overlooked the fact that cmos_do_probe() depended on the preparations carried out by cmos_wake_setup() and the wake alarm stopped working after the ordering of them had been changed. Address this by partially reverting commit 4919d3eb2ec0 so that cmos_wake_setup() is called before cmos_do_probe() again and moving the rtc_wake_setup() invocation from cmos_wake_setup() directly to the callers of cmos_do_probe() where it will happen after a successful completion of the latter. Fixes: 4919d3eb2ec0 ("rtc: cmos: Fix event handler registration ordering issue") Reported-by: Zhang Rui <rui.zhang@intel.com> Reported-by: Todd Brandt <todd.e.brandt@linux.intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Link: https://lore.kernel.org/r/5887691.lOV4Wx5bFT@kreacher Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com> Stable-dep-of: 83ebb7b3036d ("rtc: cmos: Disable ACPI RTC event on removal") Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 0782b66ed2fbb035dda76111df0954515e417b24 ]

Commit 4919d3eb2ec0 ("rtc: cmos: Fix event handler registration
ordering issue") overlooked the fact that cmos_do_probe() depended
on the preparations carried out by cmos_wake_setup() and the wake
alarm stopped working after the ordering of them had been changed.

Address this by partially reverting commit 4919d3eb2ec0 so that
cmos_wake_setup() is called before cmos_do_probe() again and moving
the rtc_wake_setup() invocation from cmos_wake_setup() directly to the
callers of cmos_do_probe() where it will happen after a successful
completion of the latter.

Fixes: 4919d3eb2ec0 ("rtc: cmos: Fix event handler registration ordering issue")
Reported-by: Zhang Rui <rui.zhang@intel.com>
Reported-by: Todd Brandt <todd.e.brandt@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://lore.kernel.org/r/5887691.lOV4Wx5bFT@kreacher
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Stable-dep-of: 83ebb7b3036d ("rtc: cmos: Disable ACPI RTC event on removal")
Signed-off-by: Sasha Levin <sashal@kernel.org>