5.10-stable patches

added patches:
	rtc-cmos-use-spin_lock_irqsave-in-cmos_interrupt.patch

diff --git a/queue-5.10/rtc-cmos-use-spin_lock_irqsave-in-cmos_interrupt.patch b/queue-5.10/rtc-cmos-use-spin_lock_irqsave-in-cmos_interrupt.patch
new file mode 100644 (file)
index 0000000..06e4a09
--- /dev/null
+++ b/queue-5.10/rtc-cmos-use-spin_lock_irqsave-in-cmos_interrupt.patch
@@ -0,0 +1,80 @@
+From 00a39d8652ff9088de07a6fe6e9e1893452fe0dd Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Mateusz=20Jo=C5=84czyk?= <mat.jonczyk@o2.pl>
+Date: Sat, 7 Jun 2025 23:06:08 +0200
+Subject: rtc: cmos: use spin_lock_irqsave in cmos_interrupt
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+From: Mateusz Jończyk <mat.jonczyk@o2.pl>
+
+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>
+---
+ drivers/rtc/rtc-cmos.c |   10 ++++++----
+ 1 file changed, 6 insertions(+), 4 deletions(-)
+
+--- a/drivers/rtc/rtc-cmos.c
++++ b/drivers/rtc/rtc-cmos.c
+@@ -704,8 +704,12 @@ static irqreturn_t cmos_interrupt(int ir
+ {
+       u8              irqstat;
+       u8              rtc_control;
++      unsigned long   flags;
+ 
+-      spin_lock(&rtc_lock);
++      /* We cannot use spin_lock() here, as cmos_interrupt() is also called
++       * in a non-irq context.
++       */
++      spin_lock_irqsave(&rtc_lock, flags);
+ 
+       /* When the HPET interrupt handler calls us, the interrupt
+        * status is passed as arg1 instead of the irq number.  But
+@@ -739,7 +743,7 @@ static irqreturn_t cmos_interrupt(int ir
+                       hpet_mask_rtc_irq_bit(RTC_AIE);
+               CMOS_READ(RTC_INTR_FLAGS);
+       }
+-      spin_unlock(&rtc_lock);
++      spin_unlock_irqrestore(&rtc_lock, flags);
+ 
+       if (is_intr(irqstat)) {
+               rtc_update_irq(p, 1, irqstat);
+@@ -1289,9 +1293,7 @@ static void cmos_check_wkalrm(struct dev
+        * ACK the rtc irq here
+        */
+       if (t_now >= cmos->alarm_expires && cmos_use_acpi_alarm()) {
+-              local_irq_disable();
+               cmos_interrupt(0, (void *)cmos->rtc);
+-              local_irq_enable();
+               return;
+       }
+ 

diff --git a/queue-5.10/series b/queue-5.10/series
index de26ed04d6c3abb74a0c440f6d8ce93ee11bfdf1..3c4d8ed637ece993dc94e582a8f7924fd2f70b25 100644 (file)
--- a/queue-5.10/series
+++ b/queue-5.10/series
@@ -77,3 +77,4 @@ pci-hv-do-not-set-pci_command_memory-to-reduce-vm-boot-time.patch
 s390-add-std-gnu11-to-decompressor-and-purgatory-cflags.patch
 revert-ipv6-save-dontfrag-in-cork.patch
 arm64-restrict-pagetable-teardown-to-avoid-false-warning.patch
+rtc-cmos-use-spin_lock_irqsave-in-cmos_interrupt.patch