During machine kexec, the function machine_kexec_mask_interrupts() is
responsible for disabling or masking all interrupts. While the irq_disable
hook ensures that an already-disabled IRQ is not disabled again, the
current implementation unconditionally invokes the irq_mask() function for
every interrupt descriptor, even when the interrupt is already masked.

A specific issue was observed in the crash kernel flow after unbinding a
device (prior to kexec) that used a GPIO as an IRQ source. The warning was
triggered by the gpiochip_disable_irq() function, which attempted to clear
the FLAG_IRQ_IS_ENABLED flag when FLAG_USED_AS_IRQ was not set:

```
void gpiochip_disable_irq(struct gpio_chip *gc, unsigned int offset)
{
	struct gpio_desc *desc = gpiochip_get_desc(gc, offset);

	if (!IS_ERR(desc) &&
	    !WARN_ON(!test_bit(FLAG_USED_AS_IRQ, &desc->flags)))
		clear_bit(FLAG_IRQ_IS_ENABLED, &desc->flags);
}
```

This issue surfaced after commit a8173820f441 ("gpio: gpiolib: Allow GPIO
IRQs to lazy disable") introduced lazy disablement for GPIO IRQs. It
replaced disable/enable hooks with mask/unmask hooks. Unlike the disable
hook, the mask hook doesn't handle already-masked IRQs.

When a GPIO-IRQ driver is unbound, the IRQ is released, triggering
__irq_disable() and irq_state_set_masked(). A subsequent call to
machine_kexec_mask_interrupts() re-invokes chip->irq_mask(). This results
in a call chain, including gpiochip_irq_mask() and gpiochip_disable_irq().
Since FLAG_USED_AS_IRQ was cleared earlier, a warning occurs.

This patch addresses the issue by:
 - Replacing the calls to irq_mask() and irq_disable() hooks with a
   simplified call to irq_shutdown().
 - Checking if the interrupt is started (irqd_is_started) before calling
   the shutdown.

As part of this change, the irq_shutdown() declaration was moved from
kernel/irq/internals.h to include/linux/irq.h to make it accessible
outside the kernel/irq/ directory, as the former can only be included
within that directory.

Signed-off-by: Eliav Farber <farbere@amazon.com>
---
V2 -> V3:
 - Check if IRQ is started using irqd_is_started().
 - Use irq_shutdown() instead of irq_disable().

 include/linux/irq.h    | 3 +++
 kernel/irq/internals.h | 1 -
 kernel/kexec_core.c    | 8 ++------
 3 files changed, 5 insertions(+), 7 deletions(-)

diff --git a/include/linux/irq.h b/include/linux/irq.h
index fa711f80957b..48a3df728c47 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -694,6 +694,9 @@ extern int irq_chip_request_resources_parent(struct irq_data *data);
 extern void irq_chip_release_resources_parent(struct irq_data *data);
 #endif
 
+/* Shut down the interrupt */
+extern void irq_shutdown(struct irq_desc *desc);
+
 /* Handling of unhandled and spurious interrupts: */
 extern void note_interrupt(struct irq_desc *desc, irqreturn_t action_ret);
 
diff --git a/kernel/irq/internals.h b/kernel/irq/internals.h
index fe0272cd84a5..1f9287b1ccb7 100644
--- a/kernel/irq/internals.h
+++ b/kernel/irq/internals.h
@@ -88,7 +88,6 @@ extern int irq_activate(struct irq_desc *desc);
 extern int irq_activate_and_startup(struct irq_desc *desc, bool resend);
 extern int irq_startup(struct irq_desc *desc, bool resend, bool force);
 
-extern void irq_shutdown(struct irq_desc *desc);
 extern void irq_shutdown_and_deactivate(struct irq_desc *desc);
 extern void irq_enable(struct irq_desc *desc);
 extern void irq_disable(struct irq_desc *desc);
diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index 6e1e420946e0..928b4387502b 100644
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -1083,7 +1083,7 @@ void machine_kexec_mask_interrupts(void)
 		int check_eoi = 1;
 
 		chip = irq_desc_get_chip(desc);
-		if (!chip)
+		if (!chip || !irqd_is_started(&desc->irq_data))
 			continue;
 
 		if (IS_ENABLED(CONFIG_ARM64)) {
@@ -1097,10 +1097,6 @@ void machine_kexec_mask_interrupts(void)
 		if (check_eoi && chip->irq_eoi && irqd_irq_inprogress(&desc->irq_data))
 			chip->irq_eoi(&desc->irq_data);
 
-		if (chip->irq_mask)
-			chip->irq_mask(&desc->irq_data);
-
-		if (chip->irq_disable && !irqd_irq_disabled(&desc->irq_data))
-			chip->irq_disable(&desc->irq_data);
+		irq_shutdown(desc);
 	}
 }
-- 
2.40.1

Hi Eliav,

kernel test robot noticed the following build errors:

[auto build test ERROR on powerpc/next]
[also build test ERROR on powerpc/fixes tip/irq/core arm64/for-next/core linus/master v6.12 next-20241128]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Eliav-Farber/kexec-Consolidate-machine_kexec_mask_interrupts-implementation/20241129-041259
base:   https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git next
patch link:    https://lore.kernel.org/r/20241128201027.10396-3-farbere%40amazon.com
patch subject: [PATCH v3 2/2] kexec: Prevent redundant IRQ masking by checking state before shutdown
config: x86_64-rhel-9.4 (https://download.01.org/0day-ci/archive/20241129/202411291251.RwA1dKZL-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20241129/202411291251.RwA1dKZL-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202411291251.RwA1dKZL-lkp@intel.com/

All errors (new ones prefixed by >>):

   kernel/kexec_core.c: In function 'machine_kexec_mask_interrupts':
   kernel/kexec_core.c:1085:24: error: implicit declaration of function 'irq_desc_get_chip' [-Werror=implicit-function-declaration]
    1085 |                 chip = irq_desc_get_chip(desc);
         |                        ^~~~~~~~~~~~~~~~~
   kernel/kexec_core.c:1085:22: warning: assignment to 'struct irq_chip *' from 'int' makes pointer from integer without a cast [-Wint-conversion]
    1085 |                 chip = irq_desc_get_chip(desc);
         |                      ^
>> kernel/kexec_core.c:1086:31: error: implicit declaration of function 'irqd_is_started' [-Werror=implicit-function-declaration]
    1086 |                 if (!chip || !irqd_is_started(&desc->irq_data))
         |                               ^~~~~~~~~~~~~~~
   kernel/kexec_core.c:1086:52: error: invalid use of undefined type 'struct irq_desc'
    1086 |                 if (!chip || !irqd_is_started(&desc->irq_data))
         |                                                    ^~
   kernel/kexec_core.c:1097:38: error: invalid use of undefined type 'struct irq_chip'
    1097 |                 if (check_eoi && chip->irq_eoi && irqd_irq_inprogress(&desc->irq_data))
         |                                      ^~
   kernel/kexec_core.c:1097:51: error: implicit declaration of function 'irqd_irq_inprogress' [-Werror=implicit-function-declaration]
    1097 |                 if (check_eoi && chip->irq_eoi && irqd_irq_inprogress(&desc->irq_data))
         |                                                   ^~~~~~~~~~~~~~~~~~~
   kernel/kexec_core.c:1097:76: error: invalid use of undefined type 'struct irq_desc'
    1097 |                 if (check_eoi && chip->irq_eoi && irqd_irq_inprogress(&desc->irq_data))
         |                                                                            ^~
   kernel/kexec_core.c:1098:29: error: invalid use of undefined type 'struct irq_chip'
    1098 |                         chip->irq_eoi(&desc->irq_data);
         |                             ^~
   kernel/kexec_core.c:1098:44: error: invalid use of undefined type 'struct irq_desc'
    1098 |                         chip->irq_eoi(&desc->irq_data);
         |                                            ^~
>> kernel/kexec_core.c:1100:17: error: implicit declaration of function 'irq_shutdown'; did you mean 'timer_shutdown'? [-Werror=implicit-function-declaration]
    1100 |                 irq_shutdown(desc);
         |                 ^~~~~~~~~~~~
         |                 timer_shutdown
   cc1: some warnings being treated as errors


vim +/irqd_is_started +1086 kernel/kexec_core.c

  1075	
  1076	void machine_kexec_mask_interrupts(void)
  1077	{
  1078		unsigned int i;
  1079		struct irq_desc *desc;
  1080	
  1081		for_each_irq_desc(i, desc) {
  1082			struct irq_chip *chip;
  1083			int check_eoi = 1;
  1084	
  1085			chip = irq_desc_get_chip(desc);
> 1086			if (!chip || !irqd_is_started(&desc->irq_data))
  1087				continue;
  1088	
  1089			if (IS_ENABLED(CONFIG_ARM64)) {
  1090				/*
  1091				 * First try to remove the active state. If this fails, try to EOI the
  1092				 * interrupt.
  1093				 */
  1094				check_eoi = irq_set_irqchip_state(i, IRQCHIP_STATE_ACTIVE, false);
  1095			}
  1096	
  1097			if (check_eoi && chip->irq_eoi && irqd_irq_inprogress(&desc->irq_data))
  1098				chip->irq_eoi(&desc->irq_data);
  1099	
> 1100			irq_shutdown(desc);

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki