Patch "gpio: Don't fiddle with irqchips marked as immutable" has been added to the 5.15-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    gpio: Don't fiddle with irqchips marked as immutable

to the 5.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     gpio-don-t-fiddle-with-irqchips-marked-as-immutable.patch
and it can be found in the queue-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 2c04ad8df019c95f15df956c6a7e956d7c5aee2e
Author: Marc Zyngier <maz@xxxxxxxxxx>
Date:   Tue Apr 19 15:18:37 2022 +0100

    gpio: Don't fiddle with irqchips marked as immutable
    
    [ Upstream commit 6c846d026d490b2383d395bc8e7b06336219667b ]
    
    In order to move away from gpiolib messing with the internals of
    unsuspecting irqchips, add a flag by which irqchips advertise
    that they are not to be messed with, and do solemnly swear that
    they correctly call into the gpiolib helpers when required.
    
    Also nudge the users into converting their drivers to the
    new model.
    
    Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
    Reviewed-by: Bartosz Golaszewski <brgl@xxxxxxxx>
    Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
    Link: https://lore.kernel.org/r/20220419141846.598305-2-maz@xxxxxxxxxx
    Stable-dep-of: 08af509efdf8 ("gpio: tqmx86: store IRQ trigger type and unmask status separately")
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 34a061b4becdb..bf77c3f5a4e56 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -1483,6 +1483,11 @@ static void gpiochip_set_irq_hooks(struct gpio_chip *gc)
 {
 	struct irq_chip *irqchip = gc->irq.chip;
 
+	if (irqchip->flags & IRQCHIP_IMMUTABLE)
+		return;
+
+	chip_warn(gc, "not an immutable chip, please consider fixing it!\n");
+
 	if (!irqchip->irq_request_resources &&
 	    !irqchip->irq_release_resources) {
 		irqchip->irq_request_resources = gpiochip_irq_reqres;
@@ -1650,7 +1655,7 @@ static void gpiochip_irqchip_remove(struct gpio_chip *gc)
 		irq_domain_remove(gc->irq.domain);
 	}
 
-	if (irqchip) {
+	if (irqchip && !(irqchip->flags & IRQCHIP_IMMUTABLE)) {
 		if (irqchip->irq_request_resources == gpiochip_irq_reqres) {
 			irqchip->irq_request_resources = NULL;
 			irqchip->irq_release_resources = NULL;
diff --git a/include/linux/irq.h b/include/linux/irq.h
index f9e6449fbbbae..296ef3b7d7afa 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -570,6 +570,7 @@ struct irq_chip {
  * IRQCHIP_ENABLE_WAKEUP_ON_SUSPEND:  Invokes __enable_irq()/__disable_irq() for wake irqs
  *                                    in the suspend path if they are in disabled state
  * IRQCHIP_AFFINITY_PRE_STARTUP:      Default affinity update before startup
+ * IRQCHIP_IMMUTABLE:		      Don't ever change anything in this chip
  */
 enum {
 	IRQCHIP_SET_TYPE_MASKED			= (1 <<  0),
@@ -583,6 +584,7 @@ enum {
 	IRQCHIP_SUPPORTS_NMI			= (1 <<  8),
 	IRQCHIP_ENABLE_WAKEUP_ON_SUSPEND	= (1 <<  9),
 	IRQCHIP_AFFINITY_PRE_STARTUP		= (1 << 10),
+	IRQCHIP_IMMUTABLE			= (1 << 11),
 };
 
 #include <linux/irqdesc.h>
diff --git a/kernel/irq/debugfs.c b/kernel/irq/debugfs.c
index e4cff358b437e..7ff52d94b42c0 100644
--- a/kernel/irq/debugfs.c
+++ b/kernel/irq/debugfs.c
@@ -58,6 +58,7 @@ static const struct irq_bit_descr irqchip_flags[] = {
 	BIT_MASK_DESCR(IRQCHIP_SUPPORTS_LEVEL_MSI),
 	BIT_MASK_DESCR(IRQCHIP_SUPPORTS_NMI),
 	BIT_MASK_DESCR(IRQCHIP_ENABLE_WAKEUP_ON_SUSPEND),
+	BIT_MASK_DESCR(IRQCHIP_IMMUTABLE),
 };
 
 static void