Patch "genirq: Allow irq_chip registration functions to take a const irq_chip" has been added to the 5.4-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

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

    genirq: Allow irq_chip registration functions to take a const irq_chip

to the 5.4-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:
     genirq-allow-irq_chip-registration-functions-to-take.patch
and it can be found in the queue-5.4 subdirectory.

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



commit efb701bc04af40c136a7815c4ad20c6ffef584b5
Author: Marc Zyngier <maz@xxxxxxxxxx>
Date:   Wed Feb 9 16:25:59 2022 +0000

    genirq: Allow irq_chip registration functions to take a const irq_chip
    
    [ Upstream commit 393e1280f765661cf39785e967676a4e57324126 ]
    
    In order to let a const irqchip be fed to the irqchip layer, adjust
    the various prototypes. An extra cast in irq_set_chip()() is required
    to avoid a warning.
    
    Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
    Acked-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
    Link: https://lore.kernel.org/r/20220209162607.1118325-3-maz@xxxxxxxxxx
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/include/linux/irq.h b/include/linux/irq.h
index 5655da9eb1fb9..0c3f153f60670 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -677,10 +677,11 @@ extern struct irq_chip no_irq_chip;
 extern struct irq_chip dummy_irq_chip;
 
 extern void
-irq_set_chip_and_handler_name(unsigned int irq, struct irq_chip *chip,
+irq_set_chip_and_handler_name(unsigned int irq, const struct irq_chip *chip,
 			      irq_flow_handler_t handle, const char *name);
 
-static inline void irq_set_chip_and_handler(unsigned int irq, struct irq_chip *chip,
+static inline void irq_set_chip_and_handler(unsigned int irq,
+					    const struct irq_chip *chip,
 					    irq_flow_handler_t handle)
 {
 	irq_set_chip_and_handler_name(irq, chip, handle, NULL);
@@ -770,7 +771,7 @@ static inline void irq_set_percpu_devid_flags(unsigned int irq)
 }
 
 /* Set/get chip/data for an IRQ: */
-extern int irq_set_chip(unsigned int irq, struct irq_chip *chip);
+extern int irq_set_chip(unsigned int irq, const struct irq_chip *chip);
 extern int irq_set_handler_data(unsigned int irq, void *data);
 extern int irq_set_chip_data(unsigned int irq, void *data);
 extern int irq_set_irq_type(unsigned int irq, unsigned int type);
diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index 498f76beb8766..5f85eac6af11b 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -38,7 +38,7 @@ struct irqaction chained_action = {
  *	@irq:	irq number
  *	@chip:	pointer to irq chip description structure
  */
-int irq_set_chip(unsigned int irq, struct irq_chip *chip)
+int irq_set_chip(unsigned int irq, const struct irq_chip *chip)
 {
 	unsigned long flags;
 	struct irq_desc *desc = irq_get_desc_lock(irq, &flags, 0);
@@ -46,10 +46,7 @@ int irq_set_chip(unsigned int irq, struct irq_chip *chip)
 	if (!desc)
 		return -EINVAL;
 
-	if (!chip)
-		chip = &no_irq_chip;
-
-	desc->irq_data.chip = chip;
+	desc->irq_data.chip = (struct irq_chip *)(chip ?: &no_irq_chip);
 	irq_put_desc_unlock(desc, flags);
 	/*
 	 * For !CONFIG_SPARSE_IRQ make the irq show up in
@@ -1086,7 +1083,7 @@ irq_set_chained_handler_and_data(unsigned int irq, irq_flow_handler_t handle,
 EXPORT_SYMBOL_GPL(irq_set_chained_handler_and_data);
 
 void
-irq_set_chip_and_handler_name(unsigned int irq, struct irq_chip *chip,
+irq_set_chip_and_handler_name(unsigned int irq, const struct irq_chip *chip,
 			      irq_flow_handler_t handle, const char *name)
 {
 	irq_set_chip(irq, chip);