Sparse is not happy right now about conditional locking and
complains:

  irqdesc.c:899:17: warning: context imbalance in '__irq_get_desc_lock' - wrong count at exit

Refactor the code and use __acquire() to make it happy.
Annotate the function that it acquires the lock in the
similar way how __irq_put_desc_unlock() is marked.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 kernel/irq/irqdesc.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index 0afc2b0b03be..cecff0cb13eb 100644
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -899,21 +899,22 @@ unsigned int irq_get_next_irq(unsigned int offset)
 struct irq_desc *
 __irq_get_desc_lock(unsigned int irq, unsigned long *flags, bool bus,
 		    unsigned int check)
+	__acquires(&desc->lock)
 {
 	struct irq_desc *desc;
 
 	desc = irq_to_desc(irq);
 	if (!desc)
-		return NULL;
+		goto lock;
 
 	if (check & _IRQ_DESC_CHECK) {
 		if ((check & _IRQ_DESC_PERCPU) &&
 		    !irq_settings_is_per_cpu_devid(desc))
-			return NULL;
+			goto lock;
 
 		if (!(check & _IRQ_DESC_PERCPU) &&
 		    irq_settings_is_per_cpu_devid(desc))
-			return NULL;
+			goto lock;
 	}
 
 	if (bus)
@@ -921,6 +922,10 @@ __irq_get_desc_lock(unsigned int irq, unsigned long *flags, bool bus,
 	raw_spin_lock_irqsave(&desc->lock, *flags);
 
 	return desc;
+
+lock:
+	__acquire(&desc->lock);
+	return NULL;
 }
 
 void __irq_put_desc_unlock(struct irq_desc *desc, unsigned long flags, bool bus)
-- 
2.47.2

On Wed, Apr 16, 2025 at 02:40:34PM +0300, Andy Shevchenko wrote:
> Sparse is not happy right now about conditional locking and
> complains:
> 
>   irqdesc.c:899:17: warning: context imbalance in '__irq_get_desc_lock' - wrong count at exit
> 
> Refactor the code and use __acquire() to make it happy.
> Annotate the function that it acquires the lock in the
> similar way how __irq_put_desc_unlock() is marked.

Oh, scratch this, it basically will diminish the idea for the users.

…

>  __irq_get_desc_lock(unsigned int irq, unsigned long *flags, bool bus,
>  		    unsigned int check)
> +	__acquires(&desc->lock)

This is correct annotation, but it doesn't help alone.
We need __cond_acquires() to be supported by sparse...

...

It can be still fixed by using macros, but this is not probably what we want.
For the reference: d795e38df4b7 ("iio: core: Rework claim and release of direct
mode to work with sparse.")


-- 
With Best Regards,
Andy Shevchenko

On Wed, Apr 16, 2025 at 02:52:18PM +0300, Andy Shevchenko wrote:
> On Wed, Apr 16, 2025 at 02:40:34PM +0300, Andy Shevchenko wrote:
> > Sparse is not happy right now about conditional locking and
> > complains:
> > 
> >   irqdesc.c:899:17: warning: context imbalance in '__irq_get_desc_lock' - wrong count at exit
> > 
> > Refactor the code and use __acquire() to make it happy.
> > Annotate the function that it acquires the lock in the
> > similar way how __irq_put_desc_unlock() is marked.
> 
> Oh, scratch this, it basically will diminish the idea for the users.

That said, the first patch is okay, in case you want it.

-- 
With Best Regards,
Andy Shevchenko