Commit b5fcb689 authored by Nathan Chancellor's avatar Nathan Chancellor Committed by Thomas Gleixner
Browse files

genirq: Ensure flags in lock guard is consistently initialized 



After the conversion to locking guards within the interrupt core code,
several builds with clang show the "Interrupts were enabled early"
WARN() in start_kernel() on boot.

In class_irqdesc_lock_constructor(), _t.flags is initialized via
__irq_get_desc_lock() within the _t initializer list. However, the C11
standard 6.7.9.23 states that the evaluation of the initialization list
expressions are indeterminately sequenced relative to one another,
meaning _t.flags could be initialized by __irq_get_desc_lock() then be
initialized to zero due to flags being absent from the initializer list.

To ensure _t.flags is consistently initialized, move the call to
__irq_get_desc_lock() and the assignment of its result to _t.lock out of
the designated initializer.

Fixes: 0f70a49f ("genirq: Provide conditional lock guards")
Signed-off-by: default avatarNathan Chancellor <nathan@kernel.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarJiri Slaby <jirislaby@kernel.org>
Link: https://lore.kernel.org/all/20250513-irq-guards-fix-flags-init-v1-1-1dca3f5992d6@kernel.org
parent c1ab449d

kernel/irq/internals.h

+4 −4
Original line number Diff line number Diff line
@@ -176,10 +176,10 @@ __DEFINE_UNLOCK_GUARD(irqdesc_lock, struct irq_desc, 
static inline class_irqdesc_lock_t class_irqdesc_lock_constructor(unsigned int irq, bool bus,

								  unsigned int check)

{

	class_irqdesc_lock_t _t = {

		.bus	= bus,

		.lock	= __irq_get_desc_lock(irq, &_t.flags, bus, check),

	};

	class_irqdesc_lock_t _t = { .bus = bus, };



	_t.lock = __irq_get_desc_lock(irq, &_t.flags, bus, check);



	return _t;

}