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genirq: Ensure flags in lock guard is consistently initialized

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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: 0f70a49f3f ("genirq: Provide conditional lock guards")
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Link: https://lore.kernel.org/all/20250513-irq-guards-fix-flags-init-v1-1-1dca3f5992d6@kernel.org
This commit is contained in:
Nathan Chancellor 2025-05-13 00:16:55 +02:00 committed by Thomas Gleixner
parent c1ab449df8
commit b5fcb68982
1 changed files with 4 additions and 4 deletions
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8
kernel/irq/internals.h
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@ -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;
}