Fix race in gpio_set_irq_enabled_with_callback #2635
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The order depends on whether you're enabling or disabling
lurch
reviewed
Aug 22, 2025
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| // when enabling, first set callback, then enable the interrupt | ||
| // when disabling, first disable the interrupt, then clear callback | ||
| if (enabled) gpio_set_irq_callback(callback); | ||
| gpio_set_irq_enabled(gpio, events, enabled); | ||
| if (!enabled) gpio_set_irq_callback(callback); | ||
| if (enabled) irq_set_enabled(IO_IRQ_BANK0, true); |
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Is this function likely to get used in performance-critical code? If it is, perhaps it's worth reducing the branches? 🤔 (or is this one of those cases where the compiler is able to do this optimisation automatically?)
Suggested change
| // when enabling, first set callback, then enable the interrupt | |
| // when disabling, first disable the interrupt, then clear callback | |
| if (enabled) gpio_set_irq_callback(callback); | |
| gpio_set_irq_enabled(gpio, events, enabled); | |
| if (!enabled) gpio_set_irq_callback(callback); | |
| if (enabled) irq_set_enabled(IO_IRQ_BANK0, true); | |
| // when enabling, first set callback, then enable the interrupt | |
| // when disabling, first disable the interrupt, then clear callback | |
| if (enabled) { | |
| gpio_set_irq_callback(callback); | |
| gpio_set_irq_enabled(gpio, events, enabled); | |
| irq_set_enabled(IO_IRQ_BANK0, true); | |
| } else { | |
| gpio_set_irq_enabled(gpio, events, enabled); | |
| gpio_set_irq_callback(callback); | |
| } |
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I'll defer to @kilograham on this - I'm happy with either
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it is fine; the compiler will sort it out
kilograham
approved these changes
Sep 10, 2025
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When disabling, if you get an interrupt after
gpio_set_irq_callbackbeforegpio_set_irq_enabledthen you get anunhandled_user_irqFix is to change where you
gpio_set_irq_callbackdepending on whether you're enabling or disabling