Hi Matt, On Sat, Sep 5, 2026 at 9:29 PM Matt Turner <[email protected]> wrote: > > handle_irq() called irq_to_desc() before irq_enter(), so that lookup ran > with the preempt count still saying task context and with RCU not yet > watching. Generic code called from an interrupt handler should see > hardirq context, and irq_to_desc() is more than an array index once > SPARSE_IRQ is in use. > > Move irq_enter() to the top of the function and add the matching > irq_exit() to the invalid interrupt path. > > Assisted-by: Claude:claude-opus-5 > Signed-off-by: Matt Turner <[email protected]> > --- > arch/alpha/kernel/irq.c | 9 ++++++--- > 1 file changed, 6 insertions(+), 3 deletions(-) > > diff --git a/arch/alpha/kernel/irq.c b/arch/alpha/kernel/irq.c > index 4a6a8b1d5a8b..5867a1655045 100644 > --- a/arch/alpha/kernel/irq.c > +++ b/arch/alpha/kernel/irq.c > @@ -107,18 +107,21 @@ handle_irq(int irq) > * handled by some other CPU. (or is disabled) > */ > static unsigned int illegal_count=0; > - struct irq_desc *desc = irq_to_desc(irq); > - > + struct irq_desc *desc; > + > + irq_enter(); > + > + desc = irq_to_desc(irq); > if (!desc || ((unsigned) irq > ACTUAL_NR_IRQS && > illegal_count < MAX_ILLEGAL_IRQS)) { > irq_err_count++; > illegal_count++; > printk(KERN_CRIT "device_interrupt: invalid interrupt %d\n", > irq); > + irq_exit(); > return; > } > > - irq_enter(); > generic_handle_irq_desc(desc); > irq_exit(); > } >
Since this patch is unchanged in v2, and we agreed to handle the hardirq-context consolidation as a follow-up, my tags from reviewing and testing the current change are: Tested-by: Magnus Lindholm <[email protected]> Reviewed-by: Magnus Lindholm <[email protected]> Regards, Magnus
