d0cac39e4e
Based upon a report by Meelis Roos. Sparc64 SBUS and PCI controllers use a combination of IMAP and ICLR registers to manage device interrupts. The IMAP register contains the "valid" enable bit as well as CPU targetting information. Whereas the ICLR register is written with zero at the end of handling an interrupt to reset the state machine for that interrupt to IDLE so it can be sent again. For PCI slot and SBUS slot devices we can have multiple interrupts sharing the same IMAP register. There are individual ICLR registers but only one IMAP register for managing those. We represent each shared case with individual virtual IRQs so the generic IRQ layer thinks there is only one user of the IRQ instance. In such shared IMAP cases this is wrong, so if there are multiple active users then a free_irq() call will prematurely turn off the interrupt by clearing the Valid bit in the IMAP register even though there are other active users. Fix this by simply doing nothing in sun4u_disable_irq() and checking IRQF_DISABLED during IRQ dispatch. This situation doesn't exist in the hypervisor sun4v cases, so I left those alone. Tested-by: Meelis Roos <mroos@linux.ee> Signed-off-by: David S. Miller <davem@davemloft.net> |
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