PCI/MSI: Don't apply affinity if there aren't enough vectors left

Bart reported a problem wіth an out of bounds access in the low-level IRQ
affinity code, which we root caused to the qla2xxx driver assigning all its
MSI-X vectors to the pre and post vectors, and not having any left for the
actually spread IRQs.

Fix this issue by not asking for affinity assignment when there are no
vectors to assign left.

Fixes: 402723ad5c62 ("PCI/MSI: Provide pci_alloc_irq_vectors_affinity()")
Link: https://lkml.kernel.org/r/1485359225.3093.3.camel@sandisk.com
Reported-by: Bart Van Assche <bart.vanassche@sandisk.com>
Tested-by: Bart Van Assche <bart.vanassche@sandisk.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

path: root/sound/usb/caiaq/midi.h

#ifndef CAIAQ_MIDI_H
#define CAIAQ_MIDI_H

int snd_usb_caiaq_midi_init(struct snd_usb_caiaqdev *cdev);
void snd_usb_caiaq_midi_handle_input(struct snd_usb_caiaqdev *cdev,
				     int port, const char *buf, int len);
void snd_usb_caiaq_midi_output_done(struct urb *urb);

#endif /* CAIAQ_MIDI_H */