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/stream.h

#ifndef __USBAUDIO_STREAM_H
#define __USBAUDIO_STREAM_H

int snd_usb_parse_audio_interface(struct snd_usb_audio *chip,
				  int iface_no);

int snd_usb_add_audio_stream(struct snd_usb_audio *chip,
			     int stream,
			     struct audioformat *fp);

#endif /* __USBAUDIO_STREAM_H */