tree 04ba1405061760759ee9e911ff660b03be0cf1b5
parent 234b239bea395316d7f78018c672f4a88b3cdf0d
author David Matlack <dmatlack@google.com> 1411167805 -0700
committer Paolo Bonzini <pbonzini@redhat.com> 1411560475 +0200

kvm: don't take vcpu mutex for obviously invalid vcpu ioctls

vcpu ioctls can hang the calling thread if issued while a vcpu is running.
However, invalid ioctls can happen when userspace tries to probe the kind
of file descriptors (e.g. isatty() calls ioctl(TCGETS)); in that case,
we know the ioctl is going to be rejected as invalid anyway and we can
fail before trying to take the vcpu mutex.

This patch does not change functionality, it just makes invalid ioctls
fail faster.

Cc: stable@vger.kernel.org
Signed-off-by: David Matlack <dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>