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VOP is broken in mainline since commit1ce9e6055f("virtio_ring: introduce packed ring support"); attempting to use the virtqueues leads to various kernel crashes. I'm testing it with my not-yet-merged loopback patches, but even the in-tree MIC hardware cannot work. The problem is not in the referenced commit per se, but is due to the following hack in vop_find_vq() which depends on the layout of private structures in other source files, which that commit happened to change: /* * To reassign the used ring here we are directly accessing * struct vring_virtqueue which is a private data structure * in virtio_ring.c. At the minimum, a BUILD_BUG_ON() in * vring_new_virtqueue() would ensure that * (&vq->vring == (struct vring *) (&vq->vq + 1)); */ vr = (struct vring *)(vq + 1); vr->used = used; Fix vop by using __vring_new_virtqueue() to create the needed vring layout from the start, instead of attempting to patch in the used ring later. __vring_new_virtqueue() was added way back in commit2a2d1382fe("virtio: Add improved queue allocation API") in order to address mic's usecase, according to the commit message. Fixes:1ce9e6055f("virtio_ring: introduce packed ring support") Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.