cregit-Linux how code gets into the kernel

Release 4.12 include/linux/virtio_ring.h

Directory: include/linux
#ifndef _LINUX_VIRTIO_RING_H

#define _LINUX_VIRTIO_RING_H

#include <asm/barrier.h>
#include <linux/irqreturn.h>
#include <uapi/linux/virtio_ring.h>

/*
 * Barriers in virtio are tricky.  Non-SMP virtio guests can't assume
 * they're not on an SMP host system, so they need to assume real
 * barriers.  Non-SMP virtio hosts could skip the barriers, but does
 * anyone care?
 *
 * For virtio_pci on SMP, we don't need to order with respect to MMIO
 * accesses through relaxed memory I/O windows, so virt_mb() et al are
 * sufficient.
 *
 * For using virtio to talk to real devices (eg. other heterogeneous
 * CPUs) we do need real barriers.  In theory, we could be using both
 * kinds of virtio, so it's a runtime decision, and the branch is
 * actually quite cheap.
 */


static inline void virtio_mb(bool weak_barriers) { if (weak_barriers) virt_mb(); else mb(); }

Contributors

PersonTokensPropCommitsCommitProp
Rusty Russell2095.24%150.00%
Michael S. Tsirkin14.76%150.00%
Total21100.00%2100.00%


static inline void virtio_rmb(bool weak_barriers) { if (weak_barriers) virt_rmb(); else rmb(); }

Contributors

PersonTokensPropCommitsCommitProp
Rusty Russell2095.24%150.00%
Michael S. Tsirkin14.76%150.00%
Total21100.00%2100.00%


static inline void virtio_wmb(bool weak_barriers) { if (weak_barriers) virt_wmb(); else wmb(); }

Contributors

PersonTokensPropCommitsCommitProp
Rusty Russell2095.24%150.00%
Michael S. Tsirkin14.76%150.00%
Total21100.00%2100.00%


static inline void virtio_store_mb(bool weak_barriers, __virtio16 *p, __virtio16 v) { if (weak_barriers) { virt_store_mb(*p, v); } else { WRITE_ONCE(*p, v); mb(); } }

Contributors

PersonTokensPropCommitsCommitProp
Michael S. Tsirkin45100.00%1100.00%
Total45100.00%1100.00%

struct virtio_device; struct virtqueue; /* * Creates a virtqueue and allocates the descriptor ring. If * may_reduce_num is set, then this may allocate a smaller ring than * expected. The caller should query virtqueue_get_ring_size to learn * the actual size of the ring. */ struct virtqueue *vring_create_virtqueue(unsigned int index, unsigned int num, unsigned int vring_align, struct virtio_device *vdev, bool weak_barriers, bool may_reduce_num, bool ctx, bool (*notify)(struct virtqueue *vq), void (*callback)(struct virtqueue *vq), const char *name); /* Creates a virtqueue with a custom layout. */ struct virtqueue *__vring_new_virtqueue(unsigned int index, struct vring vring, struct virtio_device *vdev, bool weak_barriers, bool ctx, bool (*notify)(struct virtqueue *), void (*callback)(struct virtqueue *), const char *name); /* * Creates a virtqueue with a standard layout but a caller-allocated * ring. */ struct virtqueue *vring_new_virtqueue(unsigned int index, unsigned int num, unsigned int vring_align, struct virtio_device *vdev, bool weak_barriers, bool ctx, void *pages, bool (*notify)(struct virtqueue *vq), void (*callback)(struct virtqueue *vq), const char *name); /* * Destroys a virtqueue. If created with vring_create_virtqueue, this * also frees the ring. */ void vring_del_virtqueue(struct virtqueue *vq); /* Filter out transport-specific feature bits. */ void vring_transport_features(struct virtio_device *vdev); irqreturn_t vring_interrupt(int irq, void *_vq); #endif /* _LINUX_VIRTIO_RING_H */

Overall Contributors

PersonTokensPropCommitsCommitProp
Rusty Russell16347.66%746.67%
Andrew Lutomirski11132.46%16.67%
Michael S. Tsirkin6117.84%426.67%
Jason (Hui) Wang41.17%16.67%
David Howells20.58%16.67%
Heinz Graalfs10.29%16.67%
Total342100.00%15100.00%
Directory: include/linux
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