linux/drivers/virtio/virtio_ring.c
Tejun Heo 5a0e3ad6af include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h
percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files.  percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.

percpu.h -> slab.h dependency is about to be removed.  Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability.  As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.

  http://userweb.kernel.org/~tj/misc/slabh-sweep.py

The script does the followings.

* Scan files for gfp and slab usages and update includes such that
  only the necessary includes are there.  ie. if only gfp is used,
  gfp.h, if slab is used, slab.h.

* When the script inserts a new include, it looks at the include
  blocks and try to put the new include such that its order conforms
  to its surrounding.  It's put in the include block which contains
  core kernel includes, in the same order that the rest are ordered -
  alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
  doesn't seem to be any matching order.

* If the script can't find a place to put a new include (mostly
  because the file doesn't have fitting include block), it prints out
  an error message indicating which .h file needs to be added to the
  file.

The conversion was done in the following steps.

1. The initial automatic conversion of all .c files updated slightly
   over 4000 files, deleting around 700 includes and adding ~480 gfp.h
   and ~3000 slab.h inclusions.  The script emitted errors for ~400
   files.

2. Each error was manually checked.  Some didn't need the inclusion,
   some needed manual addition while adding it to implementation .h or
   embedding .c file was more appropriate for others.  This step added
   inclusions to around 150 files.

3. The script was run again and the output was compared to the edits
   from #2 to make sure no file was left behind.

4. Several build tests were done and a couple of problems were fixed.
   e.g. lib/decompress_*.c used malloc/free() wrappers around slab
   APIs requiring slab.h to be added manually.

5. The script was run on all .h files but without automatically
   editing them as sprinkling gfp.h and slab.h inclusions around .h
   files could easily lead to inclusion dependency hell.  Most gfp.h
   inclusion directives were ignored as stuff from gfp.h was usually
   wildly available and often used in preprocessor macros.  Each
   slab.h inclusion directive was examined and added manually as
   necessary.

6. percpu.h was updated not to include slab.h.

7. Build test were done on the following configurations and failures
   were fixed.  CONFIG_GCOV_KERNEL was turned off for all tests (as my
   distributed build env didn't work with gcov compiles) and a few
   more options had to be turned off depending on archs to make things
   build (like ipr on powerpc/64 which failed due to missing writeq).

   * x86 and x86_64 UP and SMP allmodconfig and a custom test config.
   * powerpc and powerpc64 SMP allmodconfig
   * sparc and sparc64 SMP allmodconfig
   * ia64 SMP allmodconfig
   * s390 SMP allmodconfig
   * alpha SMP allmodconfig
   * um on x86_64 SMP allmodconfig

8. percpu.h modifications were reverted so that it could be applied as
   a separate patch and serve as bisection point.

Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.

Signed-off-by: Tejun Heo <tj@kernel.org>
Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
2010-03-30 22:02:32 +09:00

487 lines
12 KiB
C

/* Virtio ring implementation.
*
* Copyright 2007 Rusty Russell IBM Corporation
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <linux/virtio.h>
#include <linux/virtio_ring.h>
#include <linux/virtio_config.h>
#include <linux/device.h>
#include <linux/slab.h>
/* virtio guest is communicating with a virtual "device" that actually runs on
* a host processor. Memory barriers are used to control SMP effects. */
#ifdef CONFIG_SMP
/* Where possible, use SMP barriers which are more lightweight than mandatory
* barriers, because mandatory barriers control MMIO effects on accesses
* through relaxed memory I/O windows (which virtio does not use). */
#define virtio_mb() smp_mb()
#define virtio_rmb() smp_rmb()
#define virtio_wmb() smp_wmb()
#else
/* We must force memory ordering even if guest is UP since host could be
* running on another CPU, but SMP barriers are defined to barrier() in that
* configuration. So fall back to mandatory barriers instead. */
#define virtio_mb() mb()
#define virtio_rmb() rmb()
#define virtio_wmb() wmb()
#endif
#ifdef DEBUG
/* For development, we want to crash whenever the ring is screwed. */
#define BAD_RING(_vq, fmt, args...) \
do { \
dev_err(&(_vq)->vq.vdev->dev, \
"%s:"fmt, (_vq)->vq.name, ##args); \
BUG(); \
} while (0)
/* Caller is supposed to guarantee no reentry. */
#define START_USE(_vq) \
do { \
if ((_vq)->in_use) \
panic("%s:in_use = %i\n", \
(_vq)->vq.name, (_vq)->in_use); \
(_vq)->in_use = __LINE__; \
} while (0)
#define END_USE(_vq) \
do { BUG_ON(!(_vq)->in_use); (_vq)->in_use = 0; } while(0)
#else
#define BAD_RING(_vq, fmt, args...) \
do { \
dev_err(&_vq->vq.vdev->dev, \
"%s:"fmt, (_vq)->vq.name, ##args); \
(_vq)->broken = true; \
} while (0)
#define START_USE(vq)
#define END_USE(vq)
#endif
struct vring_virtqueue
{
struct virtqueue vq;
/* Actual memory layout for this queue */
struct vring vring;
/* Other side has made a mess, don't try any more. */
bool broken;
/* Host supports indirect buffers */
bool indirect;
/* Number of free buffers */
unsigned int num_free;
/* Head of free buffer list. */
unsigned int free_head;
/* Number we've added since last sync. */
unsigned int num_added;
/* Last used index we've seen. */
u16 last_used_idx;
/* How to notify other side. FIXME: commonalize hcalls! */
void (*notify)(struct virtqueue *vq);
#ifdef DEBUG
/* They're supposed to lock for us. */
unsigned int in_use;
#endif
/* Tokens for callbacks. */
void *data[];
};
#define to_vvq(_vq) container_of(_vq, struct vring_virtqueue, vq)
/* Set up an indirect table of descriptors and add it to the queue. */
static int vring_add_indirect(struct vring_virtqueue *vq,
struct scatterlist sg[],
unsigned int out,
unsigned int in)
{
struct vring_desc *desc;
unsigned head;
int i;
desc = kmalloc((out + in) * sizeof(struct vring_desc), GFP_ATOMIC);
if (!desc)
return vq->vring.num;
/* Transfer entries from the sg list into the indirect page */
for (i = 0; i < out; i++) {
desc[i].flags = VRING_DESC_F_NEXT;
desc[i].addr = sg_phys(sg);
desc[i].len = sg->length;
desc[i].next = i+1;
sg++;
}
for (; i < (out + in); i++) {
desc[i].flags = VRING_DESC_F_NEXT|VRING_DESC_F_WRITE;
desc[i].addr = sg_phys(sg);
desc[i].len = sg->length;
desc[i].next = i+1;
sg++;
}
/* Last one doesn't continue. */
desc[i-1].flags &= ~VRING_DESC_F_NEXT;
desc[i-1].next = 0;
/* We're about to use a buffer */
vq->num_free--;
/* Use a single buffer which doesn't continue */
head = vq->free_head;
vq->vring.desc[head].flags = VRING_DESC_F_INDIRECT;
vq->vring.desc[head].addr = virt_to_phys(desc);
vq->vring.desc[head].len = i * sizeof(struct vring_desc);
/* Update free pointer */
vq->free_head = vq->vring.desc[head].next;
return head;
}
static int vring_add_buf(struct virtqueue *_vq,
struct scatterlist sg[],
unsigned int out,
unsigned int in,
void *data)
{
struct vring_virtqueue *vq = to_vvq(_vq);
unsigned int i, avail, head, uninitialized_var(prev);
START_USE(vq);
BUG_ON(data == NULL);
/* If the host supports indirect descriptor tables, and we have multiple
* buffers, then go indirect. FIXME: tune this threshold */
if (vq->indirect && (out + in) > 1 && vq->num_free) {
head = vring_add_indirect(vq, sg, out, in);
if (head != vq->vring.num)
goto add_head;
}
BUG_ON(out + in > vq->vring.num);
BUG_ON(out + in == 0);
if (vq->num_free < out + in) {
pr_debug("Can't add buf len %i - avail = %i\n",
out + in, vq->num_free);
/* FIXME: for historical reasons, we force a notify here if
* there are outgoing parts to the buffer. Presumably the
* host should service the ring ASAP. */
if (out)
vq->notify(&vq->vq);
END_USE(vq);
return -ENOSPC;
}
/* We're about to use some buffers from the free list. */
vq->num_free -= out + in;
head = vq->free_head;
for (i = vq->free_head; out; i = vq->vring.desc[i].next, out--) {
vq->vring.desc[i].flags = VRING_DESC_F_NEXT;
vq->vring.desc[i].addr = sg_phys(sg);
vq->vring.desc[i].len = sg->length;
prev = i;
sg++;
}
for (; in; i = vq->vring.desc[i].next, in--) {
vq->vring.desc[i].flags = VRING_DESC_F_NEXT|VRING_DESC_F_WRITE;
vq->vring.desc[i].addr = sg_phys(sg);
vq->vring.desc[i].len = sg->length;
prev = i;
sg++;
}
/* Last one doesn't continue. */
vq->vring.desc[prev].flags &= ~VRING_DESC_F_NEXT;
/* Update free pointer */
vq->free_head = i;
add_head:
/* Set token. */
vq->data[head] = data;
/* Put entry in available array (but don't update avail->idx until they
* do sync). FIXME: avoid modulus here? */
avail = (vq->vring.avail->idx + vq->num_added++) % vq->vring.num;
vq->vring.avail->ring[avail] = head;
pr_debug("Added buffer head %i to %p\n", head, vq);
END_USE(vq);
/* If we're indirect, we can fit many (assuming not OOM). */
if (vq->indirect)
return vq->num_free ? vq->vring.num : 0;
return vq->num_free;
}
static void vring_kick(struct virtqueue *_vq)
{
struct vring_virtqueue *vq = to_vvq(_vq);
START_USE(vq);
/* Descriptors and available array need to be set before we expose the
* new available array entries. */
virtio_wmb();
vq->vring.avail->idx += vq->num_added;
vq->num_added = 0;
/* Need to update avail index before checking if we should notify */
virtio_mb();
if (!(vq->vring.used->flags & VRING_USED_F_NO_NOTIFY))
/* Prod other side to tell it about changes. */
vq->notify(&vq->vq);
END_USE(vq);
}
static void detach_buf(struct vring_virtqueue *vq, unsigned int head)
{
unsigned int i;
/* Clear data ptr. */
vq->data[head] = NULL;
/* Put back on free list: find end */
i = head;
/* Free the indirect table */
if (vq->vring.desc[i].flags & VRING_DESC_F_INDIRECT)
kfree(phys_to_virt(vq->vring.desc[i].addr));
while (vq->vring.desc[i].flags & VRING_DESC_F_NEXT) {
i = vq->vring.desc[i].next;
vq->num_free++;
}
vq->vring.desc[i].next = vq->free_head;
vq->free_head = head;
/* Plus final descriptor */
vq->num_free++;
}
static inline bool more_used(const struct vring_virtqueue *vq)
{
return vq->last_used_idx != vq->vring.used->idx;
}
static void *vring_get_buf(struct virtqueue *_vq, unsigned int *len)
{
struct vring_virtqueue *vq = to_vvq(_vq);
void *ret;
unsigned int i;
START_USE(vq);
if (unlikely(vq->broken)) {
END_USE(vq);
return NULL;
}
if (!more_used(vq)) {
pr_debug("No more buffers in queue\n");
END_USE(vq);
return NULL;
}
/* Only get used array entries after they have been exposed by host. */
virtio_rmb();
i = vq->vring.used->ring[vq->last_used_idx%vq->vring.num].id;
*len = vq->vring.used->ring[vq->last_used_idx%vq->vring.num].len;
if (unlikely(i >= vq->vring.num)) {
BAD_RING(vq, "id %u out of range\n", i);
return NULL;
}
if (unlikely(!vq->data[i])) {
BAD_RING(vq, "id %u is not a head!\n", i);
return NULL;
}
/* detach_buf clears data, so grab it now. */
ret = vq->data[i];
detach_buf(vq, i);
vq->last_used_idx++;
END_USE(vq);
return ret;
}
static void vring_disable_cb(struct virtqueue *_vq)
{
struct vring_virtqueue *vq = to_vvq(_vq);
vq->vring.avail->flags |= VRING_AVAIL_F_NO_INTERRUPT;
}
static bool vring_enable_cb(struct virtqueue *_vq)
{
struct vring_virtqueue *vq = to_vvq(_vq);
START_USE(vq);
/* We optimistically turn back on interrupts, then check if there was
* more to do. */
vq->vring.avail->flags &= ~VRING_AVAIL_F_NO_INTERRUPT;
virtio_mb();
if (unlikely(more_used(vq))) {
END_USE(vq);
return false;
}
END_USE(vq);
return true;
}
static void *vring_detach_unused_buf(struct virtqueue *_vq)
{
struct vring_virtqueue *vq = to_vvq(_vq);
unsigned int i;
void *buf;
START_USE(vq);
for (i = 0; i < vq->vring.num; i++) {
if (!vq->data[i])
continue;
/* detach_buf clears data, so grab it now. */
buf = vq->data[i];
detach_buf(vq, i);
END_USE(vq);
return buf;
}
/* That should have freed everything. */
BUG_ON(vq->num_free != vq->vring.num);
END_USE(vq);
return NULL;
}
irqreturn_t vring_interrupt(int irq, void *_vq)
{
struct vring_virtqueue *vq = to_vvq(_vq);
if (!more_used(vq)) {
pr_debug("virtqueue interrupt with no work for %p\n", vq);
return IRQ_NONE;
}
if (unlikely(vq->broken))
return IRQ_HANDLED;
pr_debug("virtqueue callback for %p (%p)\n", vq, vq->vq.callback);
if (vq->vq.callback)
vq->vq.callback(&vq->vq);
return IRQ_HANDLED;
}
EXPORT_SYMBOL_GPL(vring_interrupt);
static struct virtqueue_ops vring_vq_ops = {
.add_buf = vring_add_buf,
.get_buf = vring_get_buf,
.kick = vring_kick,
.disable_cb = vring_disable_cb,
.enable_cb = vring_enable_cb,
.detach_unused_buf = vring_detach_unused_buf,
};
struct virtqueue *vring_new_virtqueue(unsigned int num,
unsigned int vring_align,
struct virtio_device *vdev,
void *pages,
void (*notify)(struct virtqueue *),
void (*callback)(struct virtqueue *),
const char *name)
{
struct vring_virtqueue *vq;
unsigned int i;
/* We assume num is a power of 2. */
if (num & (num - 1)) {
dev_warn(&vdev->dev, "Bad virtqueue length %u\n", num);
return NULL;
}
vq = kmalloc(sizeof(*vq) + sizeof(void *)*num, GFP_KERNEL);
if (!vq)
return NULL;
vring_init(&vq->vring, num, pages, vring_align);
vq->vq.callback = callback;
vq->vq.vdev = vdev;
vq->vq.vq_ops = &vring_vq_ops;
vq->vq.name = name;
vq->notify = notify;
vq->broken = false;
vq->last_used_idx = 0;
vq->num_added = 0;
list_add_tail(&vq->vq.list, &vdev->vqs);
#ifdef DEBUG
vq->in_use = false;
#endif
vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC);
/* No callback? Tell other side not to bother us. */
if (!callback)
vq->vring.avail->flags |= VRING_AVAIL_F_NO_INTERRUPT;
/* Put everything in free lists. */
vq->num_free = num;
vq->free_head = 0;
for (i = 0; i < num-1; i++) {
vq->vring.desc[i].next = i+1;
vq->data[i] = NULL;
}
vq->data[i] = NULL;
return &vq->vq;
}
EXPORT_SYMBOL_GPL(vring_new_virtqueue);
void vring_del_virtqueue(struct virtqueue *vq)
{
list_del(&vq->list);
kfree(to_vvq(vq));
}
EXPORT_SYMBOL_GPL(vring_del_virtqueue);
/* Manipulates transport-specific feature bits. */
void vring_transport_features(struct virtio_device *vdev)
{
unsigned int i;
for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++) {
switch (i) {
case VIRTIO_RING_F_INDIRECT_DESC:
break;
default:
/* We don't understand this bit. */
clear_bit(i, vdev->features);
}
}
}
EXPORT_SYMBOL_GPL(vring_transport_features);
MODULE_LICENSE("GPL");