linux/net/9p/trans_xen.c
Dominique Martinet 39763480dd 9p/net: xen: fix false positive printf format overflow warning
Use the constant to make the compiler happy about this warning:
net/9p/trans_xen.c: In function ‘xen_9pfs_front_changed’:
net/9p/trans_xen.c:444:39: warning: ‘%d’ directive writing between 1 and 11 bytes into a region of size 8 [-Wformat-overflow=]
  444 |                 sprintf(str, "ring-ref%d", i);
      |                                       ^~
In function ‘xen_9pfs_front_init’,
    inlined from ‘xen_9pfs_front_changed’ at net/9p/trans_xen.c:516:8,
    inlined from ‘xen_9pfs_front_changed’ at net/9p/trans_xen.c:504:13:
net/9p/trans_xen.c:444:30: note: directive argument in the range [-2147483644, 2147483646]
  444 |                 sprintf(str, "ring-ref%d", i);
      |                              ^~~~~~~~~~~~
net/9p/trans_xen.c:444:17: note: ‘sprintf’ output between 10 and 20 bytes into a destination of size 16
  444 |                 sprintf(str, "ring-ref%d", i);
      |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
net/9p/trans_xen.c: In function ‘xen_9pfs_front_changed’:
net/9p/trans_xen.c:450:45: warning: ‘%d’ directive writing between 1 and 11 bytes into a region of size 2 [-Wformat-overflow=]
  450 |                 sprintf(str, "event-channel-%d", i);
      |                                             ^~
In function ‘xen_9pfs_front_init’,
    inlined from ‘xen_9pfs_front_changed’ at net/9p/trans_xen.c:516:8,
    inlined from ‘xen_9pfs_front_changed’ at net/9p/trans_xen.c:504:13:
net/9p/trans_xen.c:450:30: note: directive argument in the range [-2147483644, 2147483646]
  450 |                 sprintf(str, "event-channel-%d", i);
      |                              ^~~~~~~~~~~~~~~~~~
net/9p/trans_xen.c:450:17: note: ‘sprintf’ output between 16 and 26 bytes into a destination of size 16
  450 |                 sprintf(str, "event-channel-%d", i);
      |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

There is no change in logic: there only are a constant number of rings,
and there also already is a BUILD_BUG_ON that checks if that constant
goes over 9 as anything bigger would no longer fit the event-channel-%d
destination size.

In theory having that size as part of the struct means it could be
modified by another thread and makes the compiler lose track of possible
values for 'i' here, using the constant directly here makes it work.

Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
Message-ID: <20231025103445.1248103-3-asmadeus@codewreck.org>
Reviewed-by: Christian Schoenebeck <linux_oss@crudebyte.com>
2023-10-27 12:44:08 +09:00

571 lines
13 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* linux/fs/9p/trans_xen
*
* Xen transport layer.
*
* Copyright (C) 2017 by Stefano Stabellini <stefano@aporeto.com>
*/
#include <xen/events.h>
#include <xen/grant_table.h>
#include <xen/xen.h>
#include <xen/xenbus.h>
#include <xen/interface/io/9pfs.h>
#include <linux/module.h>
#include <linux/spinlock.h>
#include <net/9p/9p.h>
#include <net/9p/client.h>
#include <net/9p/transport.h>
#define XEN_9PFS_NUM_RINGS 2
#define XEN_9PFS_RING_ORDER 9
#define XEN_9PFS_RING_SIZE(ring) XEN_FLEX_RING_SIZE(ring->intf->ring_order)
struct xen_9pfs_header {
uint32_t size;
uint8_t id;
uint16_t tag;
/* uint8_t sdata[]; */
} __attribute__((packed));
/* One per ring, more than one per 9pfs share */
struct xen_9pfs_dataring {
struct xen_9pfs_front_priv *priv;
struct xen_9pfs_data_intf *intf;
grant_ref_t ref;
int evtchn;
int irq;
/* protect a ring from concurrent accesses */
spinlock_t lock;
struct xen_9pfs_data data;
wait_queue_head_t wq;
struct work_struct work;
};
/* One per 9pfs share */
struct xen_9pfs_front_priv {
struct list_head list;
struct xenbus_device *dev;
char *tag;
struct p9_client *client;
struct xen_9pfs_dataring *rings;
};
static LIST_HEAD(xen_9pfs_devs);
static DEFINE_RWLOCK(xen_9pfs_lock);
/* We don't currently allow canceling of requests */
static int p9_xen_cancel(struct p9_client *client, struct p9_req_t *req)
{
return 1;
}
static int p9_xen_create(struct p9_client *client, const char *addr, char *args)
{
struct xen_9pfs_front_priv *priv;
if (addr == NULL)
return -EINVAL;
read_lock(&xen_9pfs_lock);
list_for_each_entry(priv, &xen_9pfs_devs, list) {
if (!strcmp(priv->tag, addr)) {
priv->client = client;
read_unlock(&xen_9pfs_lock);
return 0;
}
}
read_unlock(&xen_9pfs_lock);
return -EINVAL;
}
static void p9_xen_close(struct p9_client *client)
{
struct xen_9pfs_front_priv *priv;
read_lock(&xen_9pfs_lock);
list_for_each_entry(priv, &xen_9pfs_devs, list) {
if (priv->client == client) {
priv->client = NULL;
read_unlock(&xen_9pfs_lock);
return;
}
}
read_unlock(&xen_9pfs_lock);
}
static bool p9_xen_write_todo(struct xen_9pfs_dataring *ring, RING_IDX size)
{
RING_IDX cons, prod;
cons = ring->intf->out_cons;
prod = ring->intf->out_prod;
virt_mb();
return XEN_9PFS_RING_SIZE(ring) -
xen_9pfs_queued(prod, cons, XEN_9PFS_RING_SIZE(ring)) >= size;
}
static int p9_xen_request(struct p9_client *client, struct p9_req_t *p9_req)
{
struct xen_9pfs_front_priv *priv;
RING_IDX cons, prod, masked_cons, masked_prod;
unsigned long flags;
u32 size = p9_req->tc.size;
struct xen_9pfs_dataring *ring;
int num;
read_lock(&xen_9pfs_lock);
list_for_each_entry(priv, &xen_9pfs_devs, list) {
if (priv->client == client)
break;
}
read_unlock(&xen_9pfs_lock);
if (list_entry_is_head(priv, &xen_9pfs_devs, list))
return -EINVAL;
num = p9_req->tc.tag % XEN_9PFS_NUM_RINGS;
ring = &priv->rings[num];
again:
while (wait_event_killable(ring->wq,
p9_xen_write_todo(ring, size)) != 0)
;
spin_lock_irqsave(&ring->lock, flags);
cons = ring->intf->out_cons;
prod = ring->intf->out_prod;
virt_mb();
if (XEN_9PFS_RING_SIZE(ring) -
xen_9pfs_queued(prod, cons, XEN_9PFS_RING_SIZE(ring)) < size) {
spin_unlock_irqrestore(&ring->lock, flags);
goto again;
}
masked_prod = xen_9pfs_mask(prod, XEN_9PFS_RING_SIZE(ring));
masked_cons = xen_9pfs_mask(cons, XEN_9PFS_RING_SIZE(ring));
xen_9pfs_write_packet(ring->data.out, p9_req->tc.sdata, size,
&masked_prod, masked_cons,
XEN_9PFS_RING_SIZE(ring));
WRITE_ONCE(p9_req->status, REQ_STATUS_SENT);
virt_wmb(); /* write ring before updating pointer */
prod += size;
ring->intf->out_prod = prod;
spin_unlock_irqrestore(&ring->lock, flags);
notify_remote_via_irq(ring->irq);
p9_req_put(client, p9_req);
return 0;
}
static void p9_xen_response(struct work_struct *work)
{
struct xen_9pfs_front_priv *priv;
struct xen_9pfs_dataring *ring;
RING_IDX cons, prod, masked_cons, masked_prod;
struct xen_9pfs_header h;
struct p9_req_t *req;
int status;
ring = container_of(work, struct xen_9pfs_dataring, work);
priv = ring->priv;
while (1) {
cons = ring->intf->in_cons;
prod = ring->intf->in_prod;
virt_rmb();
if (xen_9pfs_queued(prod, cons, XEN_9PFS_RING_SIZE(ring)) <
sizeof(h)) {
notify_remote_via_irq(ring->irq);
return;
}
masked_prod = xen_9pfs_mask(prod, XEN_9PFS_RING_SIZE(ring));
masked_cons = xen_9pfs_mask(cons, XEN_9PFS_RING_SIZE(ring));
/* First, read just the header */
xen_9pfs_read_packet(&h, ring->data.in, sizeof(h),
masked_prod, &masked_cons,
XEN_9PFS_RING_SIZE(ring));
req = p9_tag_lookup(priv->client, h.tag);
if (!req || req->status != REQ_STATUS_SENT) {
dev_warn(&priv->dev->dev, "Wrong req tag=%x\n", h.tag);
cons += h.size;
virt_mb();
ring->intf->in_cons = cons;
continue;
}
if (h.size > req->rc.capacity) {
dev_warn(&priv->dev->dev,
"requested packet size too big: %d for tag %d with capacity %zd\n",
h.size, h.tag, req->rc.capacity);
WRITE_ONCE(req->status, REQ_STATUS_ERROR);
goto recv_error;
}
req->rc.size = h.size;
req->rc.id = h.id;
req->rc.tag = h.tag;
req->rc.offset = 0;
masked_cons = xen_9pfs_mask(cons, XEN_9PFS_RING_SIZE(ring));
/* Then, read the whole packet (including the header) */
xen_9pfs_read_packet(req->rc.sdata, ring->data.in, h.size,
masked_prod, &masked_cons,
XEN_9PFS_RING_SIZE(ring));
recv_error:
virt_mb();
cons += h.size;
ring->intf->in_cons = cons;
status = (req->status != REQ_STATUS_ERROR) ?
REQ_STATUS_RCVD : REQ_STATUS_ERROR;
p9_client_cb(priv->client, req, status);
}
}
static irqreturn_t xen_9pfs_front_event_handler(int irq, void *r)
{
struct xen_9pfs_dataring *ring = r;
if (!ring || !ring->priv->client) {
/* ignore spurious interrupt */
return IRQ_HANDLED;
}
wake_up_interruptible(&ring->wq);
schedule_work(&ring->work);
return IRQ_HANDLED;
}
static struct p9_trans_module p9_xen_trans = {
.name = "xen",
.maxsize = 1 << (XEN_9PFS_RING_ORDER + XEN_PAGE_SHIFT - 2),
.pooled_rbuffers = false,
.def = 1,
.create = p9_xen_create,
.close = p9_xen_close,
.request = p9_xen_request,
.cancel = p9_xen_cancel,
.owner = THIS_MODULE,
};
static const struct xenbus_device_id xen_9pfs_front_ids[] = {
{ "9pfs" },
{ "" }
};
static void xen_9pfs_front_free(struct xen_9pfs_front_priv *priv)
{
int i, j;
write_lock(&xen_9pfs_lock);
list_del(&priv->list);
write_unlock(&xen_9pfs_lock);
for (i = 0; i < XEN_9PFS_NUM_RINGS; i++) {
struct xen_9pfs_dataring *ring = &priv->rings[i];
cancel_work_sync(&ring->work);
if (!priv->rings[i].intf)
break;
if (priv->rings[i].irq > 0)
unbind_from_irqhandler(priv->rings[i].irq, priv->dev);
if (priv->rings[i].data.in) {
for (j = 0;
j < (1 << priv->rings[i].intf->ring_order);
j++) {
grant_ref_t ref;
ref = priv->rings[i].intf->ref[j];
gnttab_end_foreign_access(ref, NULL);
}
free_pages_exact(priv->rings[i].data.in,
1UL << (priv->rings[i].intf->ring_order +
XEN_PAGE_SHIFT));
}
gnttab_end_foreign_access(priv->rings[i].ref, NULL);
free_page((unsigned long)priv->rings[i].intf);
}
kfree(priv->rings);
kfree(priv->tag);
kfree(priv);
}
static void xen_9pfs_front_remove(struct xenbus_device *dev)
{
struct xen_9pfs_front_priv *priv = dev_get_drvdata(&dev->dev);
dev_set_drvdata(&dev->dev, NULL);
xen_9pfs_front_free(priv);
}
static int xen_9pfs_front_alloc_dataring(struct xenbus_device *dev,
struct xen_9pfs_dataring *ring,
unsigned int order)
{
int i = 0;
int ret = -ENOMEM;
void *bytes = NULL;
init_waitqueue_head(&ring->wq);
spin_lock_init(&ring->lock);
INIT_WORK(&ring->work, p9_xen_response);
ring->intf = (struct xen_9pfs_data_intf *)get_zeroed_page(GFP_KERNEL);
if (!ring->intf)
return ret;
ret = gnttab_grant_foreign_access(dev->otherend_id,
virt_to_gfn(ring->intf), 0);
if (ret < 0)
goto out;
ring->ref = ret;
bytes = alloc_pages_exact(1UL << (order + XEN_PAGE_SHIFT),
GFP_KERNEL | __GFP_ZERO);
if (!bytes) {
ret = -ENOMEM;
goto out;
}
for (; i < (1 << order); i++) {
ret = gnttab_grant_foreign_access(
dev->otherend_id, virt_to_gfn(bytes) + i, 0);
if (ret < 0)
goto out;
ring->intf->ref[i] = ret;
}
ring->intf->ring_order = order;
ring->data.in = bytes;
ring->data.out = bytes + XEN_FLEX_RING_SIZE(order);
ret = xenbus_alloc_evtchn(dev, &ring->evtchn);
if (ret)
goto out;
ring->irq = bind_evtchn_to_irqhandler(ring->evtchn,
xen_9pfs_front_event_handler,
0, "xen_9pfs-frontend", ring);
if (ring->irq >= 0)
return 0;
xenbus_free_evtchn(dev, ring->evtchn);
ret = ring->irq;
out:
if (bytes) {
for (i--; i >= 0; i--)
gnttab_end_foreign_access(ring->intf->ref[i], NULL);
free_pages_exact(bytes, 1UL << (order + XEN_PAGE_SHIFT));
}
gnttab_end_foreign_access(ring->ref, NULL);
free_page((unsigned long)ring->intf);
return ret;
}
static int xen_9pfs_front_init(struct xenbus_device *dev)
{
int ret, i;
struct xenbus_transaction xbt;
struct xen_9pfs_front_priv *priv = dev_get_drvdata(&dev->dev);
char *versions, *v;
unsigned int max_rings, max_ring_order, len = 0;
versions = xenbus_read(XBT_NIL, dev->otherend, "versions", &len);
if (IS_ERR(versions))
return PTR_ERR(versions);
for (v = versions; *v; v++) {
if (simple_strtoul(v, &v, 10) == 1) {
v = NULL;
break;
}
}
if (v) {
kfree(versions);
return -EINVAL;
}
kfree(versions);
max_rings = xenbus_read_unsigned(dev->otherend, "max-rings", 0);
if (max_rings < XEN_9PFS_NUM_RINGS)
return -EINVAL;
max_ring_order = xenbus_read_unsigned(dev->otherend,
"max-ring-page-order", 0);
if (max_ring_order > XEN_9PFS_RING_ORDER)
max_ring_order = XEN_9PFS_RING_ORDER;
if (p9_xen_trans.maxsize > XEN_FLEX_RING_SIZE(max_ring_order))
p9_xen_trans.maxsize = XEN_FLEX_RING_SIZE(max_ring_order) / 2;
priv->rings = kcalloc(XEN_9PFS_NUM_RINGS, sizeof(*priv->rings),
GFP_KERNEL);
if (!priv->rings) {
kfree(priv);
return -ENOMEM;
}
for (i = 0; i < XEN_9PFS_NUM_RINGS; i++) {
priv->rings[i].priv = priv;
ret = xen_9pfs_front_alloc_dataring(dev, &priv->rings[i],
max_ring_order);
if (ret < 0)
goto error;
}
again:
ret = xenbus_transaction_start(&xbt);
if (ret) {
xenbus_dev_fatal(dev, ret, "starting transaction");
goto error;
}
ret = xenbus_printf(xbt, dev->nodename, "version", "%u", 1);
if (ret)
goto error_xenbus;
ret = xenbus_printf(xbt, dev->nodename, "num-rings", "%u",
XEN_9PFS_NUM_RINGS);
if (ret)
goto error_xenbus;
for (i = 0; i < XEN_9PFS_NUM_RINGS; i++) {
char str[16];
BUILD_BUG_ON(XEN_9PFS_NUM_RINGS > 9);
sprintf(str, "ring-ref%d", i);
ret = xenbus_printf(xbt, dev->nodename, str, "%d",
priv->rings[i].ref);
if (ret)
goto error_xenbus;
sprintf(str, "event-channel-%d", i);
ret = xenbus_printf(xbt, dev->nodename, str, "%u",
priv->rings[i].evtchn);
if (ret)
goto error_xenbus;
}
priv->tag = xenbus_read(xbt, dev->nodename, "tag", NULL);
if (IS_ERR(priv->tag)) {
ret = PTR_ERR(priv->tag);
goto error_xenbus;
}
ret = xenbus_transaction_end(xbt, 0);
if (ret) {
if (ret == -EAGAIN)
goto again;
xenbus_dev_fatal(dev, ret, "completing transaction");
goto error;
}
return 0;
error_xenbus:
xenbus_transaction_end(xbt, 1);
xenbus_dev_fatal(dev, ret, "writing xenstore");
error:
xen_9pfs_front_free(priv);
return ret;
}
static int xen_9pfs_front_probe(struct xenbus_device *dev,
const struct xenbus_device_id *id)
{
struct xen_9pfs_front_priv *priv = NULL;
priv = kzalloc(sizeof(*priv), GFP_KERNEL);
if (!priv)
return -ENOMEM;
priv->dev = dev;
dev_set_drvdata(&dev->dev, priv);
write_lock(&xen_9pfs_lock);
list_add_tail(&priv->list, &xen_9pfs_devs);
write_unlock(&xen_9pfs_lock);
return 0;
}
static int xen_9pfs_front_resume(struct xenbus_device *dev)
{
dev_warn(&dev->dev, "suspend/resume unsupported\n");
return 0;
}
static void xen_9pfs_front_changed(struct xenbus_device *dev,
enum xenbus_state backend_state)
{
switch (backend_state) {
case XenbusStateReconfiguring:
case XenbusStateReconfigured:
case XenbusStateInitialising:
case XenbusStateInitialised:
case XenbusStateUnknown:
break;
case XenbusStateInitWait:
if (!xen_9pfs_front_init(dev))
xenbus_switch_state(dev, XenbusStateInitialised);
break;
case XenbusStateConnected:
xenbus_switch_state(dev, XenbusStateConnected);
break;
case XenbusStateClosed:
if (dev->state == XenbusStateClosed)
break;
fallthrough; /* Missed the backend's CLOSING state */
case XenbusStateClosing:
xenbus_frontend_closed(dev);
break;
}
}
static struct xenbus_driver xen_9pfs_front_driver = {
.ids = xen_9pfs_front_ids,
.probe = xen_9pfs_front_probe,
.remove = xen_9pfs_front_remove,
.resume = xen_9pfs_front_resume,
.otherend_changed = xen_9pfs_front_changed,
};
static int __init p9_trans_xen_init(void)
{
int rc;
if (!xen_domain())
return -ENODEV;
pr_info("Initialising Xen transport for 9pfs\n");
v9fs_register_trans(&p9_xen_trans);
rc = xenbus_register_frontend(&xen_9pfs_front_driver);
if (rc)
v9fs_unregister_trans(&p9_xen_trans);
return rc;
}
module_init(p9_trans_xen_init);
MODULE_ALIAS_9P("xen");
static void __exit p9_trans_xen_exit(void)
{
v9fs_unregister_trans(&p9_xen_trans);
return xenbus_unregister_driver(&xen_9pfs_front_driver);
}
module_exit(p9_trans_xen_exit);
MODULE_ALIAS("xen:9pfs");
MODULE_AUTHOR("Stefano Stabellini <stefano@aporeto.com>");
MODULE_DESCRIPTION("Xen Transport for 9P");
MODULE_LICENSE("GPL");