#include <xen/hvm/params.h>
#include <mini-os/spinlock.h>
#include <mini-os/xmalloc.h>
+#include <mini-os/semaphore.h>
#define min(x,y) ({ \
typeof(x) tmpx = (x); \
static struct xenstore_domain_interface *xenstore_buf;
static DECLARE_WAIT_QUEUE_HEAD(xb_waitq);
DECLARE_WAIT_QUEUE_HEAD(xenbus_watch_queue);
+static __DECLARE_SEMAPHORE_GENERIC(xb_write_sem, 1);
xenbus_event_queue xenbus_events;
static struct watch {
}
+static void xenbus_read_data(char *buf, unsigned int len)
+{
+ unsigned int off = 0;
+ unsigned int prod, cons;
+ unsigned int size;
+
+ while (off != len)
+ {
+ wait_event(xb_waitq, xenstore_buf->rsp_prod != xenstore_buf->rsp_cons);
+
+ prod = xenstore_buf->rsp_prod;
+ cons = xenstore_buf->rsp_cons;
+ DEBUG("Rsp_cons %d, rsp_prod %d.\n", cons, prod);
+ size = min(len - off, prod - cons);
+
+ rmb(); /* Make sure data read from ring is ordered with rsp_prod. */
+ memcpy_from_ring(xenstore_buf->rsp, buf + off,
+ MASK_XENSTORE_IDX(cons), size);
+ off += size;
+ mb(); /* memcpy() and rsp_cons update must not be reordered. */
+ xenstore_buf->rsp_cons += size;
+ mb(); /* rsp_cons must be visible before we look at rsp_prod. */
+ if (xenstore_buf->rsp_prod - cons >= XENSTORE_RING_SIZE)
+ notify_remote_via_evtchn(xenbus_evtchn);
+ }
+}
+
static void xenbus_thread_func(void *ign)
{
struct xsd_sockmsg msg;
- unsigned prod = xenstore_buf->rsp_prod;
+ char *data;
for (;;) {
- wait_event(xb_waitq, prod != xenstore_buf->rsp_prod);
- while (1) {
- prod = xenstore_buf->rsp_prod;
- DEBUG("Rsp_cons %d, rsp_prod %d.\n", xenstore_buf->rsp_cons,
- xenstore_buf->rsp_prod);
- if (xenstore_buf->rsp_prod - xenstore_buf->rsp_cons < sizeof(msg))
- break;
- rmb();
- memcpy_from_ring(xenstore_buf->rsp, &msg,
- MASK_XENSTORE_IDX(xenstore_buf->rsp_cons),
- sizeof(msg));
- DEBUG("Msg len %d, %d avail, id %d.\n", msg.len + sizeof(msg),
- xenstore_buf->rsp_prod - xenstore_buf->rsp_cons, msg.req_id);
-
- if (xenstore_buf->rsp_prod - xenstore_buf->rsp_cons <
- sizeof(msg) + msg.len)
- break;
-
- DEBUG("Message is good.\n");
-
- if (msg.type == XS_WATCH_EVENT) {
- struct xenbus_event *event = malloc(sizeof(*event) + msg.len);
- xenbus_event_queue *events = NULL;
- char *data = (char*)event + sizeof(*event);
- struct watch *watch;
-
- memcpy_from_ring(xenstore_buf->rsp, data,
- MASK_XENSTORE_IDX(xenstore_buf->rsp_cons + sizeof(msg)),
- msg.len);
-
- event->path = data;
- event->token = event->path + strlen(event->path) + 1;
-
- mb();
- xenstore_buf->rsp_cons += msg.len + sizeof(msg);
-
- for (watch = watches; watch; watch = watch->next)
- if (!strcmp(watch->token, event->token)) {
- events = watch->events;
- break;
- }
-
- if (events) {
- event->next = *events;
- *events = event;
- wake_up(&xenbus_watch_queue);
- } else {
- printk("unexpected watch token %s\n", event->token);
- free(event);
+ xenbus_read_data((char *)&msg, sizeof(msg));
+ DEBUG("Msg len %d, %d avail, id %d.\n", msg.len + sizeof(msg),
+ xenstore_buf->rsp_prod - xenstore_buf->rsp_cons, msg.req_id);
+
+ if (msg.len > XENSTORE_PAYLOAD_MAX) {
+ printk("Xenstore violates protocol, message longer than allowed.\n");
+ return;
+ }
+
+ if (msg.type == XS_WATCH_EVENT) {
+ struct xenbus_event *event = malloc(sizeof(*event) + msg.len);
+ xenbus_event_queue *events = NULL;
+ struct watch *watch;
+ char *c;
+ int zeroes = 0;
+
+ data = (char*)event + sizeof(*event);
+ xenbus_read_data(data, msg.len);
+
+ for (c = data; c < data + msg.len; c++)
+ if (!*c)
+ zeroes++;
+ if (zeroes != 2) {
+ printk("Xenstore: illegal watch event data\n");
+ free(event);
+ continue;
+ }
+
+ event->path = data;
+ event->token = event->path + strlen(event->path) + 1;
+
+ for (watch = watches; watch; watch = watch->next)
+ if (!strcmp(watch->token, event->token)) {
+ events = watch->events;
+ break;
}
+
+ if (events) {
+ event->next = *events;
+ *events = event;
+ wake_up(&xenbus_watch_queue);
} else {
- req_info[msg.req_id].reply = malloc(sizeof(msg) + msg.len);
- memcpy_from_ring(xenstore_buf->rsp, req_info[msg.req_id].reply,
- MASK_XENSTORE_IDX(xenstore_buf->rsp_cons),
- msg.len + sizeof(msg));
- mb();
- xenstore_buf->rsp_cons += msg.len + sizeof(msg);
- wake_up(&req_info[msg.req_id].waitq);
+ printk("Xenstore: unexpected watch token %s\n", event->token);
+ free(event);
}
- wmb();
- notify_remote_via_evtchn(xenbus_evtchn);
+ continue;
}
+
+ data = malloc(sizeof(msg) + msg.len);
+ memcpy(data, &msg, sizeof(msg));
+ xenbus_read_data(data + sizeof(msg), msg.len);
+
+ if (msg.req_id >= NR_REQS || !req_info[msg.req_id].in_use) {
+ printk("Xenstore: illegal request id %d\n", msg.req_id);
+ free(data);
+ continue;
+ }
+
+ DEBUG("Message is good.\n");
+
+ req_info[msg.req_id].reply = data;
+
+ wake_up(&req_info[msg.req_id].waitq);
}
}
cur_req = &header_req;
- BUG_ON(len > XENSTORE_RING_SIZE);
- /* Wait for the ring to drain to the point where we can send the
- message. */
- prod = xenstore_buf->req_prod;
- if (prod + len - xenstore_buf->req_cons > XENSTORE_RING_SIZE)
- {
- /* Wait for there to be space on the ring */
- DEBUG("prod %d, len %d, cons %d, size %d; waiting.\n",
- prod, len, xenstore_buf->req_cons, XENSTORE_RING_SIZE);
- wait_event(xb_waitq,
- xenstore_buf->req_prod + len - xenstore_buf->req_cons <=
- XENSTORE_RING_SIZE);
- DEBUG("Back from wait.\n");
- prod = xenstore_buf->req_prod;
- }
+ BUG_ON(len > XENSTORE_PAYLOAD_MAX);
+
+ /* Make sure we are the only thread trying to write. */
+ down(&xb_write_sem);
- /* We're now guaranteed to be able to send the message without
- overflowing the ring. Do so. */
+ /* Send the message in chunks using free ring space when available. */
total_off = 0;
req_off = 0;
- while (total_off < len)
+ while (total_off < len)
{
+ prod = xenstore_buf->req_prod;
+ if (prod - xenstore_buf->req_cons >= XENSTORE_RING_SIZE)
+ {
+ /* Send evtchn to notify remote */
+ notify_remote_via_evtchn(xenbus_evtchn);
+
+ /* Wait for there to be space on the ring */
+ DEBUG("prod %d, len %d, cons %d, size %d; waiting.\n", prod,
+ len - total_off, xenstore_buf->req_cons, XENSTORE_RING_SIZE);
+ wait_event(xb_waitq,
+ prod - xenstore_buf->req_cons < XENSTORE_RING_SIZE);
+ DEBUG("Back from wait.\n");
+ }
+
this_chunk = min(cur_req->len - req_off,
- XENSTORE_RING_SIZE - MASK_XENSTORE_IDX(prod));
+ XENSTORE_RING_SIZE - MASK_XENSTORE_IDX(prod));
+ this_chunk = min(this_chunk,
+ xenstore_buf->req_cons + XENSTORE_RING_SIZE - prod);
memcpy((char *)xenstore_buf->req + MASK_XENSTORE_IDX(prod),
- (char *)cur_req->data + req_off, this_chunk);
+ (char *)cur_req->data + req_off, this_chunk);
prod += this_chunk;
req_off += this_chunk;
total_off += this_chunk;
- if (req_off == cur_req->len)
+ if (req_off == cur_req->len)
{
req_off = 0;
if (cur_req == &header_req)
else
cur_req++;
}
+
+ /* Remote must see entire message before updating indexes */
+ wmb();
+ xenstore_buf->req_prod = prod;
}
+ /* Send evtchn to notify remote */
+ notify_remote_via_evtchn(xenbus_evtchn);
+
DEBUG("Complete main loop of xb_write.\n");
BUG_ON(req_off != 0);
BUG_ON(total_off != len);
- BUG_ON(prod > xenstore_buf->req_cons + XENSTORE_RING_SIZE);
- /* Remote must see entire message before updating indexes */
- wmb();
-
- xenstore_buf->req_prod += len;
-
- /* Send evtchn to notify remote */
- notify_remote_via_evtchn(xenbus_evtchn);
+ up(&xb_write_sem);
}
/* Send a mesasge to xenbus, in the same fashion as xb_write, and
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