diff --git a/drivers/xen/xenbus/xenbus.h b/drivers/xen/xenbus/xenbus.h
index 51995276f549..149c5e7efc89 100644
--- a/drivers/xen/xenbus/xenbus.h
+++ b/drivers/xen/xenbus/xenbus.h
@@ -32,6 +32,10 @@
#ifndef _XENBUS_XENBUS_H
#define _XENBUS_XENBUS_H
+#include <linux/mutex.h>
+#include <linux/uio.h>
+#include <xen/xenbus.h>
+
#define XEN_BUS_ID_SIZE 20
struct xen_bus_type {
@@ -52,16 +56,49 @@ enum xenstore_init {
XS_LOCAL,
};
+struct xs_watch_event {
+ struct list_head list;
+ unsigned int len;
+ struct xenbus_watch *handle;
+ const char *path;
+ const char *token;
+ char body[];
+};
+
+enum xb_req_state {
+ xb_req_state_queued,
+ xb_req_state_wait_reply,
+ xb_req_state_got_reply,
+ xb_req_state_aborted
+};
+
+struct xb_req_data {
+ struct list_head list;
+ wait_queue_head_t wq;
+ struct xsd_sockmsg msg;
+ enum xsd_sockmsg_type type;
+ char *body;
+ const struct kvec *vec;
+ int num_vecs;
+ int err;
+ enum xb_req_state state;
+ void (*cb)(struct xb_req_data *);
+ void *par;
+};
+
extern enum xenstore_init xen_store_domain_type;
extern const struct attribute_group *xenbus_dev_groups[];
+extern struct mutex xs_response_mutex;
+extern struct list_head xs_reply_list;
+extern struct list_head xb_write_list;
+extern wait_queue_head_t xb_waitq;
+extern struct mutex xb_write_mutex;
int xs_init(void);
int xb_init_comms(void);
void xb_deinit_comms(void);
-int xb_write(const void *data, unsigned int len);
-int xb_read(void *data, unsigned int len);
-int xb_data_to_read(void);
-int xb_wait_for_data_to_read(void);
+int xs_watch_msg(struct xs_watch_event *event);
+void xs_request_exit(struct xb_req_data *req);
int xenbus_match(struct device *_dev, struct device_driver *_drv);
int xenbus_dev_probe(struct device *_dev);
@@ -92,6 +129,7 @@ int xenbus_read_otherend_details(struct xenbus_device *xendev,
void xenbus_ring_ops_init(void);
-void *xenbus_dev_request_and_reply(struct xsd_sockmsg *msg);
+int xenbus_dev_request_and_reply(struct xsd_sockmsg *msg, void *par);
+void xenbus_dev_queue_reply(struct xb_req_data *req);
#endif
diff --git a/drivers/xen/xenbus/xenbus_comms.c b/drivers/xen/xenbus/xenbus_comms.c
index c21ec02643e1..856ada5d39c9 100644
--- a/drivers/xen/xenbus/xenbus_comms.c
+++ b/drivers/xen/xenbus/xenbus_comms.c
@@ -34,6 +34,7 @@
#include <linux/wait.h>
#include <linux/interrupt.h>
+#include <linux/kthread.h>
#include <linux/sched.h>
#include <linux/err.h>
#include <xen/xenbus.h>
@@ -42,11 +43,22 @@
#include <xen/page.h>
#include "xenbus.h"
+/* A list of replies. Currently only one will ever be outstanding. */
+LIST_HEAD(xs_reply_list);
+
+/* A list of write requests. */
+LIST_HEAD(xb_write_list);
+DECLARE_WAIT_QUEUE_HEAD(xb_waitq);
+DEFINE_MUTEX(xb_write_mutex);
+
+/* Protect xenbus reader thread against save/restore. */
+DEFINE_MUTEX(xs_response_mutex);
+
static int xenbus_irq;
+static struct task_struct *xenbus_task;
static DECLARE_WORK(probe_work, xenbus_probe);
-static DECLARE_WAIT_QUEUE_HEAD(xb_waitq);
static irqreturn_t wake_waiting(int irq, void *unused)
{
@@ -84,30 +96,31 @@ static const void *get_input_chunk(XENSTORE_RING_IDX cons,
return buf + MASK_XENSTORE_IDX(cons);
}
+static int xb_data_to_write(void)
+{
+ struct xenstore_domain_interface *intf = xen_store_interface;
+
+ return (intf->req_prod - intf->req_cons) != XENSTORE_RING_SIZE &&
+ !list_empty(&xb_write_list);
+}
+
/**
* xb_write - low level write
* @data: buffer to send
* @len: length of buffer
*
- * Returns 0 on success, error otherwise.
+ * Returns number of bytes written or -err.
*/
-int xb_write(const void *data, unsigned len)
+static int xb_write(const void *data, unsigned int len)
{
struct xenstore_domain_interface *intf = xen_store_interface;
XENSTORE_RING_IDX cons, prod;
- int rc;
+ unsigned int bytes = 0;
while (len != 0) {
void *dst;
unsigned int avail;
- rc = wait_event_interruptible(
- xb_waitq,
- (intf->req_prod - intf->req_cons) !=
- XENSTORE_RING_SIZE);
- if (rc < 0)
- return rc;
-
/* Read indexes, then verify. */
cons = intf->req_cons;
prod = intf->req_prod;
@@ -115,6 +128,11 @@ int xb_write(const void *data, unsigned len)
intf->req_cons = intf->req_prod = 0;
return -EIO;
}
+ if (!xb_data_to_write())
+ return bytes;
+
+ /* Must write data /after/ reading the consumer index. */
+ virt_mb();
dst = get_output_chunk(cons, prod, intf->req, &avail);
if (avail == 0)
@@ -122,52 +140,45 @@ int xb_write(const void *data, unsigned len)
if (avail > len)
avail = len;
- /* Must write data /after/ reading the consumer index. */
- virt_mb();
-
memcpy(dst, data, avail);
data += avail;
len -= avail;
+ bytes += avail;
/* Other side must not see new producer until data is there. */
virt_wmb();
intf->req_prod += avail;
/* Implies mb(): other side will see the updated producer. */
- notify_remote_via_evtchn(xen_store_evtchn);
+ if (prod <= intf->req_cons)
+ notify_remote_via_evtchn(xen_store_evtchn);
}
- return 0;
+ return bytes;
}
-int xb_data_to_read(void)
+static int xb_data_to_read(void)
{
struct xenstore_domain_interface *intf = xen_store_interface;
return (intf->rsp_cons != intf->rsp_prod);
}
-int xb_wait_for_data_to_read(void)
-{
- return wait_event_interruptible(xb_waitq, xb_data_to_read());
-}
-
-int xb_read(void *data, unsigned len)
+static int xb_read(void *data, unsigned int len)
{
struct xenstore_domain_interface *intf = xen_store_interface;
XENSTORE_RING_IDX cons, prod;
- int rc;
+ unsigned int bytes = 0;
while (len != 0) {
unsigned int avail;
const char *src;
- rc = xb_wait_for_data_to_read();
- if (rc < 0)
- return rc;
-
/* Read indexes, then verify. */
cons = intf->rsp_cons;
prod = intf->rsp_prod;
+ if (cons == prod)
+ return bytes;
+
if (!check_indexes(cons, prod)) {
intf->rsp_cons = intf->rsp_prod = 0;
return -EIO;
@@ -185,17 +196,243 @@ int xb_read(void *data, unsigned len)
memcpy(data, src, avail);
data += avail;
len -= avail;
+ bytes += avail;
/* Other side must not see free space until we've copied out */
virt_mb();
intf->rsp_cons += avail;
- pr_debug("Finished read of %i bytes (%i to go)\n", avail, len);
-
/* Implies mb(): other side will see the updated consumer. */
- notify_remote_via_evtchn(xen_store_evtchn);
+ if (intf->rsp_prod - cons >= XENSTORE_RING_SIZE)
+ notify_remote_via_evtchn(xen_store_evtchn);
}
+ return bytes;
+}
+
+static int process_msg(void)
+{
+ static struct {
+ struct xsd_sockmsg msg;
+ char *body;
+ union {
+ void *alloc;
+ struct xs_watch_event *watch;
+ };
+ bool in_msg;
+ bool in_hdr;
+ unsigned int read;
+ } state;
+ struct xb_req_data *req;
+ int err;
+ unsigned int len;
+
+ if (!state.in_msg) {
+ state.in_msg = true;
+ state.in_hdr = true;
+ state.read = 0;
+
+ /*
+ * We must disallow save/restore while reading a message.
+ * A partial read across s/r leaves us out of sync with
+ * xenstored.
+ * xs_response_mutex is locked as long as we are processing one
+ * message. state.in_msg will be true as long as we are holding
+ * the lock here.
+ */
+ mutex_lock(&xs_response_mutex);
+
+ if (!xb_data_to_read()) {
+ /* We raced with save/restore: pending data 'gone'. */
+ mutex_unlock(&xs_response_mutex);
+ state.in_msg = false;
+ return 0;
+ }
+ }
+
+ if (state.in_hdr) {
+ if (state.read != sizeof(state.msg)) {
+ err = xb_read((void *)&state.msg + state.read,
+ sizeof(state.msg) - state.read);
+ if (err < 0)
+ goto out;
+ state.read += err;
+ if (state.read != sizeof(state.msg))
+ return 0;
+ if (state.msg.len > XENSTORE_PAYLOAD_MAX) {
+ err = -EINVAL;
+ goto out;
+ }
+ }
+
+ len = state.msg.len + 1;
+ if (state.msg.type == XS_WATCH_EVENT)
+ len += sizeof(*state.watch);
+
+ state.alloc = kmalloc(len, GFP_NOIO | __GFP_HIGH);
+ if (!state.alloc)
+ return -ENOMEM;
+
+ if (state.msg.type == XS_WATCH_EVENT)
+ state.body = state.watch->body;
+ else
+ state.body = state.alloc;
+ state.in_hdr = false;
+ state.read = 0;
+ }
+
+ err = xb_read(state.body + state.read, state.msg.len - state.read);
+ if (err < 0)
+ goto out;
+
+ state.read += err;
+ if (state.read != state.msg.len)
+ return 0;
+
+ state.body[state.msg.len] = '\0';
+
+ if (state.msg.type == XS_WATCH_EVENT) {
+ state.watch->len = state.msg.len;
+ err = xs_watch_msg(state.watch);
+ } else {
+ err = -ENOENT;
+ mutex_lock(&xb_write_mutex);
+ list_for_each_entry(req, &xs_reply_list, list) {
+ if (req->msg.req_id == state.msg.req_id) {
+ if (req->state == xb_req_state_wait_reply) {
+ req->msg.type = state.msg.type;
+ req->msg.len = state.msg.len;
+ req->body = state.body;
+ req->state = xb_req_state_got_reply;
+ list_del(&req->list);
+ req->cb(req);
+ } else {
+ list_del(&req->list);
+ kfree(req);
+ }
+ err = 0;
+ break;
+ }
+ }
+ mutex_unlock(&xb_write_mutex);
+ if (err)
+ goto out;
+ }
+
+ mutex_unlock(&xs_response_mutex);
+
+ state.in_msg = false;
+ state.alloc = NULL;
+ return err;
+
+ out:
+ mutex_unlock(&xs_response_mutex);
+ state.in_msg = false;
+ kfree(state.alloc);
+ state.alloc = NULL;
+ return err;
+}
+
+static int process_writes(void)
+{
+ static struct {
+ struct xb_req_data *req;
+ int idx;
+ unsigned int written;
+ } state;
+ void *base;
+ unsigned int len;
+ int err = 0;
+
+ if (!xb_data_to_write())
+ return 0;
+
+ mutex_lock(&xb_write_mutex);
+
+ if (!state.req) {
+ state.req = list_first_entry(&xb_write_list,
+ struct xb_req_data, list);
+ state.idx = -1;
+ state.written = 0;
+ }
+
+ if (state.req->state == xb_req_state_aborted)
+ goto out_err;
+
+ while (state.idx < state.req->num_vecs) {
+ if (state.idx < 0) {
+ base = &state.req->msg;
+ len = sizeof(state.req->msg);
+ } else {
+ base = state.req->vec[state.idx].iov_base;
+ len = state.req->vec[state.idx].iov_len;
+ }
+ err = xb_write(base + state.written, len - state.written);
+ if (err < 0)
+ goto out_err;
+ state.written += err;
+ if (state.written != len)
+ goto out;
+
+ state.idx++;
+ state.written = 0;
+ }
+
+ list_del(&state.req->list);
+ state.req->state = xb_req_state_wait_reply;
+ list_add_tail(&state.req->list, &xs_reply_list);
+ state.req = NULL;
+
+ out:
+ mutex_unlock(&xb_write_mutex);
+
+ return 0;
+
+ out_err:
+ state.req->msg.type = XS_ERROR;
+ state.req->err = err;
+ list_del(&state.req->list);
+ if (state.req->state == xb_req_state_aborted)
+ kfree(state.req);
+ else {
+ state.req->state = xb_req_state_got_reply;
+ wake_up(&state.req->wq);
+ }
+
+ mutex_unlock(&xb_write_mutex);
+
+ state.req = NULL;
+
+ return err;
+}
+
+static int xb_thread_work(void)
+{
+ return xb_data_to_read() || xb_data_to_write();
+}
+
+static int xenbus_thread(void *unused)
+{
+ int err;
+
+ while (!kthread_should_stop()) {
+ if (wait_event_interruptible(xb_waitq, xb_thread_work()))
+ continue;
+
+ err = process_msg();
+ if (err == -ENOMEM)
+ schedule();
+ else if (err)
+ pr_warn_ratelimited("error %d while reading message\n",
+ err);
+
+ err = process_writes();
+ if (err)
+ pr_warn_ratelimited("error %d while writing message\n",
+ err);
+ }
+
+ xenbus_task = NULL;
return 0;
}
@@ -223,6 +460,7 @@ int xb_init_comms(void)
rebind_evtchn_irq(xen_store_evtchn, xenbus_irq);
} else {
int err;
+
err = bind_evtchn_to_irqhandler(xen_store_evtchn, wake_waiting,
0, "xenbus", &xb_waitq);
if (err < 0) {
@@ -231,6 +469,13 @@ int xb_init_comms(void)
}
xenbus_irq = err;
+
+ if (!xenbus_task) {
+ xenbus_task = kthread_run(xenbus_thread, NULL,
+ "xenbus");
+ if (IS_ERR(xenbus_task))
+ return PTR_ERR(xenbus_task);
+ }
}
return 0;
diff --git a/drivers/xen/xenbus/xenbus_dev_frontend.c b/drivers/xen/xenbus/xenbus_dev_frontend.c
index e4b984777507..4d343eed08f5 100644
--- a/drivers/xen/xenbus/xenbus_dev_frontend.c
+++ b/drivers/xen/xenbus/xenbus_dev_frontend.c
@@ -113,6 +113,7 @@ struct xenbus_file_priv {
struct list_head read_buffers;
wait_queue_head_t read_waitq;
+ struct kref kref;
};
/* Read out any raw xenbus messages queued up. */
@@ -297,6 +298,107 @@ static void watch_fired(struct xenbus_watch *watch,
mutex_unlock(&adap->dev_data->reply_mutex);
}
+static void xenbus_file_free(struct kref *kref)
+{
+ struct xenbus_file_priv *u;
+ struct xenbus_transaction_holder *trans, *tmp;
+ struct watch_adapter *watch, *tmp_watch;
+ struct read_buffer *rb, *tmp_rb;
+
+ u = container_of(kref, struct xenbus_file_priv, kref);
+
+ /*
+ * No need for locking here because there are no other users,
+ * by definition.
+ */
+
+ list_for_each_entry_safe(trans, tmp, &u->transactions, list) {
+ xenbus_transaction_end(trans->handle, 1);
+ list_del(&trans->list);
+ kfree(trans);
+ }
+
+ list_for_each_entry_safe(watch, tmp_watch, &u->watches, list) {
+ unregister_xenbus_watch(&watch->watch);
+ list_del(&watch->list);
+ free_watch_adapter(watch);
+ }
+
+ list_for_each_entry_safe(rb, tmp_rb, &u->read_buffers, list) {
+ list_del(&rb->list);
+ kfree(rb);
+ }
+ kfree(u);
+}
+
+static struct xenbus_transaction_holder *xenbus_get_transaction(
+ struct xenbus_file_priv *u, uint32_t tx_id)
+{
+ struct xenbus_transaction_holder *trans;
+
+ list_for_each_entry(trans, &u->transactions, list)
+ if (trans->handle.id == tx_id)
+ return trans;
+
+ return NULL;
+}
+
+void xenbus_dev_queue_reply(struct xb_req_data *req)
+{
+ struct xenbus_file_priv *u = req->par;
+ struct xenbus_transaction_holder *trans = NULL;
+ int rc;
+ LIST_HEAD(staging_q);
+
+ xs_request_exit(req);
+
+ mutex_lock(&u->msgbuffer_mutex);
+
+ if (req->type == XS_TRANSACTION_START) {
+ trans = xenbus_get_transaction(u, 0);
+ if (WARN_ON(!trans))
+ goto out;
+ if (req->msg.type == XS_ERROR) {
+ list_del(&trans->list);
+ kfree(trans);
+ } else {
+ rc = kstrtou32(req->body, 10, &trans->handle.id);
+ if (WARN_ON(rc))
+ goto out;
+ }
+ } else if (req->msg.type == XS_TRANSACTION_END) {
+ trans = xenbus_get_transaction(u, req->msg.tx_id);
+ if (WARN_ON(!trans))
+ goto out;
+ list_del(&trans->list);
+ kfree(trans);
+ }
+
+ mutex_unlock(&u->msgbuffer_mutex);
+
+ mutex_lock(&u->reply_mutex);
+ rc = queue_reply(&staging_q, &req->msg, sizeof(req->msg));
+ if (!rc)
+ rc = queue_reply(&staging_q, req->body, req->msg.len);
+ if (!rc) {
+ list_splice_tail(&staging_q, &u->read_buffers);
+ wake_up(&u->read_waitq);
+ } else {
+ queue_cleanup(&staging_q);
+ }
+ mutex_unlock(&u->reply_mutex);
+
+ kfree(req->body);
+ kfree(req);
+
+ kref_put(&u->kref, xenbus_file_free);
+
+ return;
+
+ out:
+ mutex_unlock(&u->msgbuffer_mutex);
+}
+
static int xenbus_command_reply(struct xenbus_file_priv *u,
unsigned int msg_type, const char *reply)
{
@@ -317,6 +419,9 @@ static int xenbus_command_reply(struct xenbus_file_priv *u,
wake_up(&u->read_waitq);
mutex_unlock(&u->reply_mutex);
+ if (!rc)
+ kref_put(&u->kref, xenbus_file_free);
+
return rc;
}
@@ -324,57 +429,22 @@ static int xenbus_write_transaction(unsigned msg_type,
struct xenbus_file_priv *u)
{
int rc;
- void *reply;
struct xenbus_transaction_holder *trans = NULL;
- LIST_HEAD(staging_q);
if (msg_type == XS_TRANSACTION_START) {
- trans = kmalloc(sizeof(*trans), GFP_KERNEL);
+ trans = kzalloc(sizeof(*trans), GFP_KERNEL);
if (!trans) {
rc = -ENOMEM;
goto out;
}
- } else if (u->u.msg.tx_id != 0) {
- list_for_each_entry(trans, &u->transactions, list)
- if (trans->handle.id == u->u.msg.tx_id)
- break;
- if (&trans->list == &u->transactions)
- return xenbus_command_reply(u, XS_ERROR, "ENOENT");
- }
+ list_add(&trans->list, &u->transactions);
+ } else if (u->u.msg.tx_id != 0 &&
+ !xenbus_get_transaction(u, u->u.msg.tx_id))
+ return xenbus_command_reply(u, XS_ERROR, "ENOENT");
- reply = xenbus_dev_request_and_reply(&u->u.msg);
- if (IS_ERR(reply)) {
- if (msg_type == XS_TRANSACTION_START)
- kfree(trans);
- rc = PTR_ERR(reply);
- goto out;
- }
-
- if (msg_type == XS_TRANSACTION_START) {
- if (u->u.msg.type == XS_ERROR)
- kfree(trans);
- else {
- trans->handle.id = simple_strtoul(reply, NULL, 0);
- list_add(&trans->list, &u->transactions);
- }
- } else if (u->u.msg.type == XS_TRANSACTION_END) {
- list_del(&trans->list);
+ rc = xenbus_dev_request_and_reply(&u->u.msg, u);
+ if (rc)
kfree(trans);
- }
-
- mutex_lock(&u->reply_mutex);
- rc = queue_reply(&staging_q, &u->u.msg, sizeof(u->u.msg));
- if (!rc)
- rc = queue_reply(&staging_q, reply, u->u.msg.len);
- if (!rc) {
- list_splice_tail(&staging_q, &u->read_buffers);
- wake_up(&u->read_waitq);
- } else {
- queue_cleanup(&staging_q);
- }
- mutex_unlock(&u->reply_mutex);
-
- kfree(reply);
out:
return rc;
@@ -506,6 +576,8 @@ static ssize_t xenbus_file_write(struct file *filp,
* OK, now we have a complete message. Do something with it.
*/
+ kref_get(&u->kref);
+
msg_type = u->u.msg.type;
switch (msg_type) {
@@ -520,8 +592,10 @@ static ssize_t xenbus_file_write(struct file *filp,
ret = xenbus_write_transaction(msg_type, u);
break;
}
- if (ret != 0)
+ if (ret != 0) {
rc = ret;
+ kref_put(&u->kref, xenbus_file_free);
+ }
/* Buffered message consumed */
u->len = 0;
@@ -546,6 +620,8 @@ static int xenbus_file_open(struct inode *inode, struct file *filp)
if (u == NULL)
return -ENOMEM;
+ kref_init(&u->kref);
+
INIT_LIST_HEAD(&u->transactions);
INIT_LIST_HEAD(&u->watches);
INIT_LIST_HEAD(&u->read_buffers);
@@ -562,32 +638,8 @@ static int xenbus_file_open(struct inode *inode, struct file *filp)
static int xenbus_file_release(struct inode *inode, struct file *filp)
{
struct xenbus_file_priv *u = filp->private_data;
- struct xenbus_transaction_holder *trans, *tmp;
- struct watch_adapter *watch, *tmp_watch;
- struct read_buffer *rb, *tmp_rb;
- /*
- * No need for locking here because there are no other users,
- * by definition.
- */
-
- list_for_each_entry_safe(trans, tmp, &u->transactions, list) {
- xenbus_transaction_end(trans->handle, 1);
- list_del(&trans->list);
- kfree(trans);
- }
-
- list_for_each_entry_safe(watch, tmp_watch, &u->watches, list) {
- unregister_xenbus_watch(&watch->watch);
- list_del(&watch->list);
- free_watch_adapter(watch);
- }
-
- list_for_each_entry_safe(rb, tmp_rb, &u->read_buffers, list) {
- list_del(&rb->list);
- kfree(rb);
- }
- kfree(u);
+ kref_put(&u->kref, xenbus_file_free);
return 0;
}
diff --git a/drivers/xen/xenbus/xenbus_xs.c b/drivers/xen/xenbus/xenbus_xs.c
index ebc768f44abe..e46080214955 100644
--- a/drivers/xen/xenbus/xenbus_xs.c
+++ b/drivers/xen/xenbus/xenbus_xs.c
@@ -43,6 +43,7 @@
#include <linux/slab.h>
#include <linux/fcntl.h>
#include <linux/kthread.h>
+#include <linux/reboot.h>
#include <linux/rwsem.h>
#include <linux/mutex.h>
#include <asm/xen/hypervisor.h>
@@ -50,61 +51,28 @@
#include <xen/xen.h>
#include "xenbus.h"
-struct xs_stored_msg {
- struct list_head list;
+/*
+ * Framework to protect suspend/resume handling against normal Xenstore
+ * message handling:
+ * During suspend/resume there must be no open transaction and no pending
+ * Xenstore request.
+ * New watch events happening in this time can be ignored by firing all watches
+ * after resume.
+ */
- struct xsd_sockmsg hdr;
+/* Lock protecting enter/exit critical region. */
+static DEFINE_SPINLOCK(xs_state_lock);
+/* Number of users in critical region (protected by xs_state_lock). */
+static unsigned int xs_state_users;
+/* Suspend handler waiting or already active (protected by xs_state_lock)? */
+static int xs_suspend_active;
+/* Unique Xenstore request id (protected by xs_state_lock). */
+static uint32_t xs_request_id;
- union {
- /* Queued replies. */
- struct {
- char *body;
- } reply;
-
- /* Queued watch events. */
- struct {
- struct xenbus_watch *handle;
- const char *path;
- const char *token;
- } watch;
- } u;
-};
-
-struct xs_handle {
- /* A list of replies. Currently only one will ever be outstanding. */
- struct list_head reply_list;
- spinlock_t reply_lock;
- wait_queue_head_t reply_waitq;
-
- /*
- * Mutex ordering: transaction_mutex -> watch_mutex -> request_mutex.
- * response_mutex is never taken simultaneously with the other three.
- *
- * transaction_mutex must be held before incrementing
- * transaction_count. The mutex is held when a suspend is in
- * progress to prevent new transactions starting.
- *
- * When decrementing transaction_count to zero the wait queue
- * should be woken up, the suspend code waits for count to
- * reach zero.
- */
-
- /* One request at a time. */
- struct mutex request_mutex;
-
- /* Protect xenbus reader thread against save/restore. */
- struct mutex response_mutex;
-
- /* Protect transactions against save/restore. */
- struct mutex transaction_mutex;
- atomic_t transaction_count;
- wait_queue_head_t transaction_wq;
-
- /* Protect watch (de)register against save/restore. */
- struct rw_semaphore watch_mutex;
-};
-
-static struct xs_handle xs_state;
+/* Wait queue for all callers waiting for critical region to become usable. */
+static DECLARE_WAIT_QUEUE_HEAD(xs_state_enter_wq);
+/* Wait queue for suspend handling waiting for critical region being empty. */
+static DECLARE_WAIT_QUEUE_HEAD(xs_state_exit_wq);
/* List of registered watches, and a lock to protect it. */
static LIST_HEAD(watches);
@@ -114,6 +82,9 @@ static DEFINE_SPINLOCK(watches_lock);
static LIST_HEAD(watch_events);
static DEFINE_SPINLOCK(watch_events_lock);
+/* Protect watch (de)register against save/restore. */
+static DECLARE_RWSEM(xs_watch_rwsem);
+
/*
* Details of the xenwatch callback kernel thread. The thread waits on the
* watch_events_waitq for work to do (queued on watch_events list). When it
@@ -124,6 +95,59 @@ static pid_t xenwatch_pid;
static DEFINE_MUTEX(xenwatch_mutex);
static DECLARE_WAIT_QUEUE_HEAD(watch_events_waitq);
+static void xs_suspend_enter(void)
+{
+ spin_lock(&xs_state_lock);
+ xs_suspend_active++;
+ spin_unlock(&xs_state_lock);
+ wait_event(xs_state_exit_wq, xs_state_users == 0);
+}
+
+static void xs_suspend_exit(void)
+{
+ spin_lock(&xs_state_lock);
+ xs_suspend_active--;
+ spin_unlock(&xs_state_lock);
+ wake_up_all(&xs_state_enter_wq);
+}
+
+static uint32_t xs_request_enter(struct xb_req_data *req)
+{
+ uint32_t rq_id;
+
+ req->type = req->msg.type;
+
+ spin_lock(&xs_state_lock);
+
+ while (!xs_state_users && xs_suspend_active) {
+ spin_unlock(&xs_state_lock);
+ wait_event(xs_state_enter_wq, xs_suspend_active == 0);
+ spin_lock(&xs_state_lock);
+ }
+
+ if (req->type == XS_TRANSACTION_START)
+ xs_state_users++;
+ xs_state_users++;
+ rq_id = xs_request_id++;
+
+ spin_unlock(&xs_state_lock);
+
+ return rq_id;
+}
+
+void xs_request_exit(struct xb_req_data *req)
+{
+ spin_lock(&xs_state_lock);
+ xs_state_users--;
+ if ((req->type == XS_TRANSACTION_START && req->msg.type == XS_ERROR) ||
+ req->type == XS_TRANSACTION_END)
+ xs_state_users--;
+ spin_unlock(&xs_state_lock);
+
+ if (xs_suspend_active && !xs_state_users)
+ wake_up(&xs_state_exit_wq);
+}
+
static int get_error(const char *errorstring)
{
unsigned int i;
@@ -161,21 +185,24 @@ static bool xenbus_ok(void)
}
return false;
}
-static void *read_reply(enum xsd_sockmsg_type *type, unsigned int *len)
+
+static bool test_reply(struct xb_req_data *req)
{
- struct xs_stored_msg *msg;
- char *body;
+ if (req->state == xb_req_state_got_reply || !xenbus_ok())
+ return true;
- spin_lock(&xs_state.reply_lock);
+ /* Make sure to reread req->state each time. */
+ barrier();
- while (list_empty(&xs_state.reply_list)) {
- spin_unlock(&xs_state.reply_lock);
- if (xenbus_ok())
- /* XXX FIXME: Avoid synchronous wait for response here. */
- wait_event_timeout(xs_state.reply_waitq,
- !list_empty(&xs_state.reply_list),
- msecs_to_jiffies(500));
- else {
+ return false;
+}
+
+static void *read_reply(struct xb_req_data *req)
+{
+ while (req->state != xb_req_state_got_reply) {
+ wait_event(req->wq, test_reply(req));
+
+ if (!xenbus_ok())
/*
* If we are in the process of being shut-down there is
* no point of trying to contact XenBus - it is either
@@ -183,77 +210,83 @@ static void *read_reply(enum xsd_sockmsg_type *type, unsigned int *len)
* has been killed or is unreachable.
*/
return ERR_PTR(-EIO);
- }
- spin_lock(&xs_state.reply_lock);
+ if (req->err)
+ return ERR_PTR(req->err);
+
}
- msg = list_entry(xs_state.reply_list.next,
- struct xs_stored_msg, list);
- list_del(&msg->list);
-
- spin_unlock(&xs_state.reply_lock);
-
- *type = msg->hdr.type;
- if (len)
- *len = msg->hdr.len;
- body = msg->u.reply.body;
-
- kfree(msg);
-
- return body;
+ return req->body;
}
-static void transaction_start(void)
+static void xs_send(struct xb_req_data *req, struct xsd_sockmsg *msg)
{
- mutex_lock(&xs_state.transaction_mutex);
- atomic_inc(&xs_state.transaction_count);
- mutex_unlock(&xs_state.transaction_mutex);
+ bool notify;
+
+ req->msg = *msg;
+ req->err = 0;
+ req->state = xb_req_state_queued;
+ init_waitqueue_head(&req->wq);
+
+ req->msg.req_id = xs_request_enter(req);
+
+ mutex_lock(&xb_write_mutex);
+ list_add_tail(&req->list, &xb_write_list);
+ notify = list_is_singular(&xb_write_list);
+ mutex_unlock(&xb_write_mutex);
+
+ if (notify)
+ wake_up(&xb_waitq);
}
-static void transaction_end(void)
-{
- if (atomic_dec_and_test(&xs_state.transaction_count))
- wake_up(&xs_state.transaction_wq);
-}
-
-static void transaction_suspend(void)
-{
- mutex_lock(&xs_state.transaction_mutex);
- wait_event(xs_state.transaction_wq,
- atomic_read(&xs_state.transaction_count) == 0);
-}
-
-static void transaction_resume(void)
-{
- mutex_unlock(&xs_state.transaction_mutex);
-}
-
-void *xenbus_dev_request_and_reply(struct xsd_sockmsg *msg)
+static void *xs_wait_for_reply(struct xb_req_data *req, struct xsd_sockmsg *msg)
{
void *ret;
- enum xsd_sockmsg_type type = msg->type;
- int err;
- if (type == XS_TRANSACTION_START)
- transaction_start();
+ ret = read_reply(req);
- mutex_lock(&xs_state.request_mutex);
+ xs_request_exit(req);
- err = xb_write(msg, sizeof(*msg) + msg->len);
- if (err) {
- msg->type = XS_ERROR;
- ret = ERR_PTR(err);
- } else
- ret = read_reply(&msg->type, &msg->len);
+ msg->type = req->msg.type;
+ msg->len = req->msg.len;
- mutex_unlock(&xs_state.request_mutex);
-
- if ((msg->type == XS_TRANSACTION_END) ||
- ((type == XS_TRANSACTION_START) && (msg->type == XS_ERROR)))
- transaction_end();
+ mutex_lock(&xb_write_mutex);
+ if (req->state == xb_req_state_queued ||
+ req->state == xb_req_state_wait_reply)
+ req->state = xb_req_state_aborted;
+ else
+ kfree(req);
+ mutex_unlock(&xb_write_mutex);
return ret;
}
+
+static void xs_wake_up(struct xb_req_data *req)
+{
+ wake_up(&req->wq);
+}
+
+int xenbus_dev_request_and_reply(struct xsd_sockmsg *msg, void *par)
+{
+ struct xb_req_data *req;
+ struct kvec *vec;
+
+ req = kmalloc(sizeof(*req) + sizeof(*vec), GFP_KERNEL);
+ if (!req)
+ return -ENOMEM;
+
+ vec = (struct kvec *)(req + 1);
+ vec->iov_len = msg->len;
+ vec->iov_base = msg + 1;
+
+ req->vec = vec;
+ req->num_vecs = 1;
+ req->cb = xenbus_dev_queue_reply;
+ req->par = par;
+
+ xs_send(req, msg);
+
+ return 0;
+}
EXPORT_SYMBOL(xenbus_dev_request_and_reply);
/* Send message to xs, get kmalloc'ed reply. ERR_PTR() on error. */
@@ -263,37 +296,31 @@ static void *xs_talkv(struct xenbus_transaction t,
unsigned int num_vecs,
unsigned int *len)
{
+ struct xb_req_data *req;
struct xsd_sockmsg msg;
void *ret = NULL;
unsigned int i;
int err;
+ req = kmalloc(sizeof(*req), GFP_NOIO | __GFP_HIGH);
+ if (!req)
+ return ERR_PTR(-ENOMEM);
+
+ req->vec = iovec;
+ req->num_vecs = num_vecs;
+ req->cb = xs_wake_up;
+
msg.tx_id = t.id;
- msg.req_id = 0;
msg.type = type;
msg.len = 0;
for (i = 0; i < num_vecs; i++)
msg.len += iovec[i].iov_len;
- mutex_lock(&xs_state.request_mutex);
+ xs_send(req, &msg);
- err = xb_write(&msg, sizeof(msg));
- if (err) {
- mutex_unlock(&xs_state.request_mutex);
- return ERR_PTR(err);
- }
-
- for (i = 0; i < num_vecs; i++) {
- err = xb_write(iovec[i].iov_base, iovec[i].iov_len);
- if (err) {
- mutex_unlock(&xs_state.request_mutex);
- return ERR_PTR(err);
- }
- }
-
- ret = read_reply(&msg.type, len);
-
- mutex_unlock(&xs_state.request_mutex);
+ ret = xs_wait_for_reply(req, &msg);
+ if (len)
+ *len = msg.len;
if (IS_ERR(ret))
return ret;
@@ -500,13 +527,9 @@ int xenbus_transaction_start(struct xenbus_transaction *t)
{
char *id_str;
- transaction_start();
-
id_str = xs_single(XBT_NIL, XS_TRANSACTION_START, "", NULL);
- if (IS_ERR(id_str)) {
- transaction_end();
+ if (IS_ERR(id_str))
return PTR_ERR(id_str);
- }
t->id = simple_strtoul(id_str, NULL, 0);
kfree(id_str);
@@ -520,18 +543,13 @@ EXPORT_SYMBOL_GPL(xenbus_transaction_start);
int xenbus_transaction_end(struct xenbus_transaction t, int abort)
{
char abortstr[2];
- int err;
if (abort)
strcpy(abortstr, "F");
else
strcpy(abortstr, "T");
- err = xs_error(xs_single(t, XS_TRANSACTION_END, abortstr, NULL));
-
- transaction_end();
-
- return err;
+ return xs_error(xs_single(t, XS_TRANSACTION_END, abortstr, NULL));
}
EXPORT_SYMBOL_GPL(xenbus_transaction_end);
@@ -664,6 +682,30 @@ static struct xenbus_watch *find_watch(const char *token)
return NULL;
}
+
+int xs_watch_msg(struct xs_watch_event *event)
+{
+ if (count_strings(event->body, event->len) != 2) {
+ kfree(event);
+ return -EINVAL;
+ }
+ event->path = (const char *)event->body;
+ event->token = (const char *)strchr(event->body, '\0') + 1;
+
+ spin_lock(&watches_lock);
+ event->handle = find_watch(event->token);
+ if (event->handle != NULL) {
+ spin_lock(&watch_events_lock);
+ list_add_tail(&event->list, &watch_events);
+ wake_up(&watch_events_waitq);
+ spin_unlock(&watch_events_lock);
+ } else
+ kfree(event);
+ spin_unlock(&watches_lock);
+
+ return 0;
+}
+
/*
* Certain older XenBus toolstack cannot handle reading values that are
* not populated. Some Xen 3.4 installation are incapable of doing this
@@ -712,7 +754,7 @@ int register_xenbus_watch(struct xenbus_watch *watch)
sprintf(token, "%lX", (long)watch);
- down_read(&xs_state.watch_mutex);
+ down_read(&xs_watch_rwsem);
spin_lock(&watches_lock);
BUG_ON(find_watch(token));
@@ -727,7 +769,7 @@ int register_xenbus_watch(struct xenbus_watch *watch)
spin_unlock(&watches_lock);
}
- up_read(&xs_state.watch_mutex);
+ up_read(&xs_watch_rwsem);
return err;
}
@@ -735,13 +777,13 @@ EXPORT_SYMBOL_GPL(register_xenbus_watch);
void unregister_xenbus_watch(struct xenbus_watch *watch)
{
- struct xs_stored_msg *msg, *tmp;
+ struct xs_watch_event *event, *tmp;
char token[sizeof(watch) * 2 + 1];
int err;
sprintf(token, "%lX", (long)watch);
- down_read(&xs_state.watch_mutex);
+ down_read(&xs_watch_rwsem);
spin_lock(&watches_lock);
BUG_ON(!find_watch(token));
@@ -752,7 +794,7 @@ void unregister_xenbus_watch(struct xenbus_watch *watch)
if (err)
pr_warn("Failed to release watch %s: %i\n", watch->node, err);
- up_read(&xs_state.watch_mutex);
+ up_read(&xs_watch_rwsem);
/* Make sure there are no callbacks running currently (unless
its us) */
@@ -761,12 +803,11 @@ void unregister_xenbus_watch(struct xenbus_watch *watch)
/* Cancel pending watch events. */
spin_lock(&watch_events_lock);
- list_for_each_entry_safe(msg, tmp, &watch_events, list) {
- if (msg->u.watch.handle != watch)
+ list_for_each_entry_safe(event, tmp, &watch_events, list) {
+ if (event->handle != watch)
continue;
- list_del(&msg->list);
- kfree(msg->u.watch.path);
- kfree(msg);
+ list_del(&event->list);
+ kfree(event);
}
spin_unlock(&watch_events_lock);
@@ -777,10 +818,10 @@ EXPORT_SYMBOL_GPL(unregister_xenbus_watch);
void xs_suspend(void)
{
- transaction_suspend();
- down_write(&xs_state.watch_mutex);
- mutex_lock(&xs_state.request_mutex);
- mutex_lock(&xs_state.response_mutex);
+ xs_suspend_enter();
+
+ down_write(&xs_watch_rwsem);
+ mutex_lock(&xs_response_mutex);
}
void xs_resume(void)
@@ -790,31 +831,31 @@ void xs_resume(void)
xb_init_comms();
- mutex_unlock(&xs_state.response_mutex);
- mutex_unlock(&xs_state.request_mutex);
- transaction_resume();
+ mutex_unlock(&xs_response_mutex);
- /* No need for watches_lock: the watch_mutex is sufficient. */
+ xs_suspend_exit();
+
+ /* No need for watches_lock: the xs_watch_rwsem is sufficient. */
list_for_each_entry(watch, &watches, list) {
sprintf(token, "%lX", (long)watch);
xs_watch(watch->node, token);
}
- up_write(&xs_state.watch_mutex);
+ up_write(&xs_watch_rwsem);
}
void xs_suspend_cancel(void)
{
- mutex_unlock(&xs_state.response_mutex);
- mutex_unlock(&xs_state.request_mutex);
- up_write(&xs_state.watch_mutex);
- mutex_unlock(&xs_state.transaction_mutex);
+ mutex_unlock(&xs_response_mutex);
+ up_write(&xs_watch_rwsem);
+
+ xs_suspend_exit();
}
static int xenwatch_thread(void *unused)
{
struct list_head *ent;
- struct xs_stored_msg *msg;
+ struct xs_watch_event *event;
for (;;) {
wait_event_interruptible(watch_events_waitq,
@@ -832,12 +873,10 @@ static int xenwatch_thread(void *unused)
spin_unlock(&watch_events_lock);
if (ent != &watch_events) {
- msg = list_entry(ent, struct xs_stored_msg, list);
- msg->u.watch.handle->callback(msg->u.watch.handle,
- msg->u.watch.path,
- msg->u.watch.token);
- kfree(msg->u.watch.path);
- kfree(msg);
+ event = list_entry(ent, struct xs_watch_event, list);
+ event->handle->callback(event->handle, event->path,
+ event->token);
+ kfree(event);
}
mutex_unlock(&xenwatch_mutex);
@@ -846,126 +885,37 @@ static int xenwatch_thread(void *unused)
return 0;
}
-static int process_msg(void)
+/*
+ * Wake up all threads waiting for a xenstore reply. In case of shutdown all
+ * pending replies will be marked as "aborted" in order to let the waiters
+ * return in spite of xenstore possibly no longer being able to reply. This
+ * will avoid blocking shutdown by a thread waiting for xenstore but being
+ * necessary for shutdown processing to proceed.
+ */
+static int xs_reboot_notify(struct notifier_block *nb,
+ unsigned long code, void *unused)
{
- struct xs_stored_msg *msg;
- char *body;
- int err;
+ struct xb_req_data *req;
- /*
- * We must disallow save/restore while reading a xenstore message.
- * A partial read across s/r leaves us out of sync with xenstored.
- */
- for (;;) {
- err = xb_wait_for_data_to_read();
- if (err)
- return err;
- mutex_lock(&xs_state.response_mutex);
- if (xb_data_to_read())
- break;
- /* We raced with save/restore: pending data 'disappeared'. */
- mutex_unlock(&xs_state.response_mutex);
- }
-
-
- msg = kmalloc(sizeof(*msg), GFP_NOIO | __GFP_HIGH);
- if (msg == NULL) {
- err = -ENOMEM;
- goto out;
- }
-
- err = xb_read(&msg->hdr, sizeof(msg->hdr));
- if (err) {
- kfree(msg);
- goto out;
- }
-
- if (msg->hdr.len > XENSTORE_PAYLOAD_MAX) {
- kfree(msg);
- err = -EINVAL;
- goto out;
- }
-
- body = kmalloc(msg->hdr.len + 1, GFP_NOIO | __GFP_HIGH);
- if (body == NULL) {
- kfree(msg);
- err = -ENOMEM;
- goto out;
- }
-
- err = xb_read(body, msg->hdr.len);
- if (err) {
- kfree(body);
- kfree(msg);
- goto out;
- }
- body[msg->hdr.len] = '\0';
-
- if (msg->hdr.type == XS_WATCH_EVENT) {
- if (count_strings(body, msg->hdr.len) != 2) {
- err = -EINVAL;
- kfree(msg);
- kfree(body);
- goto out;
- }
- msg->u.watch.path = (const char *)body;
- msg->u.watch.token = (const char *)strchr(body, '\0') + 1;
-
- spin_lock(&watches_lock);
- msg->u.watch.handle = find_watch(msg->u.watch.token);
- if (msg->u.watch.handle != NULL) {
- spin_lock(&watch_events_lock);
- list_add_tail(&msg->list, &watch_events);
- wake_up(&watch_events_waitq);
- spin_unlock(&watch_events_lock);
- } else {
- kfree(body);
- kfree(msg);
- }
- spin_unlock(&watches_lock);
- } else {
- msg->u.reply.body = body;
- spin_lock(&xs_state.reply_lock);
- list_add_tail(&msg->list, &xs_state.reply_list);
- spin_unlock(&xs_state.reply_lock);
- wake_up(&xs_state.reply_waitq);
- }
-
- out:
- mutex_unlock(&xs_state.response_mutex);
- return err;
+ mutex_lock(&xb_write_mutex);
+ list_for_each_entry(req, &xs_reply_list, list)
+ wake_up(&req->wq);
+ list_for_each_entry(req, &xb_write_list, list)
+ wake_up(&req->wq);
+ mutex_unlock(&xb_write_mutex);
+ return NOTIFY_DONE;
}
-static int xenbus_thread(void *unused)
-{
- int err;
-
- for (;;) {
- err = process_msg();
- if (err)
- pr_warn("error %d while reading message\n", err);
- if (kthread_should_stop())
- break;
- }
-
- return 0;
-}
+static struct notifier_block xs_reboot_nb = {
+ .notifier_call = xs_reboot_notify,
+};
int xs_init(void)
{
int err;
struct task_struct *task;
- INIT_LIST_HEAD(&xs_state.reply_list);
- spin_lock_init(&xs_state.reply_lock);
- init_waitqueue_head(&xs_state.reply_waitq);
-
- mutex_init(&xs_state.request_mutex);
- mutex_init(&xs_state.response_mutex);
- mutex_init(&xs_state.transaction_mutex);
- init_rwsem(&xs_state.watch_mutex);
- atomic_set(&xs_state.transaction_count, 0);
- init_waitqueue_head(&xs_state.transaction_wq);
+ register_reboot_notifier(&xs_reboot_nb);
/* Initialize the shared memory rings to talk to xenstored */
err = xb_init_comms();
@@ -977,10 +927,6 @@ int xs_init(void)
return PTR_ERR(task);
xenwatch_pid = task->pid;
- task = kthread_run(xenbus_thread, NULL, "xenbus");
- if (IS_ERR(task))
- return PTR_ERR(task);
-
/* shutdown watches for kexec boot */
xs_reset_watches();