xenbus: Avoid deadlock during suspend due to open transactions

[thirdparty/kernel/stable.git] / drivers / xen / xenbus / xenbus_dev_frontend.c

diff --git a/drivers/xen/xenbus/xenbus_dev_frontend.c b/drivers/xen/xenbus/xenbus_dev_frontend.c
index c3e201025ef015b49703cf311e71f1d1f041ec6e..39c63152a35800665ca5deadb9656b13fe90088c 100644 (file)
--- a/drivers/xen/xenbus/xenbus_dev_frontend.c
+++ b/drivers/xen/xenbus/xenbus_dev_frontend.c
@@ -62,6 +62,8 @@
 
 #include "xenbus.h"
 
+unsigned int xb_dev_generation_id;
+
 /*
  * An element of a list of outstanding transactions, for which we're
  * still waiting a reply.
@@ -69,6 +71,7 @@
 struct xenbus_transaction_holder {
        struct list_head list;
        struct xenbus_transaction handle;
+       unsigned int generation_id;
 };
 
 /*
@@ -441,6 +444,7 @@ static int xenbus_write_transaction(unsigned msg_type,
                        rc = -ENOMEM;
                        goto out;
                }
+               trans->generation_id = xb_dev_generation_id;
                list_add(&trans->list, &u->transactions);
        } else if (msg->hdr.tx_id != 0 &&
                   !xenbus_get_transaction(u, msg->hdr.tx_id))
@@ -449,6 +453,20 @@ static int xenbus_write_transaction(unsigned msg_type,
                 !(msg->hdr.len == 2 &&
                   (!strcmp(msg->body, "T") || !strcmp(msg->body, "F"))))
                return xenbus_command_reply(u, XS_ERROR, "EINVAL");
+       else if (msg_type == XS_TRANSACTION_END) {
+               trans = xenbus_get_transaction(u, msg->hdr.tx_id);
+               if (trans && trans->generation_id != xb_dev_generation_id) {
+                       list_del(&trans->list);
+                       kfree(trans);
+                       if (!strcmp(msg->body, "T"))
+                               return xenbus_command_reply(u, XS_ERROR,
+                                                           "EAGAIN");
+                       else
+                               return xenbus_command_reply(u,
+                                                           XS_TRANSACTION_END,
+                                                           "OK");
+               }
+       }
 
        rc = xenbus_dev_request_and_reply(&msg->hdr, u);
        if (rc && trans) {
@@ -622,9 +640,7 @@ static int xenbus_file_open(struct inode *inode, struct file *filp)
        if (xen_store_evtchn == 0)
                return -ENOENT;
 
-       nonseekable_open(inode, filp);
-
-       filp->f_mode &= ~FMODE_ATOMIC_POS; /* cdev-style semantics */
+       stream_open(inode, filp);
 
        u = kzalloc(sizeof(*u), GFP_KERNEL);
        if (u == NULL)