[Xen-changelog] Add locking for gnttab_free_callback_list.

[Xen patchbot -unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User cl349@xxxxxxxxxxxxxxxxxxxx
# Node ID af9e3ae3a9b1e342514305399fe5dcdfa5639385
# Parent  d13f5c7daddfe41bcb8565d707eb76270a8a6671
Add locking for gnttab_free_callback_list.
Signed-off-by: Christian Limpach <Christian.Limpach@xxxxxxxxxxxx>

diff -r d13f5c7daddf -r af9e3ae3a9b1 
linux-2.6-xen-sparse/arch/xen/kernel/gnttab.c
--- a/linux-2.6-xen-sparse/arch/xen/kernel/gnttab.c     Tue Aug 23 08:41:18 2005
+++ b/linux-2.6-xen-sparse/arch/xen/kernel/gnttab.c     Tue Aug 23 08:45:13 2005
@@ -51,6 +51,7 @@
 static grant_entry_t *shared;
 
 static struct gnttab_free_callback *gnttab_free_callback_list = NULL;
+static spinlock_t gnttab_free_callback_list_lock = SPIN_LOCK_UNLOCKED;
 
 /*
  * Lock-free grant-entry allocator
@@ -69,8 +70,11 @@
 
 static void do_free_callbacks(void)
 {
-    struct gnttab_free_callback *callback = gnttab_free_callback_list, *next;
+    struct gnttab_free_callback *callback, *next;
+    spin_lock_irq(&gnttab_free_callback_list_lock);
+    callback = gnttab_free_callback_list;
     gnttab_free_callback_list = NULL;
+    spin_unlock_irq(&gnttab_free_callback_list_lock);
     while (callback) {
        next = callback->next;
        callback->next = NULL;
@@ -86,8 +90,10 @@
     grant_ref_t fh, nfh = gnttab_free_head;
     do { gnttab_free_list[ref] = fh = nfh; wmb(); }
     while ( unlikely((nfh = cmpxchg(&gnttab_free_head, fh, ref)) != fh) );
+    spin_lock_irq(&gnttab_free_callback_list_lock);
     if ( unlikely(gnttab_free_callback_list) )
        do_free_callbacks();
+    spin_unlock_irq(&gnttab_free_callback_list_lock);
 }
 
 /*
@@ -274,8 +280,10 @@
        return;
     callback->fn = fn;
     callback->arg = arg;
+    spin_lock_irq(&gnttab_free_callback_list_lock);
     callback->next = gnttab_free_callback_list;
     gnttab_free_callback_list = callback;
+    spin_unlock_irq(&gnttab_free_callback_list_lock);
 }
 
 /*

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