ipc,sem: fine grained locking for semtimedop

[GitHub/mt8127/android_kernel_alcatel_ttab.git] / ipc / util.c

diff --git a/ipc/util.c b/ipc/util.c
index 3df0af3158a58d0f7431011f151c00eb84723cd6..579201e4bc019027f7a3c94c2536451223ee7cf3 100644 (file)
--- a/ipc/util.c
+++ b/ipc/util.c
@@ -439,9 +439,9 @@ void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
  *     NULL is returned if the allocation fails
  */
  
-void* ipc_alloc(int size)
+void *ipc_alloc(int size)
 {
-       void* out;
+       void *out;
        if(size > PAGE_SIZE)
                out = vmalloc(size);
        else
@@ -478,7 +478,7 @@ void ipc_free(void* ptr, int size)
  */
 struct ipc_rcu_hdr
 {
-       int refcount;
+       atomic_t refcount;
        int is_vmalloc;
        void *data[0];
 };
@@ -516,39 +516,41 @@ static inline int rcu_use_vmalloc(int size)
  *     @size: size desired
  *
  *     Allocate memory for the rcu header structure +  the object.
- *     Returns the pointer to the object.
- *     NULL is returned if the allocation fails. 
+ *     Returns the pointer to the object or NULL upon failure.
  */
- 
-void* ipc_rcu_alloc(int size)
+void *ipc_rcu_alloc(int size)
 {
-       void* out;
-       /* 
+       void *out;
+
+       /*
         * We prepend the allocation with the rcu struct, and
-        * workqueue if necessary (for vmalloc). 
+        * workqueue if necessary (for vmalloc).
         */
        if (rcu_use_vmalloc(size)) {
                out = vmalloc(HDRLEN_VMALLOC + size);
-               if (out) {
-                       out += HDRLEN_VMALLOC;
-                       container_of(out, struct ipc_rcu_hdr, data)->is_vmalloc = 1;
-                       container_of(out, struct ipc_rcu_hdr, data)->refcount = 1;
-               }
+               if (!out)
+                       goto done;
+
+               out += HDRLEN_VMALLOC;
+               container_of(out, struct ipc_rcu_hdr, data)->is_vmalloc = 1;
        } else {
                out = kmalloc(HDRLEN_KMALLOC + size, GFP_KERNEL);
-               if (out) {
-                       out += HDRLEN_KMALLOC;
-                       container_of(out, struct ipc_rcu_hdr, data)->is_vmalloc = 0;
-                       container_of(out, struct ipc_rcu_hdr, data)->refcount = 1;
-               }
+               if (!out)
+                       goto done;
+
+               out += HDRLEN_KMALLOC;
+               container_of(out, struct ipc_rcu_hdr, data)->is_vmalloc = 0;
        }
 
+       /* set reference counter no matter what kind of allocation was done */
+       atomic_set(&container_of(out, struct ipc_rcu_hdr, data)->refcount, 1);
+done:
        return out;
 }
 
-void ipc_rcu_getref(void *ptr)
+int ipc_rcu_getref(void *ptr)
 {
-       container_of(ptr, struct ipc_rcu_hdr, data)->refcount++;
+       return atomic_inc_not_zero(&container_of(ptr, struct ipc_rcu_hdr, data)->refcount);
 }
 
 static void ipc_do_vfree(struct work_struct *work)
@@ -578,7 +580,7 @@ static void ipc_schedule_free(struct rcu_head *head)
 
 void ipc_rcu_putref(void *ptr)
 {
-       if (--container_of(ptr, struct ipc_rcu_hdr, data)->refcount > 0)
+       if (!atomic_dec_and_test(&container_of(ptr, struct ipc_rcu_hdr, data)->refcount))
                return;
 
        if (container_of(ptr, struct ipc_rcu_hdr, data)->is_vmalloc) {