X-Git-Url: http://pilppa.org/gitweb/?a=blobdiff_plain;f=ipc%2Futil.h;h=9ffea40457cedb17eca4cc9df13ed1b3a5f1a3f7;hb=73cf60232ef16e1f8a64defa97214a1722db1e6c;hp=99414a36a2504e42d4745b184247537e1777d539;hpb=f4566f04854d78acfc74b9acb029744acde9d033;p=linux-2.6-omap-h63xx.git

diff --git a/ipc/util.h b/ipc/util.h
index 99414a36a25..9ffea40457c 100644
--- a/ipc/util.h
+++ b/ipc/util.h
@@ -32,7 +32,7 @@ struct ipc_ids {
 	int in_use;
 	unsigned short seq;
 	unsigned short seq_max;
-	struct mutex mutex;
+	struct rw_semaphore rw_mutex;
 	struct idr ipcs_idr;
 };
 
@@ -81,8 +81,10 @@ void __init ipc_init_proc_interface(const char *path, const char *header,
 
 #define ipcid_to_idx(id) ((id) % SEQ_MULTIPLIER)
 
-/* must be called with ids->mutex acquired.*/
+/* must be called with ids->rw_mutex acquired for writing */
 int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int);
+
+/* must be called with ids->rw_mutex acquired for reading */
 int ipc_get_maxid(struct ipc_ids *);
 
 /* must be called with both locks acquired. */
@@ -107,6 +109,11 @@ void* ipc_rcu_alloc(int size);
 void ipc_rcu_getref(void *ptr);
 void ipc_rcu_putref(void *ptr);
 
+/*
+ * ipc_lock_down: called with rw_mutex held
+ * ipc_lock: called without that lock held
+ */
+struct kern_ipc_perm *ipc_lock_down(struct ipc_ids *, int);
 struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int);
 
 void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out);
@@ -127,7 +134,7 @@ extern int ipcget_new(struct ipc_namespace *, struct ipc_ids *,
 extern int ipcget_public(struct ipc_namespace *, struct ipc_ids *,
 			struct ipc_ops *, struct ipc_params *);
 
-static inline int ipc_buildid(struct ipc_ids *ids, int id, int seq)
+static inline int ipc_buildid(int id, int seq)
 {
 	return SEQ_MULTIPLIER * seq + id;
 }
@@ -135,8 +142,7 @@ static inline int ipc_buildid(struct ipc_ids *ids, int id, int seq)
 /*
  * Must be called with ipcp locked
  */
-static inline int ipc_checkid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp,
-				int uid)
+static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int uid)
 {
 	if (uid / SEQ_MULTIPLIER != ipcp->seq)
 		return 1;
@@ -155,6 +161,23 @@ static inline void ipc_unlock(struct kern_ipc_perm *perm)
 	rcu_read_unlock();
 }
 
+static inline struct kern_ipc_perm *ipc_lock_check_down(struct ipc_ids *ids,
+						int id)
+{
+	struct kern_ipc_perm *out;
+
+	out = ipc_lock_down(ids, id);
+	if (IS_ERR(out))
+		return out;
+
+	if (ipc_checkid(out, id)) {
+		ipc_unlock(out);
+		return ERR_PTR(-EIDRM);
+	}
+
+	return out;
+}
+
 static inline struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids,
 						int id)
 {
@@ -164,7 +187,7 @@ static inline struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids,
 	if (IS_ERR(out))
 		return out;
 
-	if (ipc_checkid(ids, out, id)) {
+	if (ipc_checkid(out, id)) {
 		ipc_unlock(out);
 		return ERR_PTR(-EIDRM);
 	}