drivers: power: report battery voltage in AOSP compatible format

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

diff --git a/ipc/util.c b/ipc/util.c
index 9a1d779a20e2d98439e0c9954c3d4494849bba18..735342570a875fea7eb77029c1db2fcbc797d422 100644 (file)
--- a/ipc/util.c
+++ b/ipc/util.c
@@ -15,6 +15,29 @@
  * Jun 2006 - namespaces ssupport
  *            OpenVZ, SWsoft Inc.
  *            Pavel Emelianov <xemul@openvz.org>
+ *
+ * General sysv ipc locking scheme:
+ *     rcu_read_lock()
+ *          obtain the ipc object (kern_ipc_perm) by looking up the id in an idr
+ *         tree.
+ *         - perform initial checks (capabilities, auditing and permission,
+ *           etc).
+ *         - perform read-only operations, such as STAT, INFO commands.
+ *           acquire the ipc lock (kern_ipc_perm.lock) through
+ *           ipc_lock_object()
+ *             - perform data updates, such as SET, RMID commands and
+ *               mechanism-specific operations (semop/semtimedop,
+ *               msgsnd/msgrcv, shmat/shmdt).
+ *         drop the ipc lock, through ipc_unlock_object().
+ *     rcu_read_unlock()
+ *
+ *  The ids->rwsem must be taken when:
+ *     - creating, removing and iterating the existing entries in ipc
+ *       identifier sets.
+ *     - iterating through files under /proc/sysvipc/
+ *
+ *  Note that sems have a special fast path that avoids kern_ipc_perm.lock -
+ *  see sem_lock().
  */
 
 #include <linux/mm.h>
@@ -197,7 +220,8 @@ static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key)
                        continue;
                }
 
-               ipc_lock_by_ptr(ipc);
+               rcu_read_lock();
+               ipc_lock_object(ipc);
                return ipc;
        }
 
@@ -268,6 +292,10 @@ int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size)
        rcu_read_lock();
        spin_lock(&new->lock);
 
+       current_euid_egid(&euid, &egid);
+       new->cuid = new->uid = euid;
+       new->gid = new->cgid = egid;
+
        id = idr_alloc(&ids->ipcs_idr, new,
                       (next_id < 0) ? 0 : ipcid_to_idx(next_id), 0,
                       GFP_NOWAIT);
@@ -280,10 +308,6 @@ int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size)
 
        ids->in_use++;
 
-       current_euid_egid(&euid, &egid);
-       new->cuid = new->uid = euid;
-       new->gid = new->cgid = egid;
-
        if (next_id < 0) {
                new->seq = ids->seq++;
                if (ids->seq > ids->seq_max)
@@ -465,11 +489,6 @@ void ipc_free(void* ptr, int size)
                kfree(ptr);
 }
 
-struct ipc_rcu {
-       struct rcu_head rcu;
-       atomic_t refcount;
-} ____cacheline_aligned_in_smp;
-
 /**
  *     ipc_rcu_alloc   -       allocate ipc and rcu space 
  *     @size: size desired
@@ -496,27 +515,24 @@ int ipc_rcu_getref(void *ptr)
        return atomic_inc_not_zero(&p->refcount);
 }
 
-/**
- * ipc_schedule_free - free ipc + rcu space
- * @head: RCU callback structure for queued work
- */
-static void ipc_schedule_free(struct rcu_head *head)
-{
-       vfree(container_of(head, struct ipc_rcu, rcu));
-}
-
-void ipc_rcu_putref(void *ptr)
+void ipc_rcu_putref(void *ptr, void (*func)(struct rcu_head *head))
 {
        struct ipc_rcu *p = ((struct ipc_rcu *)ptr) - 1;
 
        if (!atomic_dec_and_test(&p->refcount))
                return;
 
-       if (is_vmalloc_addr(ptr)) {
-               call_rcu(&p->rcu, ipc_schedule_free);
-       } else {
-               kfree_rcu(p, rcu);
-       }
+       call_rcu(&p->rcu, func);
+}
+
+void ipc_rcu_free(struct rcu_head *head)
+{
+       struct ipc_rcu *p = container_of(head, struct ipc_rcu, rcu);
+
+       if (is_vmalloc_addr(p))
+               vfree(p);
+       else
+               kfree(p);
 }
 
 /**
@@ -677,22 +693,6 @@ out:
        return out;
 }
 
-struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids, int id)
-{
-       struct kern_ipc_perm *out;
-
-       out = ipc_lock(ids, id);
-       if (IS_ERR(out))
-               return out;
-
-       if (ipc_checkid(out, id)) {
-               ipc_unlock(out);
-               return ERR_PTR(-EIDRM);
-       }
-
-       return out;
-}
-
 /**
  * ipcget - Common sys_*get() code
  * @ns : namsepace
@@ -830,7 +830,8 @@ static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos,
                ipc = idr_find(&ids->ipcs_idr, pos);
                if (ipc != NULL) {
                        *new_pos = pos + 1;
-                       ipc_lock_by_ptr(ipc);
+                       rcu_read_lock();
+                       ipc_lock_object(ipc);
                        return ipc;
                }
        }