ipc: clean up ipc/shm.c

Use the macro shm_ids().

Remove useless check for a userspace pointer, because copy_to_user()
will check it.

Some style cleanups.
Signed-off-by: WANG Cong <wangcong@zeuux.org>
Cc: Nadia Derbey <Nadia.Derbey@bull.net>
Cc: Pierre Peiffer <peifferp@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

ipc/shm.c

@@ -75,7 +75,7 @@ void shm_init_ns(struct ipc_namespace *ns)
 	ns->shm_ctlall = SHMALL;
 	ns->shm_ctlmni = SHMMNI;
 	ns->shm_tot = 0;
-	ipc_init_ids(&ns->ids[IPC_SHM_IDS]);
+	ipc_init_ids(&shm_ids(ns));
 }
 
 /*
@@ -644,7 +644,7 @@ asmlinkage long sys_shmctl(int shmid, int cmd, struct shmid_ds __user *buf)
 		if (err)
 			return err;
 
-		memset(&shminfo,0,sizeof(shminfo));
+		memset(&shminfo, 0, sizeof(shminfo));
 		shminfo.shmmni = shminfo.shmseg = ns->shm_ctlmni;
 		shminfo.shmmax = ns->shm_ctlmax;
 		shminfo.shmall = ns->shm_ctlall;
@@ -669,7 +669,7 @@ asmlinkage long sys_shmctl(int shmid, int cmd, struct shmid_ds __user *buf)
 		if (err)
 			return err;
 
-		memset(&shm_info,0,sizeof(shm_info));
+		memset(&shm_info, 0, sizeof(shm_info));
 		down_read(&shm_ids(ns).rw_mutex);
 		shm_info.used_ids = shm_ids(ns).in_use;
 		shm_get_stat (ns, &shm_info.shm_rss, &shm_info.shm_swp);
@@ -678,7 +678,7 @@ asmlinkage long sys_shmctl(int shmid, int cmd, struct shmid_ds __user *buf)
 		shm_info.swap_successes = 0;
 		err = ipc_get_maxid(&shm_ids(ns));
 		up_read(&shm_ids(ns).rw_mutex);
-		if(copy_to_user (buf, &shm_info, sizeof(shm_info))) {
+		if (copy_to_user(buf, &shm_info, sizeof(shm_info))) {
 			err = -EFAULT;
 			goto out;
 		}
@@ -692,11 +692,6 @@ asmlinkage long sys_shmctl(int shmid, int cmd, struct shmid_ds __user *buf)
 		struct shmid64_ds tbuf;
 		int result;
 
-		if (!buf) {
-			err = -EFAULT;
-			goto out;
-		}
-
 		if (cmd == SHM_STAT) {
 			shp = shm_lock(ns, shmid);
 			if (IS_ERR(shp)) {
@@ -712,7 +707,7 @@ asmlinkage long sys_shmctl(int shmid, int cmd, struct shmid_ds __user *buf)
 			}
 			result = 0;
 		}
-		err=-EACCES;
+		err = -EACCES;
 		if (ipcperms (&shp->shm_perm, S_IRUGO))
 			goto out_unlock;
 		err = security_shm_shmctl(shp, cmd);