Merge branch 'akpm' (patches from Andrew)

Merge more updates from Andrew Morton:

 - a bit more MM

 - procfs updates

 - dynamic-debug fixes

 - lib/ updates

 - checkpatch

 - epoll

 - nilfs2

 - signals

 - rapidio

 - PID management cleanup and optimization

 - kcov updates

 - sysvipc updates

 - quite a few misc things all over the place

* emailed patches from Andrew Morton <[email protected]>: (94 commits)
  EXPERT Kconfig menu: fix broken EXPERT menu
  include/asm-generic/topology.h: remove unused parent_node() macro
  arch/tile/include/asm/topology.h: remove unused parent_node() macro
  arch/sparc/include/asm/topology_64.h: remove unused parent_node() macro
  arch/sh/include/asm/topology.h: remove unused parent_node() macro
  arch/ia64/include/asm/topology.h: remove unused parent_node() macro
  drivers/pcmcia/sa1111_badge4.c: avoid unused function warning
  mm: add infrastructure for get_user_pages_fast() benchmarking
  sysvipc: make get_maxid O(1) again
  sysvipc: properly name ipc_addid() limit parameter
  sysvipc: duplicate lock comments wrt ipc_addid()
  sysvipc: unteach ids->next_id for !CHECKPOINT_RESTORE
  initramfs: use time64_t timestamps
  drivers/watchdog: make use of devm_register_reboot_notifier()
  kernel/reboot.c: add devm_register_reboot_notifier()
  kcov: update documentation
  Makefile: support flag -fsanitizer-coverage=trace-cmp
  kcov: support comparison operands collection
  kcov: remove pointless current != NULL check
  kernel/panic.c: add TAINT_AUX
  ...

ipc/sem.c

@@ -515,6 +515,7 @@ static int newary(struct ipc_namespace *ns, struct ipc_params *params)
 	sma->sem_nsems = nsems;
 	sma->sem_ctime = ktime_get_real_seconds();
 
+	/* ipc_addid() locks sma upon success. */
 	retval = ipc_addid(&sem_ids(ns), &sma->sem_perm, ns->sc_semmni);
 	if (retval < 0) {
 		call_rcu(&sma->sem_perm.rcu, sem_rcu_free);

ipc/shm.c

@@ -601,6 +601,7 @@ static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
 	shp->shm_file = file;
 	shp->shm_creator = current;
 
+	/* ipc_addid() locks shp upon success. */
 	error = ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni);
 	if (error < 0)
 		goto no_id;

ipc/util.c

@@ -116,13 +116,16 @@ int ipc_init_ids(struct ipc_ids *ids)
 	int err;
 	ids->in_use = 0;
 	ids->seq = 0;
-	ids->next_id = -1;
 	init_rwsem(&ids->rwsem);
 	err = rhashtable_init(&ids->key_ht, &ipc_kht_params);
 	if (err)
 		return err;
 	idr_init(&ids->ipcs_idr);
 	ids->tables_initialized = true;
+	ids->max_id = -1;
+#ifdef CONFIG_CHECKPOINT_RESTORE
+	ids->next_id = -1;
+#endif
 	return 0;
 }
 
@@ -186,41 +189,51 @@ static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key)
 	return NULL;
 }
 
-/**
- * ipc_get_maxid - get the last assigned id
- * @ids: ipc identifier set
- *
- * Called with ipc_ids.rwsem held.
+#ifdef CONFIG_CHECKPOINT_RESTORE
+/*
+ * Specify desired id for next allocated IPC object.
  */
-int ipc_get_maxid(struct ipc_ids *ids)
+#define ipc_idr_alloc(ids, new)						\
+	idr_alloc(&(ids)->ipcs_idr, (new),				\
+		  (ids)->next_id < 0 ? 0 : ipcid_to_idx((ids)->next_id),\
+		  0, GFP_NOWAIT)
+
+static inline int ipc_buildid(int id, struct ipc_ids *ids,
+			      struct kern_ipc_perm *new)
 {
-	struct kern_ipc_perm *ipc;
-	int max_id = -1;
-	int total, id;
-
-	if (ids->in_use == 0)
-		return -1;
-
-	if (ids->in_use == IPCMNI)
-		return IPCMNI - 1;
-
-	/* Look for the last assigned id */
-	total = 0;
-	for (id = 0; id < IPCMNI && total < ids->in_use; id++) {
-		ipc = idr_find(&ids->ipcs_idr, id);
-		if (ipc != NULL) {
-			max_id = id;
-			total++;
-		}
+	if (ids->next_id < 0) { /* default, behave as !CHECKPOINT_RESTORE */
+		new->seq = ids->seq++;
+		if (ids->seq > IPCID_SEQ_MAX)
+			ids->seq = 0;
+	} else {
+		new->seq = ipcid_to_seqx(ids->next_id);
+		ids->next_id = -1;
 	}
-	return max_id;
+
+	return SEQ_MULTIPLIER * new->seq + id;
 }
 
+#else
+#define ipc_idr_alloc(ids, new)					\
+	idr_alloc(&(ids)->ipcs_idr, (new), 0, 0, GFP_NOWAIT)
+
+static inline int ipc_buildid(int id, struct ipc_ids *ids,
+			      struct kern_ipc_perm *new)
+{
+	new->seq = ids->seq++;
+	if (ids->seq > IPCID_SEQ_MAX)
+		ids->seq = 0;
+
+	return SEQ_MULTIPLIER * new->seq + id;
+}
+
+#endif /* CONFIG_CHECKPOINT_RESTORE */
+
 /**
  * ipc_addid - add an ipc identifier
  * @ids: ipc identifier set
  * @new: new ipc permission set
- * @size: limit for the number of used ids
+ * @limit: limit for the number of used ids
  *
  * Add an entry 'new' to the ipc ids idr. The permissions object is
  * initialised and the first free entry is set up and the id assigned
@@ -229,17 +242,16 @@ int ipc_get_maxid(struct ipc_ids *ids)
  *
  * Called with writer ipc_ids.rwsem held.
  */
-int ipc_addid(struct ipc_ids *ids, struct kern_ipc_perm *new, int size)
+int ipc_addid(struct ipc_ids *ids, struct kern_ipc_perm *new, int limit)
 {
 	kuid_t euid;
 	kgid_t egid;
 	int id, err;
-	int next_id = ids->next_id;
 
-	if (size > IPCMNI)
-		size = IPCMNI;
+	if (limit > IPCMNI)
+		limit = IPCMNI;
 
-	if (!ids->tables_initialized || ids->in_use >= size)
+	if (!ids->tables_initialized || ids->in_use >= limit)
 		return -ENOSPC;
 
 	idr_preload(GFP_KERNEL);
@@ -254,9 +266,7 @@ int ipc_addid(struct ipc_ids *ids, struct kern_ipc_perm *new, int size)
 	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);
+	id = ipc_idr_alloc(ids, new);
 	idr_preload_end();
 
 	if (id >= 0 && new->key != IPC_PRIVATE) {
@@ -274,17 +284,11 @@ int ipc_addid(struct ipc_ids *ids, struct kern_ipc_perm *new, int size)
 	}
 
 	ids->in_use++;
+	if (id > ids->max_id)
+		ids->max_id = id;
 
-	if (next_id < 0) {
-		new->seq = ids->seq++;
-		if (ids->seq > IPCID_SEQ_MAX)
-			ids->seq = 0;
-	} else {
-		new->seq = ipcid_to_seqx(next_id);
-		ids->next_id = -1;
-	}
+	new->id = ipc_buildid(id, ids, new);
 
-	new->id = ipc_buildid(id, new->seq);
 	return id;
 }
 
@@ -429,6 +433,15 @@ void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
 	ipc_kht_remove(ids, ipcp);
 	ids->in_use--;
 	ipcp->deleted = true;
+
+	if (unlikely(lid == ids->max_id)) {
+		do {
+			lid--;
+			if (lid == -1)
+				break;
+		} while (!idr_find(&ids->ipcs_idr, lid));
+		ids->max_id = lid;
+	}
 }
 
 /**

ipc/util.h

@@ -13,6 +13,7 @@
 
 #include <linux/unistd.h>
 #include <linux/err.h>
+#include <linux/ipc_namespace.h>
 
 #define SEQ_MULTIPLIER	(IPCMNI)
 
@@ -99,9 +100,6 @@ void __init ipc_init_proc_interface(const char *path, const char *header,
 /* must be called with ids->rwsem acquired for writing */
 int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int);
 
-/* must be called with ids->rwsem acquired for reading */
-int ipc_get_maxid(struct ipc_ids *);
-
 /* must be called with both locks acquired. */
 void ipc_rmid(struct ipc_ids *, struct kern_ipc_perm *);
 
@@ -111,6 +109,23 @@ void ipc_set_key_private(struct ipc_ids *, struct kern_ipc_perm *);
 /* must be called with ipcp locked */
 int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flg);
 
+/**
+ * ipc_get_maxid - get the last assigned id
+ * @ids: ipc identifier set
+ *
+ * Called with ipc_ids.rwsem held for reading.
+ */
+static inline int ipc_get_maxid(struct ipc_ids *ids)
+{
+	if (ids->in_use == 0)
+		return -1;
+
+	if (ids->in_use == IPCMNI)
+		return IPCMNI - 1;
+
+	return ids->max_id;
+}
+
 /*
  * For allocation that need to be freed by RCU.
  * Objects are reference counted, they start with reference count 1.
@@ -146,11 +161,6 @@ extern struct msg_msg *load_msg(const void __user *src, size_t len);
 extern struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst);
 extern int store_msg(void __user *dest, struct msg_msg *msg, size_t len);
 
-static inline int ipc_buildid(int id, int seq)
-{
-	return SEQ_MULTIPLIER * seq + id;
-}
-
 static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int uid)
 {
 	return uid / SEQ_MULTIPLIER != ipcp->seq;