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 <akpm@linux-foundation.org>: (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
  ...

4 files changed, 75 insertions, 50 deletions

diff --git a/ipc/sem.c b/ipc/sem.c
index a5cff0e109ab..87bd38f38dc3 100644
--- a/ipc/sem.c
+++ b/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);
diff --git a/ipc/shm.c b/ipc/shm.c
index 7733d768666d..7acda23430aa 100644
--- a/ipc/shm.c
+++ b/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;
diff --git a/ipc/util.c b/ipc/util.c
index 79b30eee32cd..ff045fec8d83 100644
--- a/ipc/util.c
+++ b/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->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;
+        }
 
-        if (ids->in_use == 0)
-                return -1;
+        return SEQ_MULTIPLIER * new->seq + id;
+}
 
-        if (ids->in_use == IPCMNI)
-                return IPCMNI - 1;
+#else
+#define ipc_idr_alloc(ids, new)                                 \
+        idr_alloc(&(ids)->ipcs_idr, (new), 0, 0, GFP_NOWAIT)
 
-        /* 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++;
-                }
-        }
-        return max_id;
+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;
+        }
 }
 
 /**
diff --git a/ipc/util.h b/ipc/util.h
index 579112d90016..89b8ec176fc4 100644
--- a/ipc/util.h
+++ b/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;