The mempolicy mode constants, MPOL_DEFAULT, MPOL_PREFERRED, MPOL_BIND,
and MPOL_INTERLEAVE, are better declared as part of an enum for type
checking.

The policy member of struct mempolicy is also converted from type short
to type unsigned short.  A negative policy does not have any legitimate
meaning, so it is possible to change its type in preparation for adding
optional mode flags later.

The equivalent member of struct shmem_sb_info is also changed from int
to unsigned short.

For compatibility, the policy formal to get_mempolicy() remains as a
pointer to an int:

        int get_mempolicy(int *policy, unsigned long *nmask,
                          unsigned long maxnode, unsigned long addr,
                          unsigned long flags);

although the only possible values is the range of type unsigned short.

Cc: Paul Jackson <[EMAIL PROTECTED]>
Cc: Christoph Lameter <[EMAIL PROTECTED]>
Cc: Lee Schermerhorn <[EMAIL PROTECTED]>
Cc: Andi Kleen <[EMAIL PROTECTED]>
Signed-off-by: David Rientjes <[EMAIL PROTECTED]>
---
 Applies on top of V3 of Lee Schermerhorn's mempolicy patch posted to
 LKML on February 8.

 include/linux/mempolicy.h |   21 +++++++++++----------
 include/linux/shmem_fs.h  |    2 +-
 mm/mempolicy.c            |   29 +++++++++++++++++------------
 mm/shmem.c                |   11 ++++++-----
 4 files changed, 35 insertions(+), 28 deletions(-)

diff --git a/include/linux/mempolicy.h b/include/linux/mempolicy.h
--- a/include/linux/mempolicy.h
+++ b/include/linux/mempolicy.h
@@ -9,12 +9,13 @@
  */
 
 /* Policies */
-#define MPOL_DEFAULT   0
-#define MPOL_PREFERRED 1
-#define MPOL_BIND      2
-#define MPOL_INTERLEAVE        3
-
-#define MPOL_MAX MPOL_INTERLEAVE
+enum mempolicy_mode {
+       MPOL_DEFAULT,
+       MPOL_PREFERRED,
+       MPOL_BIND,
+       MPOL_INTERLEAVE,
+       MPOL_MAX,       /* always last member of mempolicy_mode */
+};
 
 /* Flags for get_mem_policy */
 #define MPOL_F_NODE    (1<<0)  /* return next IL mode instead of node mask */
@@ -62,7 +63,7 @@ struct mm_struct;
  */
 struct mempolicy {
        atomic_t refcnt;
-       short policy;   /* See MPOL_* above */
+       unsigned short policy;  /* See MPOL_* above */
        union {
                struct zonelist  *zonelist;     /* bind */
                short            preferred_node; /* preferred */
@@ -133,8 +134,8 @@ struct shared_policy {
        spinlock_t lock;
 };
 
-void mpol_shared_policy_init(struct shared_policy *info, int policy,
-                               nodemask_t *nodes);
+void mpol_shared_policy_init(struct shared_policy *info,
+               enum mempolicy_mode policy, nodemask_t *nodes);
 int mpol_set_shared_policy(struct shared_policy *info,
                                struct vm_area_struct *vma,
                                struct mempolicy *new);
@@ -200,7 +201,7 @@ static inline int mpol_set_shared_policy(struct 
shared_policy *info,
 }
 
 static inline void mpol_shared_policy_init(struct shared_policy *info,
-                                       int policy, nodemask_t *nodes)
+                       enum mempolicy_type policy, nodemask_t *nodes)
 {
 }
 
diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h
--- a/include/linux/shmem_fs.h
+++ b/include/linux/shmem_fs.h
@@ -34,7 +34,7 @@ struct shmem_sb_info {
        uid_t uid;                  /* Mount uid for root directory */
        gid_t gid;                  /* Mount gid for root directory */
        mode_t mode;                /* Mount mode for root directory */
-       int policy;                 /* Default NUMA memory alloc policy */
+       unsigned short policy;      /* Default NUMA memory alloc policy */
        nodemask_t policy_nodes;    /* nodemask for preferred and bind */
 };
 
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -114,7 +114,7 @@ static void mpol_rebind_policy(struct mempolicy *pol,
                                const nodemask_t *newmask);
 
 /* Do sanity checking on a policy */
-static int mpol_check_policy(int mode, nodemask_t *nodes)
+static int mpol_check_policy(enum mempolicy_mode mode, nodemask_t *nodes)
 {
        int was_empty, is_empty;
 
@@ -159,6 +159,8 @@ static int mpol_check_policy(int mode, nodemask_t *nodes)
                if (!was_empty && is_empty)
                        return -EINVAL;
                break;
+       default:
+               BUG();
        }
        return 0;
 }
@@ -201,7 +203,7 @@ static struct zonelist *bind_zonelist(nodemask_t *nodes)
 }
 
 /* Create a new policy */
-static struct mempolicy *mpol_new(int mode, nodemask_t *nodes)
+static struct mempolicy *mpol_new(enum mempolicy_mode mode, nodemask_t *nodes)
 {
        struct mempolicy *policy;
 
@@ -235,6 +237,8 @@ static struct mempolicy *mpol_new(int mode, nodemask_t 
*nodes)
                        return error_code;
                }
                break;
+       default:
+               BUG();
        }
        policy->policy = mode;
        policy->cpuset_mems_allowed = cpuset_mems_allowed(current);
@@ -479,7 +483,7 @@ static void mpol_set_task_struct_flag(void)
 }
 
 /* Set the process memory policy */
-static long do_set_mempolicy(int mode, nodemask_t *nodes)
+static long do_set_mempolicy(enum mempolicy_mode mode, nodemask_t *nodes)
 {
        struct mempolicy *new;
 
@@ -781,7 +785,7 @@ static struct page *new_vma_page(struct page *page, 
unsigned long private, int *
 #endif
 
 static long do_mbind(unsigned long start, unsigned long len,
-                    unsigned long mode, nodemask_t *nmask,
+                    enum mempolicy_mode mode, nodemask_t *nmask,
                     unsigned long flags)
 {
        struct vm_area_struct *vma;
@@ -791,9 +795,8 @@ static long do_mbind(unsigned long start, unsigned long len,
        int err;
        LIST_HEAD(pagelist);
 
-       if ((flags & ~(unsigned long)(MPOL_MF_STRICT |
+       if (flags & ~(unsigned long)(MPOL_MF_STRICT |
                                      MPOL_MF_MOVE | MPOL_MF_MOVE_ALL))
-           || mode > MPOL_MAX)
                return -EINVAL;
        if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_NICE))
                return -EPERM;
@@ -826,7 +829,7 @@ static long do_mbind(unsigned long start, unsigned long len,
        if (!new)
                flags |= MPOL_MF_DISCONTIG_OK;
 
-       pr_debug("mbind %lx-%lx mode:%ld nodes:%lx\n",start,start+len,
+       pr_debug("mbind %lx-%lx mode:%d nodes:%lx\n",start,start+len,
                 mode, nmask ? nodes_addr(*nmask)[0] : -1);
 
        down_write(&mm->mmap_sem);
@@ -927,6 +930,8 @@ asmlinkage long sys_mbind(unsigned long start, unsigned 
long len,
        nodemask_t nodes;
        int err;
 
+       if (mode >= MPOL_MAX)
+               return -EINVAL;
        err = get_nodes(&nodes, nmask, maxnode);
        if (err)
                return err;
@@ -940,7 +945,7 @@ asmlinkage long sys_set_mempolicy(int mode, unsigned long 
__user *nmask,
        int err;
        nodemask_t nodes;
 
-       if (mode < 0 || mode > MPOL_MAX)
+       if (mode < 0 || mode >= MPOL_MAX)
                return -EINVAL;
        err = get_nodes(&nodes, nmask, maxnode);
        if (err)
@@ -1206,7 +1211,7 @@ static unsigned interleave_nodes(struct mempolicy *policy)
  */
 unsigned slab_node(struct mempolicy *policy)
 {
-       int pol = policy ? policy->policy : MPOL_DEFAULT;
+       enum mempolicy_mode pol = policy ? policy->policy : MPOL_DEFAULT;
 
        switch (pol) {
        case MPOL_INTERLEAVE:
@@ -1634,8 +1639,8 @@ restart:
        return 0;
 }
 
-void mpol_shared_policy_init(struct shared_policy *info, int policy,
-                               nodemask_t *policy_nodes)
+void mpol_shared_policy_init(struct shared_policy *info,
+               enum mempolicy_mode policy, nodemask_t *policy_nodes)
 {
        info->root = RB_ROOT;
        spin_lock_init(&info->lock);
@@ -1853,7 +1858,7 @@ static inline int mpol_to_str(char *buffer, int maxlen, 
struct mempolicy *pol)
        char *p = buffer;
        int l;
        nodemask_t nodes;
-       int mode = pol ? pol->policy : MPOL_DEFAULT;
+       enum mempolicy_mode mode = pol ? pol->policy : MPOL_DEFAULT;
 
        switch (mode) {
        case MPOL_DEFAULT:
diff --git a/mm/shmem.c b/mm/shmem.c
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1082,7 +1082,8 @@ redirty:
 
 #ifdef CONFIG_NUMA
 #ifdef CONFIG_TMPFS
-static int shmem_parse_mpol(char *value, int *policy, nodemask_t *policy_nodes)
+static int shmem_parse_mpol(char *value, unsigned short *policy,
+                           nodemask_t *policy_nodes)
 {
        char *nodelist = strchr(value, ':');
        int err = 1;
@@ -1131,7 +1132,7 @@ out:
        return err;
 }
 
-static void shmem_show_mpol(struct seq_file *seq, int policy,
+static void shmem_show_mpol(struct seq_file *seq, enum mempolicy_mode policy,
                            const nodemask_t policy_nodes)
 {
        char *policy_string;
@@ -1200,14 +1201,14 @@ static struct page *shmem_alloc_page(gfp_t gfp,
 }
 #else /* !CONFIG_NUMA */
 #ifdef CONFIG_TMPFS
-static inline int shmem_parse_mpol(char *value, int *policy,
+static inline int shmem_parse_mpol(char *value, unsigned short *policy,
                                                nodemask_t *policy_nodes)
 {
        return 1;
 }
 
-static inline void shmem_show_mpol(struct seq_file *seq, int policy,
-                           const nodemask_t policy_nodes)
+static inline void shmem_show_mpol(struct seq_file *seq,
+               enum mempolicy_mode policy, const nodemask_t policy_nodes)
 {
 }
 #endif /* CONFIG_TMPFS */
--
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