mempolicy: create mempolicy_operations structure

Create a mempolicy_operations structure that currently points to two
functions[*] for the various modes:

	int (*create)(struct mempolicy *, const nodemask_t *);
	void (*rebind)(struct mempolicy *, const nodemask_t *);

This splits the implementation for the various modes out of two large
functions, mpol_new() and mpol_rebind_policy().  Eventually it may be
beneficial to add additional functions to accomodate the existing switch()
statements in mm/mempolicy.c.

 [*] The ->create() function for MPOL_DEFAULT is currently NULL since no
     struct mempolicy is dynamically allocated.

[Lee.Schermerhorn@hp.com: fix regression in the package mempolicy regression tests]
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Paul Jackson <pj@sgi.com>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Eric Whitney <eric.whitney@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index d44c524..a94d994 100644 (file)
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -63,7 +63,6 @@
    grows down?
    make bind policy root only? It can trigger oom much faster and the
    kernel is not always grateful with that.
-   could replace all the switch()es with a mempolicy_ops structure.
 */
 
 #include <linux/mempolicy.h>
@@ -110,8 +109,13 @@ struct mempolicy default_policy = {
        .policy = MPOL_DEFAULT,
 };
 
+static const struct mempolicy_operations {
+       int (*create)(struct mempolicy *pol, const nodemask_t *nodes);
+       void (*rebind)(struct mempolicy *pol, const nodemask_t *nodes);
+} mpol_ops[MPOL_MAX];
+
 /* Check that the nodemask contains at least one populated zone */
-static int is_valid_nodemask(nodemask_t *nodemask)
+static int is_valid_nodemask(const nodemask_t *nodemask)
 {
        int nd, k;
 
@@ -144,125 +148,151 @@ static void mpol_relative_nodemask(nodemask_t *ret, const nodemask_t *orig,
        nodes_onto(*ret, tmp, *rel);
 }
 
+static int mpol_new_interleave(struct mempolicy *pol, const nodemask_t *nodes)
+{
+       if (nodes_empty(*nodes))
+               return -EINVAL;
+       pol->v.nodes = *nodes;
+       return 0;
+}
+
+static int mpol_new_preferred(struct mempolicy *pol, const nodemask_t *nodes)
+{
+       if (!nodes)
+               pol->v.preferred_node = -1;     /* local allocation */
+       else if (nodes_empty(*nodes))
+               return -EINVAL;                 /*  no allowed nodes */
+       else
+               pol->v.preferred_node = first_node(*nodes);
+       return 0;
+}
+
+static int mpol_new_bind(struct mempolicy *pol, const nodemask_t *nodes)
+{
+       if (!is_valid_nodemask(nodes))
+               return -EINVAL;
+       pol->v.nodes = *nodes;
+       return 0;
+}
+
 /* Create a new policy */
 static struct mempolicy *mpol_new(unsigned short mode, unsigned short flags,
                                  nodemask_t *nodes)
 {
        struct mempolicy *policy;
        nodemask_t cpuset_context_nmask;
+       int localalloc = 0;
+       int ret;
 
        pr_debug("setting mode %d flags %d nodes[0] %lx\n",
                 mode, flags, nodes ? nodes_addr(*nodes)[0] : -1);
 
        if (mode == MPOL_DEFAULT)
-               return (nodes && nodes_weight(*nodes)) ? ERR_PTR(-EINVAL) :
-                                                        NULL;
+               return NULL;
+       if (!nodes || nodes_empty(*nodes)) {
+               if (mode != MPOL_PREFERRED)
+                       return ERR_PTR(-EINVAL);
+               localalloc = 1; /* special case:  no mode flags */
+       }
        policy = kmem_cache_alloc(policy_cache, GFP_KERNEL);
        if (!policy)
                return ERR_PTR(-ENOMEM);
        atomic_set(&policy->refcnt, 1);
-       cpuset_update_task_memory_state();
-       if (flags & MPOL_F_RELATIVE_NODES)
-               mpol_relative_nodemask(&cpuset_context_nmask, nodes,
-                                      &cpuset_current_mems_allowed);
-       else
-               nodes_and(cpuset_context_nmask, *nodes,
-                         cpuset_current_mems_allowed);
-       switch (mode) {
-       case MPOL_INTERLEAVE:
-               if (nodes_empty(*nodes) || nodes_empty(cpuset_context_nmask))
-                       goto free;
-               policy->v.nodes = cpuset_context_nmask;
-               break;
-       case MPOL_PREFERRED:
-               policy->v.preferred_node = first_node(cpuset_context_nmask);
-               if (policy->v.preferred_node >= MAX_NUMNODES)
-                       goto free;
-               break;
-       case MPOL_BIND:
-               if (!is_valid_nodemask(&cpuset_context_nmask))
-                       goto free;
-               policy->v.nodes = cpuset_context_nmask;
-               break;
-       default:
-               BUG();
-       }
        policy->policy = mode;
-       policy->flags = flags;
-       if (mpol_store_user_nodemask(policy))
-               policy->w.user_nodemask = *nodes;
-       else
-               policy->w.cpuset_mems_allowed = cpuset_mems_allowed(current);
+
+       if (!localalloc) {
+               policy->flags = flags;
+               cpuset_update_task_memory_state();
+               if (flags & MPOL_F_RELATIVE_NODES)
+                       mpol_relative_nodemask(&cpuset_context_nmask, nodes,
+                                              &cpuset_current_mems_allowed);
+               else
+                       nodes_and(cpuset_context_nmask, *nodes,
+                                 cpuset_current_mems_allowed);
+               if (mpol_store_user_nodemask(policy))
+                       policy->w.user_nodemask = *nodes;
+               else
+                       policy->w.cpuset_mems_allowed =
+                                               cpuset_mems_allowed(current);
+       }
+
+       ret = mpol_ops[mode].create(policy,
+                               localalloc ? NULL : &cpuset_context_nmask);
+       if (ret < 0) {
+               kmem_cache_free(policy_cache, policy);
+               return ERR_PTR(ret);
+       }
        return policy;
+}
+
+static void mpol_rebind_default(struct mempolicy *pol, const nodemask_t *nodes)
+{
+}
+
+static void mpol_rebind_nodemask(struct mempolicy *pol,
+                                const nodemask_t *nodes)
+{
+       nodemask_t tmp;
+
+       if (pol->flags & MPOL_F_STATIC_NODES)
+               nodes_and(tmp, pol->w.user_nodemask, *nodes);
+       else if (pol->flags & MPOL_F_RELATIVE_NODES)
+               mpol_relative_nodemask(&tmp, &pol->w.user_nodemask, nodes);
+       else {
+               nodes_remap(tmp, pol->v.nodes, pol->w.cpuset_mems_allowed,
+                           *nodes);
+               pol->w.cpuset_mems_allowed = *nodes;
+       }
 
-free:
-       kmem_cache_free(policy_cache, policy);
-       return ERR_PTR(-EINVAL);
+       pol->v.nodes = tmp;
+       if (!node_isset(current->il_next, tmp)) {
+               current->il_next = next_node(current->il_next, tmp);
+               if (current->il_next >= MAX_NUMNODES)
+                       current->il_next = first_node(tmp);
+               if (current->il_next >= MAX_NUMNODES)
+                       current->il_next = numa_node_id();
+       }
+}
+
+static void mpol_rebind_preferred(struct mempolicy *pol,
+                                 const nodemask_t *nodes)
+{
+       nodemask_t tmp;
+
+       /*
+        * check 'STATIC_NODES first, as preferred_node == -1 may be
+        * a temporary, "fallback" state for this policy.
+        */
+       if (pol->flags & MPOL_F_STATIC_NODES) {
+               int node = first_node(pol->w.user_nodemask);
+
+               if (node_isset(node, *nodes))
+                       pol->v.preferred_node = node;
+               else
+                       pol->v.preferred_node = -1;
+       } else if (pol->v.preferred_node == -1) {
+               return; /* no remap required for explicit local alloc */
+       } else if (pol->flags & MPOL_F_RELATIVE_NODES) {
+               mpol_relative_nodemask(&tmp, &pol->w.user_nodemask, nodes);
+               pol->v.preferred_node = first_node(tmp);
+       } else {
+               pol->v.preferred_node = node_remap(pol->v.preferred_node,
+                                                  pol->w.cpuset_mems_allowed,
+                                                  *nodes);
+               pol->w.cpuset_mems_allowed = *nodes;
+       }
 }
 
 /* Migrate a policy to a different set of nodes */
 static void mpol_rebind_policy(struct mempolicy *pol,
                               const nodemask_t *newmask)
 {
-       nodemask_t tmp;
-       int static_nodes;
-       int relative_nodes;
-
        if (!pol)
                return;
-       static_nodes = pol->flags & MPOL_F_STATIC_NODES;
-       relative_nodes = pol->flags & MPOL_F_RELATIVE_NODES;
        if (!mpol_store_user_nodemask(pol) &&
            nodes_equal(pol->w.cpuset_mems_allowed, *newmask))
                return;
-
-       switch (pol->policy) {
-       case MPOL_DEFAULT:
-               break;
-       case MPOL_BIND:
-               /* Fall through */
-       case MPOL_INTERLEAVE:
-               if (static_nodes)
-                       nodes_and(tmp, pol->w.user_nodemask, *newmask);
-               else if (relative_nodes)
-                       mpol_relative_nodemask(&tmp, &pol->w.user_nodemask,
-                                              newmask);
-               else {
-                       nodes_remap(tmp, pol->v.nodes,
-                                   pol->w.cpuset_mems_allowed, *newmask);
-                       pol->w.cpuset_mems_allowed = *newmask;
-               }
-               pol->v.nodes = tmp;
-               if (!node_isset(current->il_next, tmp)) {
-                       current->il_next = next_node(current->il_next, tmp);
-                       if (current->il_next >= MAX_NUMNODES)
-                               current->il_next = first_node(tmp);
-                       if (current->il_next >= MAX_NUMNODES)
-                               current->il_next = numa_node_id();
-               }
-               break;
-       case MPOL_PREFERRED:
-               if (static_nodes) {
-                       int node = first_node(pol->w.user_nodemask);
-
-                       if (node_isset(node, *newmask))
-                               pol->v.preferred_node = node;
-                       else
-                               pol->v.preferred_node = -1;
-               } else if (relative_nodes) {
-                       mpol_relative_nodemask(&tmp, &pol->w.user_nodemask,
-                                              newmask);
-                       pol->v.preferred_node = first_node(tmp);
-               } else {
-                       pol->v.preferred_node = node_remap(pol->v.preferred_node,
-                                       pol->w.cpuset_mems_allowed, *newmask);
-                       pol->w.cpuset_mems_allowed = *newmask;
-               }
-               break;
-       default:
-               BUG();
-               break;
-       }
+       mpol_ops[pol->policy].rebind(pol, newmask);
 }
 
 /*
@@ -291,6 +321,24 @@ void mpol_rebind_mm(struct mm_struct *mm, nodemask_t *new)
        up_write(&mm->mmap_sem);
 }
 
+static const struct mempolicy_operations mpol_ops[MPOL_MAX] = {
+       [MPOL_DEFAULT] = {
+               .rebind = mpol_rebind_default,
+       },
+       [MPOL_INTERLEAVE] = {
+               .create = mpol_new_interleave,
+               .rebind = mpol_rebind_nodemask,
+       },
+       [MPOL_PREFERRED] = {
+               .create = mpol_new_preferred,
+               .rebind = mpol_rebind_preferred,
+       },
+       [MPOL_BIND] = {
+               .create = mpol_new_bind,
+               .rebind = mpol_rebind_nodemask,
+       },
+};
+
 static void gather_stats(struct page *, void *, int pte_dirty);
 static void migrate_page_add(struct page *page, struct list_head *pagelist,
                                unsigned long flags);
@@ -1848,7 +1896,6 @@ void numa_default_policy(void)
 /*
  * Display pages allocated per node and memory policy via /proc.
  */
-
 static const char * const policy_types[] =
        { "default", "prefer", "bind", "interleave" };