talloc: Decouple the dual use of chunk->pool

If we want nested pools, we will have pools that are pool members. So
we will have to have a separate "next object" pointer  for pools. As
we have struct talloc_pool_chunk now, this additional pointer does not
affect normal talloc objects.

Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Stefan Metzmacher <metze@samba.org>

diff --git a/lib/talloc/talloc.c b/lib/talloc/talloc.c
index 69d5a16c0a1665b71f5f8667815540c579fabf88..74db284aa0d807447255cdf8a2d64394771e7047 100644 (file)
--- a/lib/talloc/talloc.c
+++ b/lib/talloc/talloc.c
@@ -244,6 +244,8 @@ static void talloc_memlimit_update_on_free(struct talloc_chunk *tc);
 
 typedef int (*talloc_destructor_t)(void *);
 
+union talloc_pool_chunk;
+
 struct talloc_chunk {
        struct talloc_chunk *next, *prev;
        struct talloc_chunk *parent, *child;
@@ -263,17 +265,12 @@ struct talloc_chunk {
        struct talloc_memlimit *limit;
 
        /*
-        * "pool" has dual use:
-        *
-        * For the talloc pool itself (i.e. TALLOC_FLAG_POOL is set), "pool"
-        * marks the end of the currently allocated area.
-        *
-        * For members of the pool (i.e. TALLOC_FLAG_POOLMEM is set), "pool"
+        * For members of a pool (i.e. TALLOC_FLAG_POOLMEM is set), "pool"
         * is a pointer to the struct talloc_chunk of the pool that it was
         * allocated from. This way children can quickly find the pool to chew
         * from.
         */
-       void *pool;
+       union talloc_pool_chunk *pool;
 };
 
 /* 16 byte alignment seems to keep everyone happy */
@@ -466,6 +463,7 @@ union talloc_pool_chunk {
         * on 32-bit platforms. */
        struct tc_pool_hdr {
                struct talloc_chunk c;
+               void *next;
                unsigned int object_count;
        } hdr;
        /* This makes it always 16 byte aligned. */
@@ -479,7 +477,7 @@ static void *tc_pool_end(union talloc_pool_chunk *pool_tc)
 
 static size_t tc_pool_space_left(union talloc_pool_chunk *pool_tc)
 {
-       return (char *)tc_pool_end(pool_tc) - (char *)pool_tc->hdr.c.pool;
+       return (char *)tc_pool_end(pool_tc) - (char *)pool_tc->hdr.next;
 }
 
 static void *tc_pool_first_chunk(union talloc_pool_chunk *pool_tc)
@@ -499,11 +497,11 @@ static void tc_invalidate_pool(union talloc_pool_chunk *pool_tc)
        size_t flen = tc_pool_space_left(pool_tc);
 
        if (unlikely(talloc_fill.enabled)) {
-               memset(pool_tc->hdr.c.pool, talloc_fill.fill_value, flen);
+               memset(pool_tc->hdr.next, talloc_fill.fill_value, flen);
        }
 
 #if defined(DEVELOPER) && defined(VALGRIND_MAKE_MEM_NOACCESS)
-       VALGRIND_MAKE_MEM_NOACCESS(pool_tc->hdr.c.pool, flen);
+       VALGRIND_MAKE_MEM_NOACCESS(pool_tc->hdr.next, flen);
 #endif
 }
 
@@ -527,7 +525,7 @@ static struct talloc_chunk *talloc_alloc_pool(struct talloc_chunk *parent,
                pool_ctx = (union talloc_pool_chunk *)parent;
        }
        else if (parent->flags & TALLOC_FLAG_POOLMEM) {
-               pool_ctx = (union talloc_pool_chunk *)parent->pool;
+               pool_ctx = parent->pool;
        }
 
        if (pool_ctx == NULL) {
@@ -545,13 +543,13 @@ static struct talloc_chunk *talloc_alloc_pool(struct talloc_chunk *parent,
                return NULL;
        }
 
-       result = (struct talloc_chunk *)pool_ctx->hdr.c.pool;
+       result = (struct talloc_chunk *)pool_ctx->hdr.next;
 
 #if defined(DEVELOPER) && defined(VALGRIND_MAKE_MEM_UNDEFINED)
        VALGRIND_MAKE_MEM_UNDEFINED(result, size);
 #endif
 
-       pool_ctx->hdr.c.pool = (void *)((char *)result + chunk_size);
+       pool_ctx->hdr.next = (void *)((char *)result + chunk_size);
 
        result->flags = TALLOC_MAGIC | TALLOC_FLAG_POOLMEM;
        result->pool = pool_ctx;
@@ -653,7 +651,7 @@ _PUBLIC_ void *talloc_pool(const void *context, size_t size)
                return NULL;
        }
        pool_tc->hdr.c.flags |= TALLOC_FLAG_POOL;
-       pool_tc->hdr.c.pool = tc_pool_first_chunk(pool_tc);
+       pool_tc->hdr.next = tc_pool_first_chunk(pool_tc);
 
        pool_tc->hdr.object_count = 1;
 
@@ -763,7 +761,7 @@ static inline void _talloc_free_poolmem(struct talloc_chunk *tc,
        union talloc_pool_chunk *pool;
        void *next_tc;
 
-       pool = (union talloc_pool_chunk *)tc->pool;
+       pool = tc->pool;
        next_tc = tc_next_chunk(tc);
 
        tc->flags |= TALLOC_FLAG_FREE;
@@ -792,7 +790,7 @@ static inline void _talloc_free_poolmem(struct talloc_chunk *tc,
                 * the rest is available for new objects
                 * again.
                 */
-               pool->hdr.c.pool = tc_pool_first_chunk(pool);
+               pool->hdr.next = tc_pool_first_chunk(pool);
                tc_invalidate_pool(pool);
                return;
        }
@@ -812,13 +810,13 @@ static inline void _talloc_free_poolmem(struct talloc_chunk *tc,
                return;
        }
 
-       if (pool->hdr.c.pool == next_tc) {
+       if (pool->hdr.next == next_tc) {
                /*
                 * if pool->pool still points to end of
                 * 'tc' (which is stored in the 'next_tc' variable),
                 * we can reclaim the memory of 'tc'.
                 */
-               pool->hdr.c.pool = tc;
+               pool->hdr.next = tc;
                return;
        }
 
@@ -1516,7 +1514,7 @@ _PUBLIC_ void *_talloc_realloc(const void *context, void *ptr, size_t size, cons
 
        /* handle realloc inside a talloc_pool */
        if (unlikely(tc->flags & TALLOC_FLAG_POOLMEM)) {
-               pool_tc = (union talloc_pool_chunk *)tc->pool;
+               pool_tc = tc->pool;
        }
 
 #if (ALWAYS_REALLOC == 0)
@@ -1526,9 +1524,9 @@ _PUBLIC_ void *_talloc_realloc(const void *context, void *ptr, size_t size, cons
                        void *next_tc = tc_next_chunk(tc);
                        TC_INVALIDATE_SHRINK_CHUNK(tc, size);
                        tc->size = size;
-                       if (next_tc == pool_tc->hdr.c.pool) {
+                       if (next_tc == pool_tc->hdr.next) {
                                /* note: tc->size has changed, so this works */
-                               pool_tc->hdr.c.pool = tc_next_chunk(tc);
+                               pool_tc->hdr.next = tc_next_chunk(tc);
                        }
                        return ptr;
                } else if ((tc->size - size) < 1024) {
@@ -1640,11 +1638,11 @@ _PUBLIC_ void *_talloc_realloc(const void *context, void *ptr, size_t size, cons
                                 * because we want to invalidate the padding
                                 * too.
                                 */
-                               pool_tc->hdr.c.pool = new_used + (char *)new_ptr;
+                               pool_tc->hdr.next = new_used + (char *)new_ptr;
                                tc_invalidate_pool(pool_tc);
 
                                /* now the aligned pointer */
-                               pool_tc->hdr.c.pool = new_chunk_size + (char *)new_ptr;
+                               pool_tc->hdr.next = new_chunk_size + (char *)new_ptr;
                                goto got_new_ptr;
                        }
 
@@ -1658,7 +1656,7 @@ _PUBLIC_ void *_talloc_realloc(const void *context, void *ptr, size_t size, cons
                        return ptr;
                }
 
-               if (next_tc == pool_tc->hdr.c.pool) {
+               if (next_tc == pool_tc->hdr.next) {
                        /*
                         * optimize for the case where 'tc' is the last
                         * chunk in the pool.
@@ -1670,7 +1668,7 @@ _PUBLIC_ void *_talloc_realloc(const void *context, void *ptr, size_t size, cons
                                TC_UNDEFINE_GROW_CHUNK(tc, size);
                                tc->flags &= ~TALLOC_FLAG_FREE;
                                tc->size = size;
-                               pool_tc->hdr.c.pool = tc_next_chunk(tc);
+                               pool_tc->hdr.next = tc_next_chunk(tc);
                                return ptr;
                        }
                }