Greatly enhance the slab allocator.

[srvx.git] / src / alloc-slab.c

diff --git a/src/alloc-slab.c b/src/alloc-slab.c
index 43c857549c30715732e5ab0b843f3e523c701f7c..ac6731a30c84775db22b6c1e9f702ce78a1cd79d 100644 (file)
--- a/src/alloc-slab.c
+++ b/src/alloc-slab.c
@@ -25,8 +25,12 @@
 # error The slab allocator requires that your system have the mmap() system call.
 #endif
 
+#define SLAB_DEBUG_HEADER 1
+#define SLAB_DEBUG_LOG    2
+#define SLAB_DEBUG_PERMS  4
+
 #if !defined(SLAB_DEBUG)
-# define SLAB_DEBUG 1
+# define SLAB_DEBUG 0
 #endif
 
 #if !defined(SLAB_RESERVE)
@@ -37,7 +41,7 @@
 # define MAX_SLAB_FREE 1024
 #endif
 
-#if SLAB_DEBUG
+#if SLAB_DEBUG & SLAB_DEBUG_HEADER
 
 #define ALLOC_MAGIC 0x1a
 #define FREE_MAGIC  0xcf
@@ -131,6 +135,92 @@ unsigned long slab_alloc_size;
 # define MAP_ANON 0
 #endif
 
+#if SLAB_DEBUG & SLAB_DEBUG_LOG
+
+FILE *slab_log;
+
+struct slab_log_entry
+{
+    struct timeval tv;
+    void *slab;
+    ssize_t size;
+};
+
+static void
+close_slab_log(void)
+{
+    fclose(slab_log);
+}
+
+static void
+slab_log_alloc(void *slab, size_t size)
+{
+    struct slab_log_entry sle;
+
+    gettimeofday(&sle.tv, NULL);
+    sle.slab = slab;
+    sle.size = (ssize_t)size;
+
+    if (!slab_log)
+    {
+        const char *fname;
+        fname = getenv("SLAB_LOG_FILE");
+        if (!fname)
+            fname = "slab.log";
+        slab_log = fopen(fname, "w");
+        atexit(close_slab_log);
+    }
+
+    fwrite(&sle, sizeof(sle), 1, slab_log);
+}
+
+static void
+slab_log_free(void *slab, size_t size)
+{
+    struct slab_log_entry sle;
+
+    gettimeofday(&sle.tv, NULL);
+    sle.slab = slab;
+    sle.size = -(ssize_t)size;
+    fwrite(&sle, sizeof(sle), 1, slab_log);
+}
+
+static void
+slab_log_unmap(void *slab)
+{
+    struct slab_log_entry sle;
+
+    gettimeofday(&sle.tv, NULL);
+    sle.slab = slab;
+    sle.size = 0;
+    fwrite(&sle, sizeof(sle), 1, slab_log);
+}
+
+#else
+# define slab_log_alloc(SLAB, SIZE)
+# define slab_log_free(SLAB, SIZE)
+# define slab_log_unmap(SLAB)
+#endif
+
+#if (SLAB_DEBUG & SLAB_DEBUG_PERMS) && defined(HAVE_MPROTECT)
+
+static void
+slab_protect(struct slab *slab)
+{
+    mprotect(slab, (char*)(slab + 1) - (char*)slab->base, PROT_NONE);
+}
+
+static void
+slab_unprotect(struct slab *slab)
+{
+    mprotect(slab, (char*)(slab + 1) - (char*)slab->base, PROT_READ | PROT_WRITE);
+}
+
+#else
+# define slab_protect(SLAB) (void)(SLAB)
+# define slab_unprotect(SLAB) (void)(SLAB)
+#endif
+
 static size_t
 slab_pagesize(void)
 {
@@ -205,6 +295,7 @@ slab_alloc(struct slabset *sset)
         /* Allocate new slab. */
         if (free_slab_head) {
             slab = free_slab_head;
+            slab_unprotect(slab);
             if (!(free_slab_head = slab->next))
                 free_slab_tail = NULL;
         } else {
@@ -213,6 +304,7 @@ slab_alloc(struct slabset *sset)
             slab->base = item;
             slab_count++;
         }
+        slab_log_alloc(slab, sset->size);
 
         /* Populate free list. */
         step = (sset->size + SLAB_ALIGN - 1) & ~(SLAB_ALIGN - 1);
@@ -293,6 +385,8 @@ slab_unalloc(void *ptr, size_t size)
         assert(!slab->next || slab == slab->next->prev);
         assert(!slab->prev || slab == slab->prev->next);
     } else if (!slab->used) {
+        slab_log_free(slab, size);
+
         /* Unlink slab from its parent. */
         slab->parent->nslabs--;
         if (slab->prev)
@@ -320,8 +414,11 @@ slab_unalloc(void *ptr, size_t size)
             free_slab_tail = tslab;
             if (!free_slab_head)
                 free_slab_head = tslab;
-            else
+            else {
+                slab_unprotect(tslab->prev);
                 tslab->prev->next = tslab;
+                slab_protect(tslab->prev);
+            }
             free_slab_count++;
             slab_count++;
         }
@@ -331,11 +428,14 @@ slab_unalloc(void *ptr, size_t size)
         slab->parent = NULL;
         slab->next = NULL;
         slab->prev = free_slab_tail;
-        free_slab_tail = slab;
-        if (free_slab_head)
+        if (slab->prev) {
+            slab_unprotect(slab->prev);
             slab->prev->next = slab;
-        else
+            slab_protect(slab->prev);
+        } else
             free_slab_head = slab;
+        slab_protect(slab);
+        free_slab_tail = slab;
         free_slab_count++;
 
 #if MAX_SLAB_FREE >= 0
@@ -345,13 +445,17 @@ slab_unalloc(void *ptr, size_t size)
             struct slab *tslab;
 
             tslab = free_slab_tail;
+            slab_unprotect(tslab);
             free_slab_tail = tslab->prev;
-            if (tslab->prev)
+            if (tslab->prev) {
+                slab_unprotect(tslab->prev);
                 tslab->prev->next = NULL;
-            else
+                slab_protect(tslab->prev);
+            } else
                 free_slab_head = NULL;
             free_slab_count--;
             slab_count--;
+            slab_log_unmap(slab);
             munmap(slab->base, slab_pagesize());
         }
 #endif
@@ -375,8 +479,9 @@ slab_malloc(const char *file, unsigned int line, size_t size)
         res = slab_map(slab_round_up(real));
         big_alloc_count++;
         big_alloc_size += size;
+        slab_log_alloc(res, size);
     }
-#if SLAB_DEBUG
+#if SLAB_DEBUG & SLAB_DEBUG_HEADER
     res->file_id = get_file_id(file);
     res->size = size;
     res->line = line;
@@ -400,7 +505,7 @@ slab_realloc(const char *file, unsigned int line, void *ptr, size_t size)
 
     verify(ptr);
     orig = (alloc_header_t*)ptr - 1;
-#if SLAB_DEBUG
+#if SLAB_DEBUG & SLAB_DEBUG_HEADER
     osize = orig->size;
 #else
     osize = *orig;
@@ -435,7 +540,7 @@ slab_free(const char *file, unsigned int line, void *ptr)
         return;
     verify(ptr);
     hdr = (alloc_header_t*)ptr - 1;
-#if SLAB_DEBUG
+#if SLAB_DEBUG & SLAB_DEBUG_HEADER
     hdr->file_id = get_file_id(file);
     hdr->line = line;
     hdr->magic = FREE_MAGIC;
@@ -454,6 +559,7 @@ slab_free(const char *file, unsigned int line, void *ptr)
         munmap(hdr, slab_round_up(real));
         big_alloc_count--;
         big_alloc_size -= user;
+        slab_log_unmap(hdr);
     }
 }
 
@@ -469,7 +575,7 @@ verify(const void *ptr)
         return;
 
     hdr = (alloc_header_t*)ptr - 1;
-#if SLAB_DEBUG
+#if SLAB_DEBUG & SLAB_DEBUG_HEADER
     real = hdr->size + sizeof(*hdr);
     assert(hdr->file_id < file_ids_used);
     assert(hdr->magic == ALLOC_MAGIC);