From: Willy Tarreau <w@1wt.eu>
Date: Wed, 23 Feb 2022 09:20:37 +0000 (+0100)
Subject: MINOR: pools: replace DEBUG_MEMORY_POOLS with runtime POOL_DBG_TAG
X-Git-Tag: v2.6-dev2~74
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=13d7775b068241d4d2aa79ac8c987894fada05e9;p=thirdparty%2Fhaproxy.git

MINOR: pools: replace DEBUG_MEMORY_POOLS with runtime POOL_DBG_TAG

This option used to allow to store a marker at the end of the area, which
was used as a canary and detection against wrong freeing while the object
is used, and as a pointer to the last pool_free() caller when back in cache.
Now that we can compute the offsets at runtime, let's check it at run time
and continue the code simplification.
---

diff --git a/include/haproxy/pool-t.h b/include/haproxy/pool-t.h
index b68a4ab4d3..6f77bd9857 100644
--- a/include/haproxy/pool-t.h
+++ b/include/haproxy/pool-t.h
@@ -48,6 +48,7 @@
 #define POOL_DBG_NO_GLOBAL  0x00000010  // disable global pools
 #define POOL_DBG_NO_CACHE   0x00000020  // disable thread-local pool caches
 #define POOL_DBG_CALLER     0x00000040  // trace last caller's location
+#define POOL_DBG_TAG        0x00000080  // place a tag at the end of the area
 
 
 /* This is the head of a thread-local cache */
diff --git a/include/haproxy/pool.h b/include/haproxy/pool.h
index b1a0c60dd0..2f5d7b1d3d 100644
--- a/include/haproxy/pool.h
+++ b/include/haproxy/pool.h
@@ -52,13 +52,13 @@
  * this location is used to keep a pointer to the pool the object was
  * allocated from, and verify it's freed into the appropriate one.
  */
-#ifdef DEBUG_MEMORY_POOLS
-
 # define POOL_EXTRA_MARK (sizeof(void *))
 # define POOL_DEBUG_SET_MARK(pool, item)				\
 	do {								\
 		typeof(pool) __p = (pool);				\
 		typeof(item) __i = (item);				\
+		if (likely(!(pool_debugging & POOL_DBG_TAG)))		\
+			break;						\
 		*(typeof(pool)*)(((char *)__i) + __p->size) = __p;	\
 	} while (0)
 
@@ -66,6 +66,8 @@
 	do {								\
 		typeof(pool) __p = (pool);				\
 		typeof(item) __i = (item);				\
+		if (likely(!(pool_debugging & POOL_DBG_TAG)))		\
+			break;						\
 		*(typeof(pool)*)(((char *)__i) + __p->size) = __builtin_return_address(0); \
 	} while (0)
 
@@ -73,19 +75,12 @@
 	do {								\
 		typeof(pool) __p = (pool);				\
 		typeof(item) __i = (item);				\
+		if (likely(!(pool_debugging & POOL_DBG_TAG)))		\
+			break;						\
 		if (*(typeof(pool)*)(((char *)__i) + __p->size) != __p)	\
 			ABORT_NOW();					\
 	} while (0)
 
-#else // DEBUG_MEMORY_POOLS
-
-# define POOL_EXTRA_MARK (0)
-# define POOL_DEBUG_SET_MARK(pool, item)   do { } while (0)
-# define POOL_DEBUG_RESET_MARK(pool, item) do { } while (0)
-# define POOL_DEBUG_CHECK_MARK(pool, item) do { } while (0)
-
-#endif // DEBUG_MEMORY_POOLS
-
 /* It's possible to trace callers of pool_free() by placing their pointer
  * after the end of the area and the optional mark above, which means the
  * end of the allocated array.
diff --git a/src/pool.c b/src/pool.c
index afe3d51204..b85a797a08 100644
--- a/src/pool.c
+++ b/src/pool.c
@@ -56,6 +56,9 @@ uint pool_debugging __read_mostly =               /* set of POOL_DBG_* flags */
 #endif
 #if defined(DEBUG_POOL_TRACING)
 	POOL_DBG_CALLER     |
+#endif
+#if defined(DEBUG_MEMORY_POOLS)
+	POOL_DBG_TAG        |
 #endif
 	0;
 
@@ -206,7 +209,7 @@ struct pool_head *create_pool(char *name, unsigned int size, unsigned int flags)
 	 * Note: for the LRU cache, we need to store 2 doubly-linked lists.
 	 */
 
-	extra_mark = POOL_EXTRA_MARK;
+	extra_mark = (pool_debugging & POOL_DBG_TAG) ? POOL_EXTRA_MARK : 0;
 	extra_caller = (pool_debugging & POOL_DBG_CALLER) ? POOL_EXTRA_CALLER : 0;
 	extra = extra_mark + extra_caller;