From: Willy Tarreau <w@1wt.eu>
Date: Wed, 23 Feb 2022 09:10:33 +0000 (+0100)
Subject: MINOR: pools: replace DEBUG_POOL_TRACING with runtime POOL_DBG_CALLER
X-Git-Tag: v2.6-dev2~75
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=0271822f17c05f1cec833b2ec325647725426ff3;p=thirdparty%2Fhaproxy.git

MINOR: pools: replace DEBUG_POOL_TRACING with runtime POOL_DBG_CALLER

This option used to allow to store a pointer to the caller of the last
pool_alloc() or pool_free() at the end of the area. Now that we can
compute the offsets at runtime, let's check it at run time and continue
the code simplification. In __pool_alloc() we now always calculate the
return address (which is quite cheap), and the POOL_DEBUG_TRACE_CALLER()
calls are conditionned on the status of debugging option.
---

diff --git a/include/haproxy/pool-t.h b/include/haproxy/pool-t.h
index a7b3dda783..b68a4ab4d3 100644
--- a/include/haproxy/pool-t.h
+++ b/include/haproxy/pool-t.h
@@ -47,6 +47,7 @@
 #define POOL_DBG_INTEGRITY  0x00000008  // perform integrity checks on cache
 #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
 
 
 /* This is the head of a thread-local cache */
diff --git a/include/haproxy/pool.h b/include/haproxy/pool.h
index 05511a1a25..b1a0c60dd0 100644
--- a/include/haproxy/pool.h
+++ b/include/haproxy/pool.h
@@ -90,23 +90,17 @@
  * after the end of the area and the optional mark above, which means the
  * end of the allocated array.
  */
-#if defined(DEBUG_POOL_TRACING)
 # define POOL_EXTRA_CALLER (sizeof(void *))
 # define POOL_DEBUG_TRACE_CALLER(pool, item, caller)			\
 	do {								\
 		typeof(pool) __p = (pool);				\
 		typeof(item) __i = (item);				\
 		typeof(caller) __c = (caller);				\
+		if (likely(!(pool_debugging & POOL_DBG_CALLER)))	\
+			break;						\
 		*(typeof(caller)*)(((char *)__i) + __p->alloc_sz - sizeof(void*)) = __c; \
 	} while (0)
 
-#else // DEBUG_POOL_TRACING
-
-# define POOL_EXTRA_CALLER (0)
-# define POOL_DEBUG_TRACE_CALLER(pool, item, caller)   do { } while (0)
-
-#endif
-
 /* poison each newly allocated area with this byte if >= 0 */
 extern int mem_poison_byte;
 
diff --git a/src/pool.c b/src/pool.c
index 0fb3f08b49..afe3d51204 100644
--- a/src/pool.c
+++ b/src/pool.c
@@ -53,6 +53,9 @@ uint pool_debugging __read_mostly =               /* set of POOL_DBG_* flags */
 #endif
 #ifndef CONFIG_HAP_POOLS
 	POOL_DBG_NO_CACHE   |
+#endif
+#if defined(DEBUG_POOL_TRACING)
+	POOL_DBG_CALLER     |
 #endif
 	0;
 
@@ -204,7 +207,7 @@ struct pool_head *create_pool(char *name, unsigned int size, unsigned int flags)
 	 */
 
 	extra_mark = POOL_EXTRA_MARK;
-	extra_caller = POOL_EXTRA_CALLER;
+	extra_caller = (pool_debugging & POOL_DBG_CALLER) ? POOL_EXTRA_CALLER : 0;
 	extra = extra_mark + extra_caller;
 
 	if (!(flags & MEM_F_EXACT)) {
@@ -679,15 +682,12 @@ void pool_gc(struct pool_head *pool_ctx)
 void *__pool_alloc(struct pool_head *pool, unsigned int flags)
 {
 	void *p = NULL;
-	void *caller = NULL;
+	void *caller = __builtin_return_address(0);
 
 	if (unlikely(pool_debugging & POOL_DBG_FAIL_ALLOC))
 		if (!(flags & POOL_F_NO_FAIL) && mem_should_fail(pool))
 			return NULL;
 
-#if defined(DEBUG_POOL_TRACING)
-	caller = __builtin_return_address(0);
-#endif
 	if (likely(!(pool_debugging & POOL_DBG_NO_CACHE)) && !p)
 		p = pool_get_from_cache(pool, caller);
 
@@ -709,11 +709,8 @@ void *__pool_alloc(struct pool_head *pool, unsigned int flags)
  */
 void __pool_free(struct pool_head *pool, void *ptr)
 {
-	const void *caller = NULL;
+	const void *caller = __builtin_return_address(0);
 
-#if defined(DEBUG_POOL_TRACING)
-	caller = __builtin_return_address(0);
-#endif
 	/* we'll get late corruption if we refill to the wrong pool or double-free */
 	POOL_DEBUG_CHECK_MARK(pool, ptr);
 	POOL_DEBUG_RESET_MARK(pool, ptr);