Make init_spin_delay() C89 compliant and change stuck spinlock reporting.

The current definition of init_spin_delay (introduced recently in
48354581a) wasn't C89 compliant. It's not legal to refer to refer to
non-constant expressions, and the ptr argument was one.  This, as
reported by Tom, lead to a failure on buildfarm animal pademelon.

The pointer, especially on system systems with ASLR, isn't super helpful
anyway, though. So instead of making init_spin_delay into an inline
function, make s_lock_stuck() report the function name in addition to
file:line and change init_spin_delay() accordingly. While not a direct
replacement, the function name is likely more useful anyway (line
numbers are often hard to interpret in third party reports).

This also fixes what file/line number is reported for waits via
s_lock().

As PG_FUNCNAME_MACRO is now used outside of elog.h, move it to c.h.

Reported-By: Tom Lane
Discussion: 4369.1460435533@sss.pgh.pa.us

src/backend/storage/buffer/bufmgr.c

@@ -4029,7 +4029,7 @@ rnode_comparator(const void *p1, const void *p2)
 uint32
 LockBufHdr(BufferDesc *desc)
 {
-	SpinDelayStatus delayStatus = init_spin_delay(desc);
+	SpinDelayStatus delayStatus = init_local_spin_delay();
 	uint32		old_buf_state;
 
 	while (true)
@@ -4055,7 +4055,7 @@ LockBufHdr(BufferDesc *desc)
 static uint32
 WaitBufHdrUnlocked(BufferDesc *buf)
 {
-	SpinDelayStatus delayStatus = init_spin_delay(buf);
+	SpinDelayStatus delayStatus = init_local_spin_delay();
 	uint32		buf_state;
 
 	buf_state = pg_atomic_read_u32(&buf->state);

src/backend/storage/lmgr/lwlock.c

@@ -870,7 +870,7 @@ LWLockWaitListLock(LWLock *lock)
 
 		/* and then spin without atomic operations until lock is released */
 		{
-			SpinDelayStatus delayStatus = init_spin_delay(&lock->state);
+			SpinDelayStatus delayStatus = init_local_spin_delay();
 
 			while (old_state & LW_FLAG_LOCKED)
 			{

src/backend/storage/lmgr/s_lock.c

@@ -70,16 +70,18 @@ static int	spins_per_delay = DEFAULT_SPINS_PER_DELAY;
  * s_lock_stuck() - complain about a stuck spinlock
  */
 static void
-s_lock_stuck(void *p, const char *file, int line)
+s_lock_stuck(const char *file, int line, const char *func)
 {
+	if (!func)
+		func = "(unknown)";
 #if defined(S_LOCK_TEST)
 	fprintf(stderr,
-			"\nStuck spinlock (%p) detected at %s:%d.\n",
-			p, file, line);
+			"\nStuck spinlock detected at %s, %s:%d.\n",
+			func, file, line);
 	exit(1);
 #else
-	elog(PANIC, "stuck spinlock (%p) detected at %s:%d",
-		 p, file, line);
+	elog(PANIC, "stuck spinlock detected at %s, %s:%d",
+		 func, file, line);
 #endif
 }
 
@@ -87,9 +89,9 @@ s_lock_stuck(void *p, const char *file, int line)
  * s_lock(lock) - platform-independent portion of waiting for a spinlock.
  */
 int
-s_lock(volatile slock_t *lock, const char *file, int line)
+s_lock(volatile slock_t *lock, const char *file, int line, const char *func)
 {
-	SpinDelayStatus delayStatus = init_spin_delay((void *) lock);
+	SpinDelayStatus delayStatus = init_spin_delay(file, line, func);
 
 	while (TAS_SPIN(lock))
 	{
@@ -127,7 +129,7 @@ perform_spin_delay(SpinDelayStatus *status)
 	if (++(status->spins) >= spins_per_delay)
 	{
 		if (++(status->delays) > NUM_DELAYS)
-			s_lock_stuck(status->ptr, status->file, status->line);
+			s_lock_stuck(status->file, status->line, status->func);
 
 		if (status->cur_delay == 0)		/* first time to delay? */
 			status->cur_delay = MIN_DELAY_USEC;

src/include/c.h

@@ -169,6 +169,17 @@
 #define dummyret	char
 #endif
 
+/* Which __func__ symbol do we have, if any? */
+#ifdef HAVE_FUNCNAME__FUNC
+#define PG_FUNCNAME_MACRO	__func__
+#else
+#ifdef HAVE_FUNCNAME__FUNCTION
+#define PG_FUNCNAME_MACRO	__FUNCTION__
+#else
+#define PG_FUNCNAME_MACRO	NULL
+#endif
+#endif
+
 /* ----------------------------------------------------------------
  *				Section 2:	bool, true, false, TRUE, FALSE, NULL
  * ----------------------------------------------------------------

src/include/storage/s_lock.h

@@ -930,7 +930,7 @@ extern int	tas_sema(volatile slock_t *lock);
 
 #if !defined(S_LOCK)
 #define S_LOCK(lock) \
-	(TAS(lock) ? s_lock((lock), __FILE__, __LINE__) : 0)
+	(TAS(lock) ? s_lock((lock), __FILE__, __LINE__, PG_FUNCNAME_MACRO) : 0)
 #endif	 /* S_LOCK */
 
 #if !defined(S_LOCK_FREE)
@@ -983,7 +983,7 @@ extern slock_t dummy_spinlock;
 /*
  * Platform-independent out-of-line support routines
  */
-extern int s_lock(volatile slock_t *lock, const char *file, int line);
+extern int s_lock(volatile slock_t *lock, const char *file, int line, const char *func);
 
 /* Support for dynamic adjustment of spins_per_delay */
 #define DEFAULT_SPINS_PER_DELAY  100
@@ -1000,12 +1000,13 @@ typedef struct
 	int			spins;
 	int			delays;
 	int			cur_delay;
-	void	   *ptr;
 	const char *file;
 	int			line;
+	const char *func;
 } SpinDelayStatus;
 
-#define init_spin_delay(ptr) {0, 0, 0, (ptr), __FILE__, __LINE__}
+#define init_spin_delay(file, line, func) {0, 0, 0, file, line, func}
+#define init_local_spin_delay() init_spin_delay(__FILE__, __LINE__, PG_FUNCNAME_MACRO)
 void perform_spin_delay(SpinDelayStatus *status);
 void finish_spin_delay(SpinDelayStatus *status);
 

src/include/utils/elog.h

@@ -71,18 +71,6 @@
 #include "utils/errcodes.h"
 
 
-/* Which __func__ symbol do we have, if any? */
-#ifdef HAVE_FUNCNAME__FUNC
-#define PG_FUNCNAME_MACRO	__func__
-#else
-#ifdef HAVE_FUNCNAME__FUNCTION
-#define PG_FUNCNAME_MACRO	__FUNCTION__
-#else
-#define PG_FUNCNAME_MACRO	NULL
-#endif
-#endif
-
-
 /*----------
  * New-style error reporting API: to be used in this way:
  *		ereport(ERROR,