MINOR: thread: only use atomic ops to touch the flags

The thread flags are touched a little bit by other threads, e.g. the STUCK
flag may be set by other ones, and they're watched a little bit. As such
we need to use atomic ops only to manipulate them. Most places were already
using them, but here we generalize the practice. Only ha_thread_dump() does
not change because it's run under isolation.

include/haproxy/task.h

@@ -367,7 +367,7 @@ static inline void _tasklet_wakeup_on(struct tasklet *tl, int thr, const char *f
 	tl->debug.caller_idx = !tl->debug.caller_idx;
 	tl->debug.caller_file[tl->debug.caller_idx] = file;
 	tl->debug.caller_line[tl->debug.caller_idx] = line;
-	if (th_ctx->flags & TH_FL_TASK_PROFILING)
+	if (_HA_ATOMIC_LOAD(&th_ctx->flags) & TH_FL_TASK_PROFILING)
 		tl->call_date = now_mono_time();
 #endif
 	__tasklet_wakeup_on(tl, thr);
@@ -421,7 +421,7 @@ static inline void _task_instant_wakeup(struct task *t, unsigned int f, const ch
 	tl->debug.caller_idx = !tl->debug.caller_idx;
 	tl->debug.caller_file[tl->debug.caller_idx] = file;
 	tl->debug.caller_line[tl->debug.caller_idx] = line;
-	if (th_ctx->flags & TH_FL_TASK_PROFILING)
+	if (_HA_ATOMIC_LOAD(&th_ctx->flags) & TH_FL_TASK_PROFILING)
 		tl->call_date = now_mono_time();
 #endif
 	__tasklet_wakeup_on(tl, thr);

src/activity.c

@@ -383,7 +383,7 @@ void activity_count_runtime(uint32_t run_time)
 	 * profiling to "on" when automatic, and going back below the "down"
 	 * threshold switches to off. The forced modes don't check the load.
 	 */
-	if (!(th_ctx->flags & TH_FL_TASK_PROFILING)) {
+	if (!(_HA_ATOMIC_LOAD(&th_ctx->flags) & TH_FL_TASK_PROFILING)) {
 		if (unlikely((profiling & HA_PROF_TASKS_MASK) == HA_PROF_TASKS_ON ||
 		             ((profiling & HA_PROF_TASKS_MASK) == HA_PROF_TASKS_AON &&
 		             swrate_avg(run_time, TIME_STATS_SAMPLES) >= up)))

src/debug.c

@@ -154,6 +154,7 @@ void ha_backtrace_to_stderr(void)
  * The calling thread ID needs to be passed in <calling_tid> to display a star
  * in front of the calling thread's line (usually it's tid). Any stuck thread
  * is also prefixed with a '>'.
+ * It must be called under thread isolation.
  */
 void ha_thread_dump(struct buffer *buf, int thr, int calling_tid)
 {
@@ -1365,7 +1366,7 @@ void debug_handler(int sig, siginfo_t *si, void *arg)
 	 * if it didn't move.
 	 */
 	if (!((threads_harmless_mask|sleeping_thread_mask) & tid_bit))
-		th_ctx->flags |= TH_FL_STUCK;
+		_HA_ATOMIC_OR(&th_ctx->flags, TH_FL_STUCK);
 }
 
 static int init_debug_per_thread()

src/fd.c

@@ -472,7 +472,7 @@ int fd_update_events(int fd, uint evts)
 	uint new_flags, must_stop;
 	ulong rmask, tmask;
 
-	th_ctx->flags &= ~TH_FL_STUCK; // this thread is still running
+	_HA_ATOMIC_AND(&th_ctx->flags, ~TH_FL_STUCK); // this thread is still running
 
 	/* do nothing if the FD was taken over under us */
 	do {

src/listener.c

@@ -1135,7 +1135,7 @@ void listener_accept(struct listener *l)
 		}
 #endif
 
-		th_ctx->flags &= ~TH_FL_STUCK; // this thread is still running
+		_HA_ATOMIC_AND(&th_ctx->flags, ~TH_FL_STUCK); // this thread is still running
 	} /* end of for (max_accept--) */
 
  end:

src/task.c

@@ -241,7 +241,7 @@ void __task_wakeup(struct task *t)
 		t->rq.key += offset;
 	}
 
-	if (th_ctx->flags & TH_FL_TASK_PROFILING)
+	if (_HA_ATOMIC_LOAD(&th_ctx->flags) & TH_FL_TASK_PROFILING)
 		t->call_date = now_mono_time();
 
 	eb32_insert(root, &t->rq);
@@ -568,7 +568,7 @@ unsigned int run_tasks_from_lists(unsigned int budgets[])
 		process = t->process;
 		t->calls++;
 		th_ctx->current = t;
-		th_ctx->flags &= ~TH_FL_STUCK; // this thread is still running
+		_HA_ATOMIC_AND(&th_ctx->flags, ~TH_FL_STUCK); // this thread is still running
 
 		_HA_ATOMIC_DEC(&th_ctx->rq_total);
 
@@ -578,7 +578,7 @@ unsigned int run_tasks_from_lists(unsigned int budgets[])
 			LIST_DEL_INIT(&((struct tasklet *)t)->list);
 			__ha_barrier_store();
 
-			if (unlikely(th_ctx->flags & TH_FL_TASK_PROFILING)) {
+			if (unlikely(_HA_ATOMIC_LOAD(&th_ctx->flags) & TH_FL_TASK_PROFILING)) {
 				profile_entry = sched_activity_entry(sched_activity, t->process);
 				before = now_mono_time();
 #ifdef DEBUG_TASK
@@ -603,7 +603,7 @@ unsigned int run_tasks_from_lists(unsigned int budgets[])
 				continue;
 			}
 
-			if (unlikely(th_ctx->flags & TH_FL_TASK_PROFILING)) {
+			if (unlikely(_HA_ATOMIC_LOAD(&th_ctx->flags) & TH_FL_TASK_PROFILING)) {
 				HA_ATOMIC_INC(&profile_entry->calls);
 				HA_ATOMIC_ADD(&profile_entry->cpu_time, now_mono_time() - before);
 			}
@@ -734,7 +734,7 @@ void process_runnable_tasks()
 	int heavy_queued = 0;
 	int budget;
 
-	th_ctx->flags &= ~TH_FL_STUCK; // this thread is still running
+	_HA_ATOMIC_AND(&th_ctx->flags, ~TH_FL_STUCK); // this thread is still running
 
 	if (!thread_has_tasks()) {
 		activity[tid].empty_rq++;

src/wdt.c

@@ -99,7 +99,7 @@ void wdt_handler(int sig, siginfo_t *si, void *arg)
 		 * If it's already set, then it's our second call with no
 		 * progress and the thread is dead.
 		 */
-		if (!(ha_thread_ctx[thr].flags & TH_FL_STUCK)) {
+		if (!(_HA_ATOMIC_LOAD(&ha_thread_ctx[thr].flags) & TH_FL_STUCK)) {
 			_HA_ATOMIC_OR(&ha_thread_ctx[thr].flags, TH_FL_STUCK);
 			goto update_and_leave;
 		}