From: Willy Tarreau <w@1wt.eu>
Date: Fri, 17 May 2019 12:16:51 +0000 (+0200)
Subject: MINOR: task: always reset curr_task when freeing a task or tasklet
X-Git-Tag: v2.0-dev4~67
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=29bf96d73dc7d369cde0d668e24c94f703c0ad32;p=thirdparty%2Fhaproxy.git

MINOR: task: always reset curr_task when freeing a task or tasklet

With the thread debugger it becomes visible that we can leave some
wandering pointers for a while in curr_task, which is inappropriate.
This patch addresses this by resetting curr_task to NULL before really
freeing the area. This way it becomes safe even regarding signals.
---

diff --git a/include/proto/task.h b/include/proto/task.h
index 34757f138f..0aea726305 100644
--- a/include/proto/task.h
+++ b/include/proto/task.h
@@ -319,11 +319,15 @@ static inline struct task *task_new(unsigned long thread_mask)
 }
 
 /*
- * Free a task. Its context must have been freed since it will be lost.
- * The task count is decremented.
+ * Free a task. Its context must have been freed since it will be lost. The
+ * task count is decremented. It it is the current task, this one is reset.
  */
 static inline void __task_free(struct task *t)
 {
+	if (t == curr_task) {
+		curr_task = NULL;
+		__ha_barrier_store();
+	}
 	pool_free(pool_head_task, t);
 	if (unlikely(stopping))
 		pool_flush(pool_head_task);
@@ -363,6 +367,10 @@ static inline void tasklet_free(struct tasklet *tl)
 		_HA_ATOMIC_SUB(&tasks_run_queue, 1);
 	}
 
+	if ((struct task *)tl == curr_task) {
+		curr_task = NULL;
+		__ha_barrier_store();
+	}
 	pool_free(pool_head_tasklet, tl);
 	if (unlikely(stopping))
 		pool_flush(pool_head_tasklet);