From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Fri, 1 Mar 2013 16:26:12 +0000 (-0500)
Subject: Fix: set wait/wake fd to -1 before close
X-Git-Tag: v2.2.0-rc1~67
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=c33ceb0250b3a51f7f53993e51e2032ddbe88fe2;p=lttng-ust.git

Fix: set wait/wake fd to -1 before close

Else triggers double-close race.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---

diff --git a/libringbuffer/shm.h b/libringbuffer/shm.h
index 3d22a313..a1ddc4cd 100644
--- a/libringbuffer/shm.h
+++ b/libringbuffer/shm.h
@@ -141,6 +141,7 @@ int shm_close_wait_fd(struct lttng_ust_shm_handle *handle,
 {
 	struct shm_object_table *table = handle->table;
 	struct shm_object *obj;
+	int wait_fd;
 	size_t index;
 	int ret;
 
@@ -148,14 +149,15 @@ int shm_close_wait_fd(struct lttng_ust_shm_handle *handle,
 	if (caa_unlikely(index >= table->allocated_len))
 		return -EPERM;
 	obj = &table->objects[index];
-	if (obj->wait_fd[0] < 0)
+	wait_fd = obj->wait_fd[0];
+	if (wait_fd < 0)
 		return -ENOENT;
-	ret = close(obj->wait_fd[0]);
+	obj->wait_fd[0] = -1;
+	ret = close(wait_fd);
 	if (ret) {
 		ret = -errno;
 		return ret;
 	}
-	obj->wait_fd[0] = -1;
 	return 0;
 }
 
@@ -165,6 +167,7 @@ int shm_close_wakeup_fd(struct lttng_ust_shm_handle *handle,
 {
 	struct shm_object_table *table = handle->table;
 	struct shm_object *obj;
+	int wakeup_fd;
 	size_t index;
 	int ret;
 
@@ -172,14 +175,15 @@ int shm_close_wakeup_fd(struct lttng_ust_shm_handle *handle,
 	if (caa_unlikely(index >= table->allocated_len))
 		return -EPERM;
 	obj = &table->objects[index];
-	if (obj->wait_fd[1] < 0)
+	wakeup_fd = obj->wait_fd[1];
+	if (wakeup_fd < 0)
 		return -ENOENT;
-	ret = close(obj->wait_fd[1]);
+	obj->wait_fd[1] = -1;
+	ret = close(wakeup_fd);
 	if (ret) {
 		ret = -errno;
 		return ret;
 	}
-	obj->wait_fd[1] = -1;
 	return 0;
 }