RTOS: Unify wipe-out of thread list

Each RTOS implementation uses it's own (similar) code to free
the thread list. There are some additional issues:

<--->
if (pointer != NULL)
	free(pointer);
<--->
This is not necessary, free(NULL) is perfectly ok.

<--->
free(rtos->thread_details);
rtos->thread_details = NULL;
rtos->thread_count = 0;
<--->
The 3rd line has been missing for all RTOS but ChibiOs. There are paths
in the code where rtos->thread_count is never set to NULL, which can
lead to null pointer dereference of rtos->thread_details.

Change-Id: I6f7045c3d4518b925cb80dd5c907a566536b34ad
Signed-off-by: Christian Eggers <ceggers@gmx.de>
---
Changelog:
v7:
- rtos_wipe_threadlist() --> rtos_free_threadlist()
- removed non related changes in gdb_server.c from this patch
v3:
- Removed world "topic" from first line of commit message
v2:
- typo: "whipe" --> "wipe"
Reviewed-on: http://openocd.zylin.com/1916
Tested-by: jenkins
Reviewed-by: Spencer Oliver <spen@spen-soft.co.uk>

src/rtos/ChibiOS.c

@@ -296,21 +296,8 @@ static int ChibiOS_update_threads(struct rtos *rtos)
 	}
 
 	/* wipe out previous thread details if any */
-	int j;
-	if (rtos->thread_details) {
-		for (j = 0; j < rtos->thread_count; j++) {
-			struct thread_detail *current_thread = &rtos->thread_details[j];
-			if (current_thread->display_str != NULL)
-				free(current_thread->display_str);
-			if (current_thread->thread_name_str != NULL)
-				free(current_thread->thread_name_str);
-			if (current_thread->extra_info_str != NULL)
-				free(current_thread->extra_info_str);
-		}
-		free(rtos->thread_details);
-		rtos->thread_details = NULL;
-		rtos->thread_count = 0;
-	}
+	rtos_free_threadlist(rtos);
+
 	/* ChibiOS does not save the current thread count. We have to first
 	 * parse the double linked thread list to check for errors and the number of
 	 * threads. */

src/rtos/FreeRTOS.c

@@ -173,25 +173,7 @@ static int FreeRTOS_update_threads(struct rtos *rtos)
 	}
 
 	/* wipe out previous thread details if any */
-	if (rtos->thread_details != NULL) {
-		int j;
-		for (j = 0; j < rtos->thread_count; j++) {
-			if (rtos->thread_details[j].display_str != NULL) {
-				free(rtos->thread_details[j].display_str);
-				rtos->thread_details[j].display_str = NULL;
-			}
-			if (rtos->thread_details[j].thread_name_str != NULL) {
-				free(rtos->thread_details[j].thread_name_str);
-				rtos->thread_details[j].thread_name_str = NULL;
-			}
-			if (rtos->thread_details[j].extra_info_str != NULL) {
-				free(rtos->thread_details[j].extra_info_str);
-				rtos->thread_details[j].extra_info_str = NULL;
-			}
-		}
-		free(rtos->thread_details);
-		rtos->thread_details = NULL;
-	}
+	rtos_free_threadlist(rtos);
 
 	/* read the current thread */
 	retval = target_read_buffer(rtos->target,

src/rtos/ThreadX.c

@@ -155,25 +155,7 @@ static int ThreadX_update_threads(struct rtos *rtos)
 	}
 
 	/* wipe out previous thread details if any */
-	if (rtos->thread_details != NULL) {
-		int j;
-		for (j = 0; j < rtos->thread_count; j++) {
-			if (rtos->thread_details[j].display_str != NULL) {
-				free(rtos->thread_details[j].display_str);
-				rtos->thread_details[j].display_str = NULL;
-			}
-			if (rtos->thread_details[j].thread_name_str != NULL) {
-				free(rtos->thread_details[j].thread_name_str);
-				rtos->thread_details[j].thread_name_str = NULL;
-			}
-			if (rtos->thread_details[j].extra_info_str != NULL) {
-				free(rtos->thread_details[j].extra_info_str);
-				rtos->thread_details[j].extra_info_str = NULL;
-			}
-		}
-		free(rtos->thread_details);
-		rtos->thread_details = NULL;
-	}
+	rtos_free_threadlist(rtos);
 
 	/* read the current thread id */
 	retval = target_read_buffer(rtos->target,

src/rtos/eCos.c

@@ -125,25 +125,7 @@ static int eCos_update_threads(struct rtos *rtos)
 	}
 
 	/* wipe out previous thread details if any */
-	if (rtos->thread_details != NULL) {
-		int j;
-		for (j = 0; j < rtos->thread_count; j++) {
-			if (rtos->thread_details[j].display_str != NULL) {
-				free(rtos->thread_details[j].display_str);
-				rtos->thread_details[j].display_str = NULL;
-			}
-			if (rtos->thread_details[j].thread_name_str != NULL) {
-				free(rtos->thread_details[j].thread_name_str);
-				rtos->thread_details[j].thread_name_str = NULL;
-			}
-			if (rtos->thread_details[j].extra_info_str != NULL) {
-				free(rtos->thread_details[j].extra_info_str);
-				rtos->thread_details[j].extra_info_str = NULL;
-			}
-		}
-		free(rtos->thread_details);
-		rtos->thread_details = NULL;
-	}
+	rtos_free_threadlist(rtos);
 
 	/* determine the number of current threads */
 	uint32_t thread_list_head = rtos->symbols[eCos_VAL_thread_list].address;

src/rtos/embKernel.c

@@ -206,25 +206,7 @@ static int embKernel_update_threads(struct rtos *rtos)
 	}
 
 	/* wipe out previous thread details if any */
-	if (rtos->thread_details != NULL) {
-		int j;
-		for (j = 0; j < rtos->thread_count; j++) {
-			if (rtos->thread_details[j].display_str != NULL) {
-				free(rtos->thread_details[j].display_str);
-				rtos->thread_details[j].display_str = NULL;
-			}
-			if (rtos->thread_details[j].thread_name_str != NULL) {
-				free(rtos->thread_details[j].thread_name_str);
-				rtos->thread_details[j].thread_name_str = NULL;
-			}
-			if (rtos->thread_details[j].extra_info_str != NULL) {
-				free(rtos->thread_details[j].extra_info_str);
-				rtos->thread_details[j].extra_info_str = NULL;
-			}
-		}
-		free(rtos->thread_details);
-		rtos->thread_details = NULL;
-	}
+	rtos_free_threadlist(rtos);
 
 	param = (const struct embKernel_params *) rtos->rtos_specific_params;
 

src/rtos/rtos.c

@@ -513,3 +513,20 @@ int rtos_update_threads(struct target *target)
 		target->rtos->type->update_threads(target->rtos);
 	return ERROR_OK;
 }
+
+void rtos_free_threadlist(struct rtos *rtos)
+{
+	if (rtos->thread_details) {
+		int j;
+
+		for (j = 0; j < rtos->thread_count; j++) {
+			struct thread_detail *current_thread = &rtos->thread_details[j];
+			free(current_thread->display_str);
+			free(current_thread->thread_name_str);
+			free(current_thread->extra_info_str);
+		}
+		free(rtos->thread_details);
+		rtos->thread_details = NULL;
+		rtos->thread_count = 0;
+	}
+}

src/rtos/rtos.h

@@ -98,6 +98,7 @@ int rtos_try_next(struct target *target);
 int gdb_thread_packet(struct connection *connection, char *packet, int packet_size);
 int rtos_get_gdb_reg_list(struct connection *connection);
 int rtos_update_threads(struct target *target);
+void rtos_free_threadlist(struct rtos *rtos);
 int rtos_smp_init(struct target *target);
 /*  function for handling symbol access */
 int rtos_qsymbol(struct connection *connection, char *packet, int packet_size);