[PATCH v4 8/9] fix py-finish-breakpoint.exp with always-async

Tom Tromey
2013-10-22T18:11:56Z

With target async enabled, py-finish-breakpoint.exp will trigger an
assertion failure.

The failure occurs because execute_command re-enters the event loop in
some circumstances, and in this case resets the sync_execution flag.
Then later gdb reaches this assertion in normal_stop:

gdb_assert (sync_execution || !target_can_async_p ());

execute_command has a comment explaining why it dispatches events:

/* If the interpreter is in sync mode (we're running a user
command's list, running command hooks or similars), and we
just ran a synchronous command that started the target, wait
for that command to end. */

However, the code did not follow this comment -- it didn't check to
see if the command started the target, just whether the target was
executing a sync command at this point.

This patch fixes the problem by noting whether the target was
executing in sync_execution mode before running the command, and then
augmenting the condition to test this as well.

Built and regtested on x86-64 Fedora 18.

PR gdb/14135:
* top.c (execute_command): Only dispatch events if command
started target.
---
gdb/top.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/gdb/top.c b/gdb/top.c
index c473d8c..b563eca 100644
--- a/gdb/top.c
+++ b/gdb/top.c
@@ -415,6 +415,8 @@ execute_command (char *p, int from_tty)
{
const char *cmd = p;
char *arg;
+ int was_sync = sync_execution;
+
line = p;

/* If trace-commands is set then this will print this command. */
@@ -470,7 +472,7 @@ execute_command (char *p, int from_tty)
command's list, running command hooks or similars), and we
just ran a synchronous command that started the target, wait
for that command to end. */
- if (!interpreter_async && sync_execution)
+ if (!interpreter_async && !was_sync && sync_execution)
{
while (gdb_do_one_event () >= 0)
if (!sync_execution)
--
1.8.1.4