If a tracepoint's actions list includes a while-stepping action, and
then the actions are changed to a list without any while-stepping
action, the tracepoint's step_count will be left with a stale value.
For example:
(gdb) trace subr
Tracepoint 1 at 0x4004d9: file ../../../src/gdb/testsuite//actions-changed.c, line 31.
(gdb) actions
Enter actions for tracepoint 1, one per line.
End with a line saying just "end".
>collect $reg
>end
(gdb) set debug remote 1
(gdb) tstart
Sending packet: $QTinit#59...Packet received: OK
Sending packet: $QTDP:1:00000000004004d9:E:0:0-#a3...Packet received: OK
Sending packet: $QTDP👎00000000004004d9:R03FFFFFFFFFFFFFFFFFF#2b...Packet received: OK
(gdb) tstop
Sending packet: $QTStop#4b...Packet received: OK
Sending packet: $QTNotes:#e8...Packet received: OK
(gdb) actions
Enter actions for tracepoint 1, one per line.
End with a line saying just "end".
>collect $reg
>while-stepping 1
>collect $reg
>end
>end
(gdb) tstart
Sending packet: $QTinit#59...Packet received: OK
Sending packet: $QTDP:1:00000000004004d9:E:1:0-#a4...Packet received: OK
Sending packet: $QTDP👎00000000004004d9:R03FFFFFFFFFFFFFFFFFF-#58...Packet received: OK
Sending packet: $QTDP👎00000000004004d9:SR03FFFFFFFFFFFFFFFFFF#7e...Packet received: OK
(gdb) tstop
Sending packet: $QTStop#4b...Packet received: OK
Sending packet: $QTNotes:#e8...Packet received: OK
(gdb) actions
Enter actions for tracepoint 1, one per line.
End with a line saying just "end".
>collect $regs
>end
(gdb) tstart
Sending packet: $QTinit#59...Packet received: OK
Sending packet: $QTDP:1:00000000004004d9:E:1:0-#a4...Packet received: OK
Sending packet: $QTDP👎00000000004004d9:R03FFFFFFFFFFFFFFFFFF#2b...Packet received: OK
The last "$QTDP:1:00000000004004d9:E:1:0-#a4" should be "$QTDP:1:00000000004004d9:E:0:0-#a3".
In pseudo-diff:
-$QTDP:1:00000000004004d9:E:1:0-#a4
+$QTDP:1:00000000004004d9:E:0:0-#a3
A related issue is that the "commands" command actually supports
setting commands to a range of breakpoints/tracepoints at once. But,
hacking "maint info breakpoints" to print t->step_count, reveals:
(gdb) trace main
Tracepoint 5 at 0x45a2ab: file ../../src/gdb/gdb.c, line 29.
(gdb) trace main
Note: breakpoint 5 also set at pc 0x45a2ab.
Tracepoint 6 at 0x45a2ab: file ../../src/gdb/gdb.c, line 29.
(gdb) commands 5-6
Type commands for breakpoint(s) 5-6, one per line.
End with a line saying just "end".
> while-stepping 5
>end
> end
(gdb) maint info breakpoints 5
Num Type Disp Enb Address What
5 tracepoint keep y 0x000000000045a2ab in main at ../../src/gdb/gdb.c:29 inf 1
step_count=5
^^^^^^^^^^^^
while-stepping 5
end
not installed on target
(gdb) maint info breakpoints 6
Num Type Disp Enb Address What
6 tracepoint keep y 0x000000000045a2ab in main at ../../src/gdb/gdb.c:29 inf 1
step_count=0
^^^^^^^^^^^^
while-stepping 5
end
not installed on target
(gdb)
that tracepoint 6 doesn't end up with the correct step_count.
The issue is that here:
static void
do_map_commands_command (struct breakpoint *b, void *data)
{
struct commands_info *info = data;
if (info->cmd == NULL)
{
struct command_line *l;
if (info->control != NULL)
l = copy_command_lines (info->control->body_list[0]);
else
{
struct cleanup *old_chain;
char *str;
str = xstrprintf (_("Type commands for breakpoint(s) "
"%s, one per line."),
info->arg);
old_chain = make_cleanup (xfree, str);
l = read_command_lines (str,
info->from_tty, 1,
(is_tracepoint (b)
? check_tracepoint_command : 0),
b);
do_cleanups (old_chain);
}
info->cmd = alloc_counted_command_line (l);
}
validate_actionline is never called for tracepoints other than the
first (the copy_command_lines path). Right below, we have:
/* If a breakpoint was on the list more than once, we don't need to
do anything. */
if (b->commands != info->cmd)
{
validate_commands_for_breakpoint (b, info->cmd->commands);
incref_counted_command_line (info->cmd);
decref_counted_command_line (&b->commands);
b->commands = info->cmd;
observer_notify_breakpoint_modified (b);
}
And validate_commands_for_breakpoint looks like the right place to put
a call; if we reset step_count there too, we have a nice central fix
for the first issue as well, because trace_actions_command calls
breakpoint_set_commands that also calls
validate_commands_for_breakpoint.
We end up calling validate_actionline twice for the first tracepoint,
since read_command_lines calls it too, through
check_tracepoint_command, but that should be harmless.
2013-04-04 Pedro Alves <palves@redhat.com>
Hui Zhu <hui@codesourcery.com>
* breakpoint.c (validate_commands_for_breakpoint): If validating a
tracepoint, reset its STEP_COUNT and call validate_actionline.
2013-04-04 Stan Shebs <stan@codesourcery.com>
Pedro Alves <palves@redhat.com>
* gdb.trace/Makefile.in (PROGS): Add actions-changed.
* gdb.trace/actions-changed.c: New file.
* gdb.trace/actions-changed.exp: New file.
* lib/trace-support.exp (gdb_trace_setactions): Rename to ...
(gdb_trace_setactions_command): ... this. Add "actions_command"
parameter, and handle it.
(gdb_trace_setactions, gdb_trace_setcommands): New procedures.
Joel Brobecker
Pedro Alves