Currently GDB never sends more than one action per vCont packet, when
connected in non-stop mode. A follow up patch will change that, and
it exposed a gdbserver problem with the vCont handling.
For example, this in non-stop mode:
=> vCont;s:p1.1;c
<= OK
Should be equivalent to:
=> vCont;s:p1.1
<= OK
=> vCont;c
<= OK
But gdbserver currently doesn't handle this. In the latter case,
"vCont;c" makes gdbserver clobber the previous step request. This
patch fixes that.
Note the server side must ignore resume actions for the thread that
has a pending %Stopped notification (and any other threads with events
pending), until GDB acks the notification with vStopped. Otherwise,
e.g., the following case is mishandled:
#1 => g (or any other packet)
#2 <= [registers]
#3 <= %Stopped T05 thread:p1.2
#4 => vCont s:p1.1;c
#5 <= OK
Above, the server must not resume thread p1.2 when it processes the
vCont. GDB can't know that p1.2 stopped until it acks the %Stopped
notification. (Otherwise it wouldn't send a default "c" action.)
(The vCont documentation already specifies this.)
Finally, special care must also be given to handling fork/vfork
events. A (v)fork event actually tells us that two processes stopped
-- the parent and the child. Until we follow the fork, we must not
resume the child. Therefore, if we have a pending fork follow, we
must not send a global wildcard resume action (vCont;c). We can still
send process-wide wildcards though.
(The comments above will be added as code comments to gdb in a follow
up patch.)
gdb/gdbserver/ChangeLog:
2016-02-16 Pedro Alves <palves@redhat.com>
* linux-low.c (linux_set_resume_request): Ignore resume requests
for already-resumed threads.
* server.c (in_queued_stop_replies_ptid, in_queued_stop_replies):
New functions.
* server.h (in_queued_stop_replies): New declaration.
---
gdb/gdbserver/linux-low.c | 27 +++++++++++++++++++++++++++
gdb/gdbserver/server.c | 33 ++++++++++++++++++++++++++++++++-
gdb/gdbserver/server.h | 4 ++++
3 files changed, 63 insertions(+), 1 deletion(-)
diff --git a/gdb/gdbserver/linux-low.c b/gdb/gdbserver/linux-low.c
index 8b025bd..2cac4c0 100644
--- a/gdb/gdbserver/linux-low.c
+++ b/gdb/gdbserver/linux-low.c
@@ -4465,6 +4465,33 @@ linux_set_resume_request (struct inferior_list_entry *entry, void *arg)
continue;
}
+ /* Ignore (wildcard) resume requests for already-resumed
+ requests. */