Re: [patch 2/2] Fix watchpoints for multi-inferior #2

Pedro Alves
2012-03-16T20:11:15Z

Here's what I'm applying. I've added comments inspired on your follow-up patch.

This makes watchpoint-multi.exp pass cleanly with the extended-remote
board, on x86_64 Fedora 16.

gdb/gdbserver/
2012-03-16 Pedro Alves <palves@redhat.com>
Jan Kratochvil <jan.kratochvil@redhat.com>

* server.c (cont_thread, general_thread): Add describing comments.
(start_inferior): Clear `cont_thread'.
(handle_v_cont): Don't set `cont_thread' if resuming all threads
of a process.
---

gdb/gdbserver/server.c | 24 ++++++++++++++++++++++--
1 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/gdb/gdbserver/server.c b/gdb/gdbserver/server.c
index 3c97dbd..a4e9e57 100644
--- a/gdb/gdbserver/server.c
+++ b/gdb/gdbserver/server.c
@@ -30,7 +30,19 @@
#include <sys/wait.h>
#endif

+/* The thread set with an `Hc' packet. `Hc' is deprecated in favor of
+ `vCont'. Note the multi-process extensions made `vCont' a
+ requirement, so `Hc pPID.TID' is pretty much undefined. So
+ CONT_THREAD can be null_ptid for no `Hc' thread, minus_one_ptid for
+ resuming all threads of the process (again, `Hc' isn't used for
+ multi-process), or a specific thread ptid_t.
+
+ We also set this when handling a single-thread `vCont' resume, as
+ some places in the backends check it to know when (and for which
+ thread) single-thread scheduler-locking is in effect. */
ptid_t cont_thread;
+
+/* The thread set with an `Hg' packet. */
ptid_t general_thread;

int server_waiting;
@@ -262,6 +274,10 @@ start_inferior (char **argv)
signal (SIGTTIN, SIG_DFL);
#endif

+ /* Clear this so the backend doesn't get confused, thinking
+ CONT_THREAD died, and it needs to resume all threads. */
+ cont_thread = null_ptid;
+
signal_pid = create_inferior (new_argv[0], new_argv);

/* FIXME: we don't actually know at this point that the create
@@ -1962,9 +1978,13 @@ handle_v_cont (char *own_buf)
if (i < n)
resume_info[i] = default_action;

- /* Still used in occasional places in the backend. */
+ /* `cont_thread' is still used in occasional places in the backend,
+ to implement single-thread scheduler-locking. Doesn't make sense
+ to set it if we see a stop request, or any form of wildcard
+ vCont. */
if (n == 1
- && !ptid_equal (resume_info[0].thread, minus_one_ptid)
+ && !(ptid_equal (resume_info[0].thread, minus_one_ptid)
+ || ptid_get_lwp (resume_info[0].thread) == -1)
&& resume_info[0].kind != resume_stop)
cont_thread = resume_info[0].thread;
else