fix gdbserver/linux-low'c's pending status handling

Another fix I'm working made schedlock.exp fail with gdbserver
frequently.  Looking deeper, it turns out to be a pre-existing bug.

status_pending_p_callback is filtering out LWPs incorrectly.  The
result is that that sometimes status_pending_p_callback returns a
pending event for an LWP that isn't expected, and then GDBserver gets
very confused.

E.g,. when doing a step-over, linux_wait_for_event is called with a
particular LWP's ptid, meaning events for all other LWPs should be
left pending, but here we see it retuning an event for some other LWP:

 linux_wait_1: [<all threads>]
 step_over_bkpt set [LWP 29577.29577], doing a blocking wait      <--------
 my_waitpid (-1, 0x40000001)
 my_waitpid (-1, 0x80000001): status(57f), 0
 LWFE: waitpid(-1, ...) returned 0, ERRNO-OK
 pc is 0x4007a0
 src/gdb/gdbserver/linux-low.c:2587: A problem internal to GDBserver has been detected.
 linux_wait_1: got event for 29581                                <--------

 Remote connection closed
 (gdb) FAIL: gdb.threads/schedlock.exp: continue to breakpoint: return to loop (initial)
 delete breakpoints

Tested on x86_64 Fedora 20.

gdb/gdbserver/ChangeLog:
2015-02-20  Pedro Alves  <palves@redhat.com>

	* linux-low.c (status_pending_p_callback): Use ptid_match.

diff --git a/gdb/gdbserver/ChangeLog b/gdb/gdbserver/ChangeLog
index 06848e089cf78d333cacb7ba9c18dc3b8c9cef05..cd79d75f79036313a2de0ec53267ce30244fc83b 100644 (file)
--- a/gdb/gdbserver/ChangeLog
+++ b/gdb/gdbserver/ChangeLog
@@ -1,3 +1,7 @@
+2015-02-20  Pedro Alves  <palves@redhat.com>
+
+       * linux-low.c (status_pending_p_callback): Use ptid_match.
+
 2015-02-19  Antoine Tremblay  <antoine.tremblay@ericsson.com>
 
        PR breakpoints/16812

diff --git a/gdb/gdbserver/linux-low.c b/gdb/gdbserver/linux-low.c
index 1869857d59002b910b1ed45e6affcf14b977df0c..a6e1e3dce5f3b3c3b32a1e3ce1d95ad3c05ce360 100644 (file)
--- a/gdb/gdbserver/linux-low.c
+++ b/gdb/gdbserver/linux-low.c
@@ -1288,9 +1288,8 @@ status_pending_p_callback (struct inferior_list_entry *entry, void *arg)
   ptid_t ptid = * (ptid_t *) arg;
 
   /* Check if we're only interested in events from a specific process
-     or its lwps.  */
-  if (!ptid_equal (minus_one_ptid, ptid)
-      && ptid_get_pid (ptid) != ptid_get_pid (thread->entry.id))
+     or a specific LWP.  */
+  if (!ptid_match (ptid_of (thread), ptid))
     return 0;
 
   if (lp->status_pending_p