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authorPaul Pluzhnikov <ppluzhnikov@google.com>2009-10-28 17:03:16 +0000
committerPaul Pluzhnikov <ppluzhnikov@google.com>2009-10-28 17:03:16 +0000
commit5f7d1694fc979b6091e367b9441330ffd0f6b0c5 (patch)
tree64b702a19bab212744284468d140d5b353ea376e /gdb/gdbserver
parent721a8186463bd0613adde0a0cfc46bb3c5d7bfdb (diff)
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2009-10-28 Paul Pluzhnikov <ppluzhnikov@google.com>
PR gdb/10757 * thread-db.c (attach_thread): New function. (maybe_attach_thread): Return success/failure. (find_new_threads_callback): Adjust. (thread_db_find_new_threads): Loop until no new threads.
Diffstat (limited to 'gdb/gdbserver')
-rw-r--r--gdb/gdbserver/ChangeLog8
-rw-r--r--gdb/gdbserver/thread-db.c77
2 files changed, 71 insertions, 14 deletions
diff --git a/gdb/gdbserver/ChangeLog b/gdb/gdbserver/ChangeLog
index 47a74b4..77a5d19 100644
--- a/gdb/gdbserver/ChangeLog
+++ b/gdb/gdbserver/ChangeLog
@@ -1,3 +1,11 @@
+2009-10-28 Paul Pluzhnikov <ppluzhnikov@google.com>
+
+ PR gdb/10757
+ * thread-db.c (attach_thread): New function.
+ (maybe_attach_thread): Return success/failure.
+ (find_new_threads_callback): Adjust.
+ (thread_db_find_new_threads): Loop until no new threads.
+
2009-10-13 Pedro Alves <pedro@codesourcery.com>
* proc-service.c (ps_lgetregs): Formatting.
diff --git a/gdb/gdbserver/thread-db.c b/gdb/gdbserver/thread-db.c
index 4d1008f..0fb8647 100644
--- a/gdb/gdbserver/thread-db.c
+++ b/gdb/gdbserver/thread-db.c
@@ -297,16 +297,13 @@ find_one_thread (ptid_t ptid)
return 1;
}
-static void
-maybe_attach_thread (const td_thrhandle_t *th_p, td_thrinfo_t *ti_p)
+/* Attach a thread. Return true on success. */
+
+static int
+attach_thread (const td_thrhandle_t *th_p, td_thrinfo_t *ti_p)
{
- td_err_e err;
struct lwp_info *lwp;
- lwp = find_lwp_pid (pid_to_ptid (ti_p->ti_lid));
- if (lwp != NULL)
- return;
-
if (debug_threads)
fprintf (stderr, "Attaching to thread %ld (LWP %d)\n",
ti_p->ti_tid, ti_p->ti_lid);
@@ -316,7 +313,7 @@ maybe_attach_thread (const td_thrhandle_t *th_p, td_thrinfo_t *ti_p)
{
warning ("Could not attach to thread %ld (LWP %d)\n",
ti_p->ti_tid, ti_p->ti_lid);
- return;
+ return 0;
}
lwp->thread_known = 1;
@@ -324,12 +321,39 @@ maybe_attach_thread (const td_thrhandle_t *th_p, td_thrinfo_t *ti_p)
if (thread_db_use_events)
{
+ td_err_e err;
struct thread_db *thread_db = current_process ()->private->thread_db;
+
err = thread_db->td_thr_event_enable_p (th_p, 1);
if (err != TD_OK)
error ("Cannot enable thread event reporting for %d: %s",
ti_p->ti_lid, thread_db_err_str (err));
}
+
+ return 1;
+}
+
+/* Attach thread if we haven't seen it yet.
+ Increment *COUNTER if we have attached a new thread.
+ Return false on failure. */
+
+static int
+maybe_attach_thread (const td_thrhandle_t *th_p, td_thrinfo_t *ti_p,
+ int *counter)
+{
+ struct lwp_info *lwp;
+
+ lwp = find_lwp_pid (pid_to_ptid (ti_p->ti_lid));
+ if (lwp != NULL)
+ return 1;
+
+ if (!attach_thread (th_p, ti_p))
+ return 0;
+
+ if (counter != NULL)
+ *counter += 1;
+
+ return 1;
}
static int
@@ -347,7 +371,12 @@ find_new_threads_callback (const td_thrhandle_t *th_p, void *data)
if (ti.ti_state == TD_THR_UNKNOWN || ti.ti_state == TD_THR_ZOMBIE)
return 0;
- maybe_attach_thread (th_p, &ti);
+ if (!maybe_attach_thread (th_p, &ti, (int *) data))
+ {
+ /* Terminate iteration early: we might be looking at stale data in
+ the inferior. The thread_db_find_new_threads will retry. */
+ return 1;
+ }
return 0;
}
@@ -358,6 +387,7 @@ thread_db_find_new_threads (void)
td_err_e err;
ptid_t ptid = ((struct inferior_list_entry *) current_inferior)->id;
struct thread_db *thread_db = current_process ()->private->thread_db;
+ int loop, iteration;
/* This function is only called when we first initialize thread_db.
First locate the initial thread. If it is not ready for
@@ -365,11 +395,30 @@ thread_db_find_new_threads (void)
if (find_one_thread (ptid) == 0)
return;
- /* Iterate over all user-space threads to discover new threads. */
- err = thread_db->td_ta_thr_iter_p (thread_db->thread_agent,
- find_new_threads_callback, NULL,
- TD_THR_ANY_STATE, TD_THR_LOWEST_PRIORITY,
- TD_SIGNO_MASK, TD_THR_ANY_USER_FLAGS);
+ /* Require 4 successive iterations which do not find any new threads.
+ The 4 is a heuristic: there is an inherent race here, and I have
+ seen that 2 iterations in a row are not always sufficient to
+ "capture" all threads. */
+ for (loop = 0, iteration = 0; loop < 4; ++loop, ++iteration)
+ {
+ int new_thread_count = 0;
+
+ /* Iterate over all user-space threads to discover new threads. */
+ err = thread_db->td_ta_thr_iter_p (thread_db->thread_agent,
+ find_new_threads_callback,
+ &new_thread_count,
+ TD_THR_ANY_STATE, TD_THR_LOWEST_PRIORITY,
+ TD_SIGNO_MASK, TD_THR_ANY_USER_FLAGS);
+ if (debug_threads)
+ fprintf (stderr, "Found %d threads in iteration %d.\n",
+ new_thread_count, iteration);
+
+ if (new_thread_count != 0)
+ {
+ /* Found new threads. Restart iteration from beginning. */
+ loop = -1;
+ }
+ }
if (err != TD_OK)
error ("Cannot find new threads: %s", thread_db_err_str (err));
}