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Linux native thread create/exit events support
A following patch (fix for gdb/19828) makes linux-nat.c add threads to
GDB's thread list earlier in the "attach" sequence, and that causes a
surprising regression on
gdb.threads/attach-many-short-lived-threads.exp on my machine. The
extra "thread x exited" handling and traffic slows down that test
enough that GDB core has trouble keeping up with new threads that are
spawned while trying to stop existing ones.
I saw the exact same issue with remote/gdbserver a while ago and fixed
it in 65706a29ba (Remote thread create/exit events) so part of the
fix here is the exact same -- add support for thread created events to
gdb/linux-nat.c. infrun.c:stop_all_threads enables those events when
it tries to stop threads, which ensures that new threads never get a
chance to themselves start new threads, thus fixing the race.
gdb/
2016-05-24 Pedro Alves <palves@redhat.com>
PR gdb/19828
* linux-nat.c (report_thread_events): New global.
(linux_handle_extended_wait): Report
TARGET_WAITKIND_THREAD_CREATED if thread event reporting is
enabled.
(wait_lwp, linux_nat_filter_event): Report all thread exits if
thread event reporting is enabled. Remove comment.
(filter_exit_event): New function.
(linux_nat_wait_1): Use it.
(linux_nat_thread_events): New function.
(linux_nat_add_target): Install it as target_thread_events method.
This commit is contained in:
Pedro Alves
parent
44d3da2338
commit
aa01bd3689
@ -1,3 +1,17 @@
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2016-05-24 Pedro Alves <palves@redhat.com>
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PR gdb/19828
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* linux-nat.c (report_thread_events): New global.
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(linux_handle_extended_wait): Report
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TARGET_WAITKIND_THREAD_CREATED if thread event reporting is
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enabled.
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(wait_lwp, linux_nat_filter_event): Report all thread exits if
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thread event reporting is enabled. Remove comment.
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(filter_exit_event): New function.
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(linux_nat_wait_1): Use it.
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(linux_nat_thread_events): New function.
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(linux_nat_add_target): Install it as target_thread_events method.
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2016-05-24 Yan-Ting Lin <currygt52@gmail.com>
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* MAINTAINERS (Write After Approval): Add "Yan-Ting Lin".
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@ -239,6 +239,9 @@ struct simple_pid_list
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};
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struct simple_pid_list *stopped_pids;
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/* Whether target_thread_events is in effect. */
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static int report_thread_events;
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/* Async mode support. */
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/* The read/write ends of the pipe registered as waitable file in the
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@ -1952,6 +1955,11 @@ linux_handle_extended_wait (struct lwp_info *lp, int status)
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status_to_str (status));
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new_lp->status = status;
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}
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else if (report_thread_events)
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{
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new_lp->waitstatus.kind = TARGET_WAITKIND_THREAD_CREATED;
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new_lp->status = status;
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}
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return 1;
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}
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@ -2091,13 +2099,14 @@ wait_lwp (struct lwp_info *lp)
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/* Check if the thread has exited. */
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if (WIFEXITED (status) || WIFSIGNALED (status))
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{
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if (ptid_get_pid (lp->ptid) == ptid_get_lwp (lp->ptid))
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if (report_thread_events
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|| ptid_get_pid (lp->ptid) == ptid_get_lwp (lp->ptid))
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{
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if (debug_linux_nat)
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fprintf_unfiltered (gdb_stdlog, "WL: Process %d exited.\n",
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fprintf_unfiltered (gdb_stdlog, "WL: LWP %d exited.\n",
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ptid_get_pid (lp->ptid));
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/* This is the leader exiting, it means the whole
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/* If this is the leader exiting, it means the whole
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process is gone. Store the status to report to the
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core. Store it in lp->waitstatus, because lp->status
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would be ambiguous (W_EXITCODE(0,0) == 0). */
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@ -2902,7 +2911,8 @@ linux_nat_filter_event (int lwpid, int status)
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/* Check if the thread has exited. */
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if (WIFEXITED (status) || WIFSIGNALED (status))
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{
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if (num_lwps (ptid_get_pid (lp->ptid)) > 1)
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if (!report_thread_events
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&& num_lwps (ptid_get_pid (lp->ptid)) > 1)
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{
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if (debug_linux_nat)
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fprintf_unfiltered (gdb_stdlog,
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@ -2922,15 +2932,9 @@ linux_nat_filter_event (int lwpid, int status)
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resumed. */
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if (debug_linux_nat)
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fprintf_unfiltered (gdb_stdlog,
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"Process %ld exited (resumed=%d)\n",
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"LWP %ld exited (resumed=%d)\n",
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ptid_get_lwp (lp->ptid), lp->resumed);
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/* This was the last lwp in the process. Since events are
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serialized to GDB core, we may not be able report this one
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right now, but GDB core and the other target layers will want
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to be notified about the exit code/signal, leave the status
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pending for the next time we're able to report it. */
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/* Dead LWP's aren't expected to reported a pending sigstop. */
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lp->signalled = 0;
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@ -3110,6 +3114,30 @@ check_zombie_leaders (void)
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}
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}
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/* Convenience function that is called when the kernel reports an exit
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event. This decides whether to report the event to GDB as a
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process exit event, a thread exit event, or to suppress the
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event. */
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static ptid_t
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filter_exit_event (struct lwp_info *event_child,
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struct target_waitstatus *ourstatus)
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{
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ptid_t ptid = event_child->ptid;
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if (num_lwps (ptid_get_pid (ptid)) > 1)
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{
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if (report_thread_events)
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ourstatus->kind = TARGET_WAITKIND_THREAD_EXITED;
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else
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ourstatus->kind = TARGET_WAITKIND_IGNORE;
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exit_lwp (event_child);
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}
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return ptid;
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}
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static ptid_t
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linux_nat_wait_1 (struct target_ops *ops,
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ptid_t ptid, struct target_waitstatus *ourstatus,
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@ -3339,6 +3367,9 @@ linux_nat_wait_1 (struct target_ops *ops,
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else
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lp->core = linux_common_core_of_thread (lp->ptid);
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if (ourstatus->kind == TARGET_WAITKIND_EXITED)
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return filter_exit_event (lp, ourstatus);
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return lp->ptid;
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}
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@ -4614,6 +4645,14 @@ linux_nat_fileio_unlink (struct target_ops *self,
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return ret;
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}
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/* Implementation of the to_thread_events method. */
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static void
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linux_nat_thread_events (struct target_ops *ops, int enable)
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{
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report_thread_events = enable;
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}
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void
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linux_nat_add_target (struct target_ops *t)
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{
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@ -4646,6 +4685,7 @@ linux_nat_add_target (struct target_ops *t)
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t->to_supports_stopped_by_sw_breakpoint = linux_nat_supports_stopped_by_sw_breakpoint;
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t->to_stopped_by_hw_breakpoint = linux_nat_stopped_by_hw_breakpoint;
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t->to_supports_stopped_by_hw_breakpoint = linux_nat_supports_stopped_by_hw_breakpoint;
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t->to_thread_events = linux_nat_thread_events;
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t->to_can_async_p = linux_nat_can_async_p;
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t->to_is_async_p = linux_nat_is_async_p;
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@ -1116,12 +1116,14 @@ thread_db_wait (struct target_ops *ops,
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ptid = beneath->to_wait (beneath, ptid, ourstatus, options);
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if (ourstatus->kind == TARGET_WAITKIND_IGNORE)
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return ptid;
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if (ourstatus->kind == TARGET_WAITKIND_EXITED
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|| ourstatus->kind == TARGET_WAITKIND_SIGNALLED)
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switch (ourstatus->kind)
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{
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case TARGET_WAITKIND_IGNORE:
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case TARGET_WAITKIND_EXITED:
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case TARGET_WAITKIND_THREAD_EXITED:
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case TARGET_WAITKIND_SIGNALLED:
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return ptid;
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}
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info = get_thread_db_info (ptid_get_pid (ptid));
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