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author | Pedro Alves <palves@redhat.com> | 2016-10-26 16:17:25 +0100 |
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committer | Pedro Alves <palves@redhat.com> | 2016-10-26 16:22:27 +0100 |
commit | 5a04c4cf5df6d13596e79e7b84520cbe245a5a4d (patch) | |
tree | ca918346659ecfe5cc666db371950a9b98b15544 /gdb/maint.c | |
parent | ca6eff59089ff1a1772ac95d4890f94b3eef2796 (diff) | |
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gdbserver: Leave already-vCont-resumed threads as they were
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:
2016-10-26 Pedro Alves <palves@redhat.com>
* linux-low.c (handle_extended_wait): Link parent/child fork
threads.
(linux_wait_1): Unlink them.
(linux_set_resume_request): Ignore resume requests for
already-resumed and unhandled fork child threads.
* linux-low.h (struct lwp_info) <fork_relative>: New field.
* server.c (in_queued_stop_replies_ptid, in_queued_stop_replies):
New functions.
(handle_v_requests) <vCont>: Don't call require_running.
* server.h (in_queued_stop_replies): New declaration.
Diffstat (limited to 'gdb/maint.c')
0 files changed, 0 insertions, 0 deletions