[PATCH 03/18] remote.c/all-stop: Implement TARGET_WAITKIND_NO_RESUMED and TARGET_WNOHANG

Pedro Alves
2015-05-21T23:19:23Z

Even though "target remote" supports target-async, the all-stop
target_wait implementation ignores TARGET_WNOHANG. If the core
happens to poll for events and we've already read the stop reply out
of the serial/socket, remote_wait_as hangs forever instead of
returning an indication that there are no events to process. This
can't happen currently, but later changes will trigger this.

gdb/ChangeLog:
2015-05-21 Pedro Alves <palves@redhat.com>

* remote.c (remote_wait_as): If not waiting for a stop reply,
return TARGET_WAITKIND_NO_RESUMED. If TARGET_WNOHANG is
requested, don't block waiting forever.
---
gdb/remote.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/gdb/remote.c b/gdb/remote.c
index dfe115b..db06def 100644
--- a/gdb/remote.c
+++ b/gdb/remote.c
@@ -6227,6 +6227,14 @@ remote_wait_as (ptid_t ptid, struct target_waitstatus *status, int options)
{
int ret;
int is_notif;
+ int forever = ((options & TARGET_WNOHANG) == 0
+ && wait_forever_enabled_p);
+
+ if (!rs->waiting_for_stop_reply)
+ {
+ status->kind = TARGET_WAITKIND_NO_RESUMED;
+ return minus_one_ptid;
+ }

if (!target_is_async_p ())
{
@@ -6245,7 +6253,7 @@ remote_wait_as (ptid_t ptid, struct target_waitstatus *status, int options)
However, before we do that we need to ensure that the caller
knows how to take the target into/out of async mode. */
ret = getpkt_or_notif_sane (&rs->buf, &rs->buf_size,
- wait_forever_enabled_p, &is_notif);
+ forever, &is_notif);

if (!target_is_async_p ())
signal (SIGINT, ofunc);
@@ -6254,6 +6262,9 @@ remote_wait_as (ptid_t ptid, struct target_waitstatus *status, int options)
not interesting. */
if (ret != -1 && is_notif)
return minus_one_ptid;
+
+ if (ret == -1 && (options & TARGET_WNOHANG) != 0)
+ return minus_one_ptid;
}

buf = rs->buf;
--
1.9.3