[PATCH 5/6] gdbserver/Linux: internal error when killing a process that is already gone

[Pedro Alves <palves@redhat.com>]

If the process disappears (e.g., killed with "kill -9" from the shell)
while it was stopped under GDBserver's control, and the GDBserver
tries to kill it, GDBserver asserts:

 (gdb) shell kill -9 23084
 (gdb) kill
 ...
 Killing process(es): 23084
 /home/pedro/gdb/mygit/src/gdb/gdbserver/linux-low.c:972: A problem internal to GDBserver has been detected.
 kill_wait_lwp: Assertion `res > 0' failed.
 ...

gdb/gdbserver/ChangeLog:
2015-03-06  Pedro Alves  <palves@redhat.com>

	* linux-low.c (kill_wait_lwp): Don't assert if waitpid fails.
	Instead, ignore ECHILD, and throw an error for other errnos.
---
 gdb/gdbserver/linux-low.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/gdb/gdbserver/linux-low.c b/gdb/gdbserver/linux-low.c
index f9c4079..e536a51 100644
--- a/gdb/gdbserver/linux-low.c
+++ b/gdb/gdbserver/linux-low.c
@@ -970,7 +970,10 @@ kill_wait_lwp (struct lwp_info *lwp)
 	res = my_waitpid (lwpid, &wstat, __WCLONE);
     } while (res > 0 && WIFSTOPPED (wstat));
 
-  gdb_assert (res > 0);
+  /* Even if it was stopped, the child may have already disappeared.
+     E.g., if it was killed by SIGKILL.  */
+  if (res < 0 && errno != ECHILD)
+    perror_with_name ("kill_wait_lwp");
 }
 
 /* Callback for `find_inferior'.  Kills an lwp of a given process,
-- 
1.9.3