[patch] Fix remote.c crash on gdbserver close (+fix py-finish-breakpoint.exp for gdbserver) [rediff]

[Jan Kratochvil <jan.kratochvil@redhat.com>]

[rediff on top of HEAD]

On Sun, 25 Dec 2011 12:37:45 +0100, Jan Kratochvil wrote:
Hi,

with gdbserver as from
	http://sourceware.org/gdb/wiki/TestingGDB#Testing_gdbserver_in_a_native_configuration

it will crash:

(gdb) PASS: gdb.python/py-finish-breakpoint.exp: set FinishBP after the exit()
continue
Continuing.
Child exited with status 0
GDBserver exiting
[Inferior 1 (Remote target) exited normally]
SimpleFinishBreakpoint out of scope
ERROR: Process no longer exists
Program terminated with signal 11, Segmentation fault.
#0  0x00000000007d48b9 in serial_debug_p (scb=0x0) at serial.c:584
584       return scb->debug_p || global_serial_debug_p;
(gdb) p scb
$1 = (struct serial *) 0x0
(gdb) bt
#0  in serial_debug_p (scb=0x0) at serial.c:584
#1  in serial_write (scb=0x0, str=0x7fff727e3300 "$z0,4008a3,1#93", len=15) at serial.c:427
#2  in putpkt_binary (buf=0x2a279b0 "z0,4008a3,1", cnt=11) at remote.c:6891
#3  in putpkt (buf=0x2a279b0 "z0,4008a3,1") at remote.c:6823
#4  in remote_remove_breakpoint (gdbarch=0x28e10f0, bp_tgt=0x2fb3d38) at remote.c:7749
#5  in target_remove_breakpoint (gdbarch=0x28e10f0, bp_tgt=0x2fb3d38) at target.c:2422
#6  in bkpt_remove_location (bl=0x2fb3cd0) at breakpoint.c:10967
#7  in remove_breakpoint_1 (bl=0x2fb3cd0, is=mark_uninserted) at breakpoint.c:2654
#8  in remove_breakpoint (bl=0x2fb3cd0, is=mark_uninserted) at breakpoint.c:2760
#9  in update_global_location_list (should_insert=0) at breakpoint.c:10539
#10 in delete_breakpoint (bpt=0x2f59290) at breakpoint.c:11392
#11 in bpfinishpy_out_of_scope (bpfinish_obj=0x7fdf3c9f8130) at ./python/py-finishbreakpoint.c:327
#12 in bpfinishpy_detect_out_scope_cb (b=0x2f59290, args=0x0) at ./python/py-finishbreakpoint.c:356
#13 in iterate_over_breakpoints (callback=0x65150d <bpfinishpy_detect_out_scope_cb>, data=0x0) at breakpoint.c:13385
#14 in bpfinishpy_handle_exit (inf=0x281d330) at ./python/py-finishbreakpoint.c:393
#15 in observer_inferior_exit_notification_stub (data=0x6516b1, args_data=0x7fff727e3740) at observer.inc:887
#16 in generic_observer_notify (subject=0x284f300, args=0x7fff727e3740) at observer.c:168
#17 in observer_notify_inferior_exit (inf=0x281d330) at observer.inc:912
#18 in exit_inferior_1 (inftoex=0x281d330, silent=1) at inferior.c:276
#19 in exit_inferior_silent (pid=42000) at inferior.c:305
#20 in discard_all_inferiors () at inferior.c:343
#21 in remote_close (quitting=0) at remote.c:2950
#22 in target_close (targ=0x1d19f80, quitting=0) at target.c:3387
#23 in unpush_target (t=0x1d19f80) at target.c:1024
#24 in remote_mourn_1 (target=0x1d19f80) at remote.c:7456
#25 in remote_mourn (ops=0x1d19f80) at remote.c:7449
#26 in target_mourn_inferior () at target.c:2747
#27 in handle_inferior_event (ecs=0x7fff727e3c30) at infrun.c:3408
#28 in wait_for_inferior () at infrun.c:2711
#29 in proceed (addr=18446744073709551615, siggnal=TARGET_SIGNAL_DEFAULT, step=0) at infrun.c:2276
#30 in continue_1 (all_threads=0) at infcmd.c:713
#31 in continue_command (args=0x0, from_tty=1) at infcmd.c:805


Reproducible with:
../gdbserver/gdbserver :1234 gdb.python/py-finish-breakpoint
gdb -nx -x ~/.gdbinit -ex r --args ../gdb -nx -ex 'file gdb.python/py-finish-breakpoint' -ex 'target remote localhost:1234' -ex 'b test_exec_exit' -ex c -ex 'source gdb.python/py-finish-breakpoint.py' -ex 'python SimpleFinishBreakpoint(gdb.newest_frame())' -ex c

I have seen this serial_debug_p crash in various GDB debugging cases but they
were not well reproducible.  I understand this bug is unrelated to
gdb.python/py-finish-breakpoint.exp .

I also tried to reorder remote_close a bit but this patch seems as the right
one to me.

The .exp patch fixes in fact an unrelated testcase but both happen with
gdbserver and py-finish-breakpoint.exp.

The testcase has been tested on x86_64-fedorarawhide-linux-gnu.


Thanks,
Jan


gdb/
2011-12-27  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* remote.c (remote_remove_breakpoint): Return 0 on NULL REMOTE_DESC.

gdb/testsuite/
2011-12-27  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* gdb.python/py-finish-breakpoint.exp (catch out of scope after exec):
	Make it unsupported with gdbserver.

--- a/gdb/remote.c
+++ b/gdb/remote.c
@@ -7734,6 +7734,13 @@ remote_remove_breakpoint (struct gdbarch *gdbarch,
   CORE_ADDR addr = bp_tgt->placed_address;
   struct remote_state *rs = get_remote_state ();
 
+  if (remote_desc == NULL)
+    {
+      /* remote_close is being executed as our caller.  Avoid error by
+	 reporting successful removal of the breakpoint.  */
+      return 0;
+    }
+
   if (remote_protocol_packets[PACKET_Z0].support != PACKET_DISABLE)
     {
       char *p = rs->buf;
--- a/gdb/testsuite/gdb.python/py-finish-breakpoint.exp
+++ b/gdb/testsuite/gdb.python/py-finish-breakpoint.exp
@@ -262,4 +262,17 @@ if ![runto "test_exec_exit"] then {
 
 gdb_test "python SimpleFinishBreakpoint(gdb.newest_frame())" "SimpleFinishBreakpoint init" "set FinishBP after the exec"
 gdb_test "catch exec" "Catchpoint.*\(exec\).*" "catch exec"
-gdb_test "continue" "SimpleFinishBreakpoint out of scope.*" "catch out of scope after exec"
+
+set test "catch out of scope after exec"
+gdb_test_multiple "continue" $test {
+    -re "warning: Error inserting catchpoint \[0-9\]+: Your system does not support this type\[ \r\n\]+of catchpoint\\.\r\n.*\r\n$gdb_prompt $" {
+	if [is_remote target] {
+	    unsupported $test
+	} else {
+	    fail $test
+	}
+    }
+    -re "SimpleFinishBreakpoint out of scope\r\n$gdb_prompt $" {
+	pass $test
+    }
+}