Re: [Patch] Mark the thread_event breakpoint as "not inserted" before calling thread_mourn_inferior

[Girish Shilamkar <girish at linsyssoft dot com>]

> You left out the interesting part of the trace; why is it fetching
> registers?  My GDB doesn't.  Presumably this is something specific to
> Red Hat's libthread_db.  Does td_thr_validate_p return TD_OK for a
> thread which is actually dead?
> 
	This is the stack trace td_thr_validate never returns , in fetch_regs
gdb calls perror_with_name (_("Couldn't get registers")); and control
never returns back to fetch_regs. 
----------------------------------------------------------------------
Program exited normally.

Breakpoint 1, fetch_regs (tid=-151132512) at ../../src/gdb/i386-linux-
nat.c:277
277           perror_with_name (_("Couldn't get registers"));
(gdb) bt
#0  fetch_regs (tid=-151132512) at ../../src/gdb/i386-linux-nat.c:277
#1  0x0808fdaf in i386_linux_fetch_inferior_registers (regno=-1)
    at ../../src/gdb/i386-linux-nat.c:513
#2  0x08091848 in thread_db_fetch_registers (regno=-1)
    at ../../src/gdb/linux-thread-db.c:1007
#3  0x0809058c in ps_lgetregs (ph=0xf6fde6a0, lwpid=29054,
gregset=0xfee6383c)
    at ../../src/gdb/proc-service.c:236
#4  0xf6db26b2 in td_ta_map_lwp2thr () from /lib/tls/libthread_db.so.1
#5  0xf6db3872 in td_thr_validate () from /lib/tls/libthread_db.so.1
#6  0x08091c1e in thread_db_thread_alive (ptid=
      {pid = 29054, lwp = 29061, tid = -193094736})
    at ../../src/gdb/linux-thread-db.c:1135
#7  0x080917b1 in thread_db_xfer_partial (ops=0x8280a80,
    object=TARGET_OBJECT_MEMORY, annex=0x0, readbuf=0x0,
    writebuf=0xfee639f0 "U\2174", offset=4626416, len=1)
    at ../../src/gdb/linux-thread-db.c:983
#8  0x0811267a in target_xfer_partial (ops=0x8280a80,
    object=TARGET_OBJECT_MEMORY, annex=0x0, readbuf=0x0,
writebuf=0xfee639f0,
    offset=4626416, len=1) at ../../src/gdb/target.c:864
#9  0x08112894 in xfer_using_stratum (object=TARGET_OBJECT_MEMORY,
annex=0x0,
    offset=4626416, len=Unhandled dwarf expression opcode 0x93


> 
> Try moving remove_thread_event_breakpoints below the call
> to target_beneath->to_mourn_inferior ().
> 
	It works , I have verified it on FC3 & FC4. I have attached the patch.

Thanks,
-Girish.

Index: src/gdb/linux-thread-db.c
===================================================================
--- gdb-cvs.orig/gdb/linux-thread-db.c	2006-01-23 14:20:23.331552656 +0530
+++ gdb-cvs/gdb/linux-thread-db.c	2006-01-23 14:25:29.955938664 +0530
@@ -1104,13 +1104,12 @@
 static void
 thread_db_mourn_inferior (void)
 {
-  remove_thread_event_breakpoints ();
-
   /* Forget about the child's process ID.  We shouldn't need it
      anymore.  */
   proc_handle.pid = 0;
 
   target_beneath->to_mourn_inferior ();
+  remove_thread_event_breakpoints ();
 
   /* Detach thread_db target ops.  */
   unpush_target (&thread_db_ops);