http://sourceware.org/ml/gdb-patches/2011-02/msg00680.html

Subject: [patch 2/3] Fix threading internal error on corrupted memory [rediff]

[rediff]

gdb/

2011-02-24  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* linux-thread-db.c (find_new_threads_callback): Exit on zero TI_TID

	even if !TARGET_HAS_EXECUTION.

gdb/testsuite/

2011-02-24  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* gdb.threads/gcore-thread.exp ($core0file): New variable.

	(clear __stack_user.next, clear stack_used.next)

	(save a zeroed-threads corefile): New test.

	Call core_load for $core0file.

	(zeroed-threads cannot be listed): New test.

--- a/gdb/linux-thread-db.c

+++ b/gdb/linux-thread-db.c

@@ -1335,7 +1335,7 @@ find_new_threads_callback (const td_thrhandle_t *th_p, void *data)

   if (ti.ti_state == TD_THR_UNKNOWN || ti.ti_state == TD_THR_ZOMBIE)

     return 0;			/* A zombie -- ignore.  */

-  if (ti.ti_tid == 0 && target_has_execution)

+  if (ti.ti_tid == 0)

     {

       /* A thread ID of zero means that this is the main thread, but

 	 glibc has not yet initialized thread-local storage and the

@@ -1347,10 +1347,13 @@ find_new_threads_callback (const td_thrhandle_t *th_p, void *data)

 	 need this glibc bug workaround.  */

       info->need_stale_parent_threads_check = 0;

-      err = info->td_thr_event_enable_p (th_p, 1);

-      if (err != TD_OK)

-	error (_("Cannot enable thread event reporting for LWP %d: %s"),

-	       (int) ti.ti_lid, thread_db_err_str (err));

+      if (target_has_execution)

+	{

+	  err = info->td_thr_event_enable_p (th_p, 1);

+	  if (err != TD_OK)

+	    error (_("Cannot enable thread event reporting for LWP %d: %s"),

+		   (int) ti.ti_lid, thread_db_err_str (err));

+	}

       return 0;

     }

--- a/gdb/testsuite/gdb.threads/gcore-thread.exp

+++ b/gdb/testsuite/gdb.threads/gcore-thread.exp

@@ -26,6 +26,7 @@ set testfile "gcore-thread"

 set srcfile  pthreads.c

 set binfile  ${objdir}/${subdir}/${testfile}

 set corefile ${objdir}/${subdir}/${testfile}.test

+set core0file ${objdir}/${subdir}/${testfile}0.test

 if [istarget "*-*-linux"] then {

     set target_cflags "-D_MIT_POSIX_THREADS"

@@ -110,6 +111,29 @@ if {!$core_supported} {

 }

+# Test the uninitialized thread list.

+# Provide the case of glibc td_thr_get_info handling of:

+# /* Special case for the main thread before initialization.  */

+

+foreach symbol {__stack_user stack_used} {

+    set test "clear ${symbol}.next"

+    gdb_test_multiple "p *(void **) &${symbol} = 0" $test {

+	-re " = \\(void \\*\\) 0x0\r\n$gdb_prompt $" {

+	    pass $test

+	}

+	-re "No symbol \"${symbol}\" in current context\\.\r\n$gdb_prompt $" {

+	    xfail $test

+	    # Do not do the verification.

+	    set core0file ""

+	}

+    }

+}

+

+if {"$core0file" != ""} {

+    gdb_test "gcore $core0file" "Saved corefile .*" "save a zeroed-threads corefile"

+}

+

+

 # Now restart gdb and load the corefile.

 clean_restart ${testfile}

@@ -160,3 +184,11 @@ gdb_test "info threads" ".* thread2 .*" \

 gdb_test "info threads" ".*${nl}\\* ${horiz} thread2 .*" \

 	"thread2 is current thread in corefile"

+

+

+# Test the uninitialized thread list.

+

+if {"$core0file" != "" && [load_core $core0file]} {

+

+    gdb_test "info threads" "Cannot find new threads: .*" "zeroed-threads cannot be listed"

+}