From 39383a48f726a69d632f4899acaccb0ba5f5a61b Mon Sep 17 00:00:00 2001 From: Joel Brobecker Date: Wed, 22 Sep 2010 22:50:54 +0000 Subject: [Ada] Do not compute task ptid when debugging core file After thread support over core files was added for GNU/Linux was added, we started noticing the following type of crash when trying to perform task switches (this is a bit accademic, since task switching is not supported when debugging core files - this is what our testcase was verifying). (please check out the comment inside ada-tasks.c:task_command for more details on this topic) The reason for the crash comes from the fact that the GNU/Linux thread layer now gets pushed on the target stack, causing the associated to_get_ada_task_ptid target method to be activated. This routine makes the assumption that, for all threads, the private area is not NULL. This is incorrect in the case of core files, as the core layer creates some threads with no private data. But, taking a step back, we don't need to try to compute the task ptid, as we'll never be using it anyways (we only use it for task switching). So the fix is to avoid the ptid computation altogether when debugging a core file. gdb/ChangeLog: * ada-tasks.c (read_atcb): Do not compute the task ptid when debugging a core file. --- gdb/ChangeLog | 5 +++++ gdb/ada-tasks.c | 15 ++++++++++++--- 2 files changed, 17 insertions(+), 3 deletions(-) (limited to 'gdb') diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 9f959c1..4b1b74e 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,8 @@ +2010-09-22 Joel Brobecker + + * ada-tasks.c (read_atcb): Do not compute the task ptid when + debugging a core file. + 2010-09-22 Jan Kratochvil Code cleanup. diff --git a/gdb/ada-tasks.c b/gdb/ada-tasks.c index f57f44f..8e42252 100644 --- a/gdb/ada-tasks.c +++ b/gdb/ada-tasks.c @@ -583,9 +583,18 @@ read_atcb (CORE_ADDR task_id, struct ada_task_info *task_info) } } - /* And finally, compute the task ptid. */ - - if (ada_task_is_alive (task_info)) + /* And finally, compute the task ptid. Note that there are situations + where this cannot be determined: + - The task is no longer alive - the ptid is irrelevant; + - We are debugging a core file - the thread is not always + completely preserved for us to link back a task to its + underlying thread. Since we do not support task switching + when debugging core files anyway, we don't need to compute + that task ptid. + In either case, we don't need that ptid, and it is just good enough + to set it to null_ptid. */ + + if (target_has_execution && ada_task_is_alive (task_info)) task_info->ptid = ptid_from_atcb_common (common_value); else task_info->ptid = null_ptid; -- cgit v1.1