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2011-09-02 Pedro Alves <pedro@codesourcery.com> 

* linux-nat.c (in_pid_list_p): New.
	(linux_record_stopped_pid): Delete.
	(lin_lwp_attach_lwp): Check if PTRACE_ATTACH failed because we're
	already attached to the LWP.  Return an indication if so.
	(linux_nat_filter_event): Adjust.
	* linux-thread-db.c (attach_thread): Handle lin_lwp_attach_lwp
	returning an indication to ignore this thread.
This commit is contained in:
Pedro Alves 2011-09-02 21:03:06 +00:00
parent 68e77c9e30
commit 84636d2874
3 changed files with 86 additions and 14 deletions
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10
gdb/ChangeLog
View File

@ -1,3 +1,13 @@
2011-09-02 Pedro Alves <pedro@codesourcery.com>
* linux-nat.c (in_pid_list_p): New.
(linux_record_stopped_pid): Delete.
(lin_lwp_attach_lwp): Check if PTRACE_ATTACH failed because we're
already attached to the LWP. Return an indication if so.
(linux_nat_filter_event): Adjust.
* linux-thread-db.c (attach_thread): Handle lin_lwp_attach_lwp
returning an indication to ignore this thread.
2011-09-02 Pedro Alves <pedro@codesourcery.com>
* top.c: Include interps.h.

68
gdb/linux-nat.c
View File

@ -330,6 +330,17 @@ add_to_pid_list (struct simple_pid_list **listp, int pid, int status)
*listp = new_pid;
}
static int
in_pid_list_p (struct simple_pid_list *list, int pid)
{
struct simple_pid_list *p;
for (p = list; p != NULL; p = p->next)
if (p->pid == pid)
return 1;
return 0;
}
static int
pull_pid_from_list (struct simple_pid_list **listp, int pid, int *statusp)
{
@ -348,12 +359,6 @@ pull_pid_from_list (struct simple_pid_list **listp, int pid, int *statusp)
return 0;
}
static void
linux_record_stopped_pid (int pid, int status)
{
add_to_pid_list (&stopped_pids, pid, status);
}
/* A helper function for linux_test_for_tracefork, called after fork (). */
@ -1386,20 +1391,25 @@ linux_nat_post_attach_wait (ptid_t ptid, int first, int *cloned,
return status;
}
/* Attach to the LWP specified by PID. Return 0 if successful or -1
if the new LWP could not be attached. */
/* Attach to the LWP specified by PID. Return 0 if successful, -1 if
the new LWP could not be attached, or 1 if we're already auto
attached to this thread, but haven't processed the
PTRACE_EVENT_CLONE event of its parent thread, so we just ignore
its existance, without considering it an error. */
int
lin_lwp_attach_lwp (ptid_t ptid)
{
struct lwp_info *lp;
sigset_t prev_mask;
int lwpid;
gdb_assert (is_lwp (ptid));
block_child_signals (&prev_mask);
lp = find_lwp_pid (ptid);
lwpid = GET_LWP (ptid);
/* We assume that we're already attached to any LWP that has an id
equal to the overall process id, and to any LWP that is already
@ -1407,12 +1417,48 @@ lin_lwp_attach_lwp (ptid_t ptid)
and we've had PID wraparound since we last tried to stop all threads,
this assumption might be wrong; fortunately, this is very unlikely
to happen. */
if (GET_LWP (ptid) != GET_PID (ptid) && lp == NULL)
if (lwpid != GET_PID (ptid) && lp == NULL)
{
int status, cloned = 0, signalled = 0;
if (ptrace (PTRACE_ATTACH, GET_LWP (ptid), 0, 0) < 0)
if (ptrace (PTRACE_ATTACH, lwpid, 0, 0) < 0)
{
if (linux_supports_tracefork_flag)
{
/* If we haven't stopped all threads when we get here,
we may have seen a thread listed in thread_db's list,
but not processed the PTRACE_EVENT_CLONE yet. If
that's the case, ignore this new thread, and let
normal event handling discover it later. */
if (in_pid_list_p (stopped_pids, lwpid))
{
/* We've already seen this thread stop, but we
haven't seen the PTRACE_EVENT_CLONE extended
event yet. */
restore_child_signals_mask (&prev_mask);
return 0;
}
else
{
int new_pid;
int status;
/* See if we've got a stop for this new child
pending. If so, we're already attached. */
new_pid = my_waitpid (lwpid, &status, WNOHANG);
if (new_pid == -1 && errno == ECHILD)
new_pid = my_waitpid (lwpid, &status, __WCLONE | WNOHANG);
if (new_pid != -1)
{
if (WIFSTOPPED (status))
add_to_pid_list (&stopped_pids, lwpid, status);
restore_child_signals_mask (&prev_mask);
return 1;
}
}
}
/* If we fail to attach to the thread, issue a warning,
but continue. One way this can happen is if thread
creation is interrupted; as of Linux kernel 2.6.19, a
@ -3084,7 +3130,7 @@ linux_nat_filter_event (int lwpid, int status, int options)
from waitpid before or after the event is. */
if (WIFSTOPPED (status) && !lp)
{
linux_record_stopped_pid (lwpid, status);
add_to_pid_list (&stopped_pids, lwpid, status);
return NULL;
}

22
gdb/linux-thread-db.c
View File

@ -1140,9 +1140,25 @@ attach_thread (ptid_t ptid, const td_thrhandle_t *th_p,
/* Under GNU/Linux, we have to attach to each and every thread. */
if (target_has_execution
&& tp == NULL
&& lin_lwp_attach_lwp (BUILD_LWP (ti_p->ti_lid, GET_PID (ptid))) < 0)
return 0;
&& tp == NULL)
{
int res;
res = lin_lwp_attach_lwp (BUILD_LWP (ti_p->ti_lid, GET_PID (ptid)));
if (res < 0)
{
/* Error, stop iterating. */
return 0;
}
else if (res > 0)
{
/* Pretend this thread doesn't exist yet, and keep
iterating. */
return 1;
}
/* Otherwise, we sucessfully attached to the thread. */
}
/* Construct the thread's private data. */
private = xmalloc (sizeof (struct private_thread_info));