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Fix attaching to cloned processes. This fixes PR gdb/61. 

* lin-lwp.c (struct lwp_info): Add new member `cloned'.
(is_cloned) Removed.
(lin_lwp_attach_lwp): Don't call stop_wait_callback.  Instead call
waitpid explicitly.  Mark the LWP as cloned if waitpid fails and
retry with __WCLONE flag.
(lin_lwp_attach): Likewise.  Warn if attaching to a cloned process.
(detach_callback): Replace use of is_cloned with explicit check on
LWP id and process id.
(stop_wait_callback): Replace use of is_cloned with check if LWP
is marked as cloned.
[CHILD_WAIT] (child_wait): New function.
(lin_lwp_wait): Replace use of is_cloned with check if LWP is
marked as cloned.  Mark newly detected LWPs as cloned if detected
by waitpid with __WCLONE flag.
(kill_wait_callback): Replace use of is_cloned with check if LWP
is marked as cloned.
* config/i386/nm-linux.h (struct target_waitstatus): Add forward
declaration.
(child_wait): Add prototype.
(CHILD_WAIT): Define.
This commit is contained in:
Mark Kettenis 2001-10-14 11:30:37 +00:00
parent 9fa87a061b
commit cacab7c477
3 changed files with 132 additions and 19 deletions
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24
gdb/ChangeLog
View File

@ -1,3 +1,27 @@
2001-10-14 Mark Kettenis <kettenis@gnu.org>
Fix attaching to cloned processes. This fixes PR gdb/61.
* lin-lwp.c (struct lwp_info): Add new member `cloned'.
(is_cloned) Removed.
(lin_lwp_attach_lwp): Don't call stop_wait_callback. Instead call
waitpid explicitly. Mark the LWP as cloned if waitpid fails and
retry with __WCLONE flag.
(lin_lwp_attach): Likewise. Warn if attaching to a cloned process.
(detach_callback): Replace use of is_cloned with explicit check on
LWP id and process id.
(stop_wait_callback): Replace use of is_cloned with check if LWP
is marked as cloned.
[CHILD_WAIT] (child_wait): New function.
(lin_lwp_wait): Replace use of is_cloned with check if LWP is
marked as cloned. Mark newly detected LWPs as cloned if detected
by waitpid with __WCLONE flag.
(kill_wait_callback): Replace use of is_cloned with check if LWP
is marked as cloned.
* config/i386/nm-linux.h (struct target_waitstatus): Add forward
declaration.
(child_wait): Add prototype.
(CHILD_WAIT): Define.
2001-10-13 Andrew Cagney <ac131313@redhat.com>
S/390 31 & 64 bit target and GNU/Linux native support.

5
gdb/config/i386/nm-linux.h
View File

@ -87,6 +87,11 @@ extern int cannot_store_register (int regno);
/* Override child_resume in `infptrace.c'. */
#define CHILD_RESUME
/* Override child_wait in `inftarg.c'. */
struct target_waitstatus;
extern ptid_t child_wait (ptid_t ptid, struct target_waitstatus *ourstatus);
#define CHILD_WAIT
/* FIXME: kettenis/2000-09-03: This should be moved to ../nm-linux.h
once we have converted all Linux targets to use the new threads
stuff (without the #undef of course). */

122
gdb/lin-lwp.c
View File

@ -75,6 +75,11 @@ struct lwp_info
and overall process id. */
ptid_t ptid;
/* Non-zero if this LWP is cloned. In this context "cloned" means
that the LWP is reporting to its parent using a signal other than
SIGCHLD. */
int cloned;
/* Non-zero if we sent this LWP a SIGSTOP (but the LWP didn't report
it back yet). */
int signalled;
@ -115,8 +120,6 @@ static int threaded;
#define is_lwp(ptid) (GET_LWP (ptid) != 0)
#define BUILD_LWP(lwp, pid) ptid_build (pid, lwp, 0)
#define is_cloned(pid) (GET_LWP (pid) != GET_PID (pid))
/* If the last reported event was a SIGTRAP, this variable is set to
the process id of the LWP/thread that got it. */
ptid_t trap_ptid;
@ -352,18 +355,33 @@ lin_lwp_attach_lwp (ptid_t ptid, int verbose)
if (verbose)
printf_filtered ("[New %s]\n", target_pid_to_str (ptid));
/* We assume that we're already tracing the initial process. */
if (is_cloned (ptid) && ptrace (PTRACE_ATTACH, GET_LWP (ptid), 0, 0) < 0)
error ("Can't attach %s: %s", target_pid_to_str (ptid), strerror (errno));
lp = find_lwp_pid (ptid);
if (lp == NULL)
lp = add_lwp (ptid);
if (is_cloned (ptid))
/* We assume that we're already attached to any LWP that has an
id equal to the overall process id. */
if (GET_LWP (ptid) != GET_PID (ptid))
{
lp->signalled = 1;
stop_wait_callback (lp, NULL);
pid_t pid;
int status;
if (ptrace (PTRACE_ATTACH, GET_LWP (ptid), 0, 0) < 0)
error ("Can't attach %s: %s", target_pid_to_str (ptid),
strerror (errno));
pid = waitpid (GET_LWP (ptid), &status, 0);
if (pid == -1 && errno == ECHILD)
{
/* Try again with __WCLONE to check cloned processes. */
pid = waitpid (GET_LWP (ptid), &status, __WCLONE);
lp->cloned = 1;
}
gdb_assert (pid == GET_LWP (ptid)
&& WIFSTOPPED (status) && WSTOPSIG (status));
lp->stopped = 1;
}
}
@ -371,20 +389,33 @@ static void
lin_lwp_attach (char *args, int from_tty)
{
struct lwp_info *lp;
pid_t pid;
int status;
/* FIXME: We should probably accept a list of process id's, and
attach all of them. */
child_ops.to_attach (args, from_tty);
/* Add the initial process as the first LWP to the list. */
lp = add_lwp (BUILD_LWP (PIDGET (inferior_ptid), PIDGET (inferior_ptid)));
lp = add_lwp (BUILD_LWP (GET_PID (inferior_ptid), GET_PID (inferior_ptid)));
/* Make sure the initial process is stopped. The user-level threads
layer might want to poke around in the inferior, and that won't
work if things haven't stabilized yet. */
lp->signalled = 1;
stop_wait_callback (lp, NULL);
gdb_assert (lp->status == 0);
pid = waitpid (GET_PID (inferior_ptid), &status, 0);
if (pid == -1 && errno == ECHILD)
{
warning ("%s is a cloned process", target_pid_to_str (inferior_ptid));
/* Try again with __WCLONE to check cloned processes. */
pid = waitpid (GET_PID (inferior_ptid), &status, __WCLONE);
lp->cloned = 1;
}
gdb_assert (pid == GET_PID (inferior_ptid)
&& WIFSTOPPED (status) && WSTOPSIG (status) == SIGSTOP);
lp->stopped = 1;
/* Fake the SIGSTOP that core GDB expects. */
lp->status = W_STOPCODE (SIGSTOP);
@ -415,7 +446,9 @@ detach_callback (struct lwp_info *lp, void *data)
gdb_assert (lp->status == 0 || WIFSTOPPED (lp->status));
}
if (is_cloned (lp->ptid))
/* We don't actually detach from the LWP that has an id equal to the
overall process id just yet. */
if (GET_LWP (lp->ptid) != GET_PID (lp->ptid))
{
if (ptrace (PTRACE_DETACH, GET_LWP (lp->ptid), 0,
WSTOPSIG (lp->status)) < 0)
@ -433,7 +466,7 @@ lin_lwp_detach (char *args, int from_tty)
{
iterate_over_lwps (detach_callback, NULL);
/* Only the initial (uncloned) process should be left right now. */
/* Only the initial process should be left right now. */
gdb_assert (num_lwps == 1);
trap_ptid = null_ptid;
@ -610,8 +643,7 @@ stop_wait_callback (struct lwp_info *lp, void *data)
gdb_assert (lp->status == 0);
pid = waitpid (GET_LWP (lp->ptid), &status,
is_cloned (lp->ptid) ? __WCLONE : 0);
pid = waitpid (GET_LWP (lp->ptid), &status, lp->cloned ? __WCLONE : 0);
if (pid == -1 && errno == ECHILD)
/* OK, the proccess has disappeared. We'll catch the actual
exit event in lin_lwp_wait. */
@ -888,6 +920,55 @@ resumed_callback (struct lwp_info *lp, void *data)
return lp->resumed;
}
#ifdef CHILD_WAIT
/* We need to override child_wait to support attaching to cloned
processes, since a normal wait (as done by the default version)
ignores those processes. */
/* Wait for child PTID to do something. Return id of the child,
minus_one_ptid in case of error; store status into *OURSTATUS. */
ptid_t
child_wait (ptid_t ptid, struct target_waitstatus *ourstatus)
{
int save_errno;
int status;
pid_t pid;
do
{
set_sigint_trap (); /* Causes SIGINT to be passed on to the
attached process. */
set_sigio_trap ();
pid = waitpid (GET_PID (ptid), &status, 0);
if (pid == -1 && errno == ECHILD)
/* Try again with __WCLONE to check cloned processes. */
pid = waitpid (GET_PID (ptid), &status, __WCLONE);
save_errno = errno;
clear_sigio_trap ();
clear_sigint_trap ();
}
while (pid == -1 && errno == EINTR);
if (pid == -1)
{
warning ("Child process unexpectedly missing: %s", strerror (errno));
/* Claim it exited with unknown signal. */
ourstatus->kind = TARGET_WAITKIND_SIGNALLED;
ourstatus->value.sig = TARGET_SIGNAL_UNKNOWN;
return minus_one_ptid;
}
store_waitstatus (ourstatus, status);
return pid_to_ptid (pid);
}
#endif
static ptid_t
lin_lwp_wait (ptid_t ptid, struct target_waitstatus *ourstatus)
{
@ -954,7 +1035,7 @@ lin_lwp_wait (ptid_t ptid, struct target_waitstatus *ourstatus)
/* If we have to wait, take into account whether PID is a cloned
process or not. And we have to convert it to something that
the layer beneath us can understand. */
options = is_cloned (lp->ptid) ? __WCLONE : 0;
options = lp->cloned ? __WCLONE : 0;
pid = GET_LWP (ptid);
}
@ -997,6 +1078,9 @@ lin_lwp_wait (ptid_t ptid, struct target_waitstatus *ourstatus)
if (! lp)
{
lp = add_lwp (BUILD_LWP (lwpid, GET_PID (inferior_ptid)));
if (options & __WCLONE)
lp->cloned = 1;
if (threaded)
{
gdb_assert (WIFSTOPPED (status)
@ -1189,7 +1273,7 @@ kill_wait_callback (struct lwp_info *lp, void *data)
/* For cloned processes we must check both with __WCLONE and
without, since the exit status of a cloned process isn't reported
with __WCLONE. */
if (is_cloned (lp->ptid))
if (lp->cloned)
{
do
{