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* lin-lwp.c (count_events_callback): Fix formatting. Turn check 

commented with "paranoia" into gdb_assert.
(select_event_lwp_callback): Likewise.
(cancel_breakpoints_callback): Bail out early if LP is the event
LWP.  Add comment about backup up breakpoints.  Fix formatting and
debug message.
(select_event_lwp): Make solely repsonsible for switching event
LWP.  Fix formatting and remove bogus "ERROR" debug message.
Don't backup breakpoints from here.
(lin_lwp_wait): Don't touch LP->status, let select_event_lwp
handle that.  Only call select_event_lwp if we're not waiting for
a specific LWP, i.e. when PID == -1.  Backup breakpoints from here.
gdb_s390-2001-09-26-branch
Mark Kettenis 25 years ago
parent
32cfffe316
commit
00d4fce629
2 changed files with 87 additions and 68 deletions
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  1. 15
      gdb/ChangeLog
  2. 140
      gdb/lin-lwp.c

15
gdb/ChangeLog
View File

@ -1,3 +1,18 @@
2001-07-07 Mark Kettenis <kettenis@gnu.org>
* lin-lwp.c (count_events_callback): Fix formatting. Turn check
commented with "paranoia" into gdb_assert.
(select_event_lwp_callback): Likewise.
(cancel_breakpoints_callback): Bail out early if LP is the event
LWP. Add comment about backup up breakpoints. Fix formatting and
debug message.
(select_event_lwp): Make solely repsonsible for switching event
LWP. Fix formatting and remove bogus "ERROR" debug message.
Don't backup breakpoints from here.
(lin_lwp_wait): Don't touch LP->status, let select_event_lwp
handle that. Only call select_event_lwp if we're not waiting for
a specific LWP, i.e. when PID == -1. Backup breakpoints from here.
2001-07-06 Michael Snyder <msnyder@redhat.com>
* procfs.c (procfs_resume): Silence noisy warning.

140
gdb/lin-lwp.c
View File

@ -722,24 +722,24 @@ running_callback (struct lwp_info *lp, void *data)
return (lp->stopped == 0);
}
/* Count the LWP's that have had events. */
/* Count the LWP's that have had events. */
static int
count_events_callback (struct lwp_info *lp, void *data)
{
int *count = data;
/* Count only threads that have a SIGTRAP pending. */
if (lp->status != 0 &&
WIFSTOPPED (lp->status) &&
WSTOPSIG (lp->status) == SIGTRAP &&
count != NULL) /* paranoia */
gdb_assert (count != NULL);
/* Count only LWPs that have a SIGTRAP event pending. */
if (lp->status != 0
&& WIFSTOPPED (lp->status) && WSTOPSIG (lp->status) == SIGTRAP)
(*count)++;
return 0;
}
/* Select the LWP (if any) that is currently being single-stepped. */
/* Select the LWP (if any) that is currently being single-stepped. */
static int
select_singlestep_lwp_callback (struct lwp_info *lp, void *data)
@ -750,18 +750,18 @@ select_singlestep_lwp_callback (struct lwp_info *lp, void *data)
return 0;
}
/* Select the Nth LWP that has had a SIGTRAP event. */
/* Select the Nth LWP that has had a SIGTRAP event. */
static int
select_event_lwp_callback (struct lwp_info *lp, void *data)
{
int *selector = data;
/* Select only threads that have a SIGTRAP event pending. */
if (lp->status != 0 &&
WIFSTOPPED (lp->status) &&
WSTOPSIG (lp->status) == SIGTRAP &&
selector != NULL) /* paranoia */
gdb_assert (selector != NULL);
/* Select only LWPs that have a SIGTRAP event pending. */
if (lp->status != 0
&& WIFSTOPPED (lp->status) && WSTOPSIG (lp->status) == SIGTRAP)
if ((*selector)-- == 0)
return 1;
@ -773,32 +773,43 @@ cancel_breakpoints_callback (struct lwp_info *lp, void *data)
{
struct lwp_info *event_lp = data;
if (lp != event_lp &&
lp->status != 0 &&
WIFSTOPPED (lp->status) &&
WSTOPSIG (lp->status) == SIGTRAP &&
breakpoint_inserted_here_p (read_pc_pid (lp->ptid) -
DECR_PC_AFTER_BREAK))
/* Leave the LWP that has been elected to receive a SIGTRAP alone. */
if (lp == event_lp)
return 0;
/* If a LWP other than the LWP that we're reporting an event for has
hit a GDB breakpoint (as opposed to some random trap signal),
then just arrange for it to hit it again later. We don't keep
the SIGTRAP status and don't forward the SIGTRAP signal to the
LWP. We will handle the current event, eventually we will resume
all LWPs, and this one will get its breakpoint trap again.
If we do not do this, then we run the risk that the user will
delete or disable the breakpoint, but the LWP will have already
tripped on it. */
if (lp->status != 0
&& WIFSTOPPED (lp->status) && WSTOPSIG (lp->status) == SIGTRAP
&& breakpoint_inserted_here_p (read_pc_pid (lp->ptid) -
DECR_PC_AFTER_BREAK))
{
if (debug_lin_lwp)
{
fprintf_unfiltered (gdb_stdlog,
"Push back BP for %ld\n",
GET_LWP (lp->ptid));
}
/* For each lp except the event lp, if there was a trap,
set the PC to before the trap. */
fprintf_unfiltered (gdb_stdlog,
"Push back breakpoint for LWP %ld\n",
GET_LWP (lp->ptid));
/* Back up the PC if necessary. */
if (DECR_PC_AFTER_BREAK)
{
write_pc_pid (read_pc_pid (lp->ptid) - DECR_PC_AFTER_BREAK,
lp->ptid);
}
write_pc_pid (read_pc_pid (lp->ptid) - DECR_PC_AFTER_BREAK, lp->ptid);
/* Throw away the SIGTRAP. */
lp->status = 0;
}
return 0;
}
/* Select one LWP out of those that have events to be the event thread. */
/* Select one LWP out of those that have events pending. */
static void
select_event_lwp (struct lwp_info **orig_lp, int *status)
@ -807,54 +818,48 @@ select_event_lwp (struct lwp_info **orig_lp, int *status)
int random_selector;
struct lwp_info *event_lp;
/* Give preference to any LWP that is being single-stepped. */
/* Record the wait status for the origional LWP. */
(*orig_lp)->status = *status;
/* Give preference to any LWP that is being single-stepped. */
event_lp = iterate_over_lwps (select_singlestep_lwp_callback, NULL);
if (event_lp != NULL)
{
if (debug_lin_lwp)
fprintf_unfiltered (gdb_stdlog,
"Select singlestep lwp %ld\n",
fprintf_unfiltered (gdb_stdlog,
"Select single-step LWP %ld\n",
GET_LWP (event_lp->ptid));
}
else
{
/* No single-stepping LWP. Select one at random, out of those
which have had SIGTRAP events. */
which have had SIGTRAP events. */
/* First see how many SIGTRAP events we have. */
iterate_over_lwps (count_events_callback, (void *) &num_events);
/* First see how many SIGTRAP events we have. */
iterate_over_lwps (count_events_callback, &num_events);
/* OK, now randomly pick the Nth LWP of those that have had SIGTRAP. */
random_selector = (int)
/* Now randomly pick a LWP out of those that have had a SIGTRAP. */
random_selector = (int)
((num_events * (double) rand ()) / (RAND_MAX + 1.0));
if (debug_lin_lwp)
{
if (num_events > 1)
fprintf_unfiltered (gdb_stdlog,
"Found %d SIGTRAP events, selecting #%d\n",
num_events, random_selector);
else if (num_events <= 0)
fprintf_unfiltered (gdb_stdlog,
"ERROR select_event_lwp %d events!\n",
num_events);
}
if (debug_lin_lwp && num_events > 1)
fprintf_unfiltered (gdb_stdlog,
"Found %d SIGTRAP events, selecting #%d\n",
num_events, random_selector);
event_lp = iterate_over_lwps (select_event_lwp_callback,
(void *) &random_selector);
event_lp = iterate_over_lwps (select_event_lwp_callback,
&random_selector);
}
if (event_lp != NULL)
{
/* "event_lp" is now the selected event thread.
If any other threads have had SIGTRAP events, these events
must now be cancelled, so that the respective thread will
trip the breakpoint again once it is resumed. */
iterate_over_lwps (cancel_breakpoints_callback, (void *) event_lp);
/* Switch the event LWP. */
*orig_lp = event_lp;
*status = event_lp->status;
event_lp->status = 0;
}
/* Flush the wait status for the event LWP. */
(*orig_lp)->status = 0;
}
/* Return non-zero if LP has been resumed. */
@ -1097,12 +1102,6 @@ lin_lwp_wait (ptid_t ptid, struct target_waitstatus *ourstatus)
/* This LWP is stopped now. */
lp->stopped = 1;
if (WIFSTOPPED (status) && WSTOPSIG (status) == SIGTRAP)
{
/* Save SIGTRAP event for select_event_lwp. */
lp->status = status;
}
if (debug_lin_lwp)
fprintf_unfiltered (gdb_stdlog,
"LLW: Candidate event %d in %ld\n",
@ -1115,11 +1114,16 @@ lin_lwp_wait (ptid_t ptid, struct target_waitstatus *ourstatus)
longer running. */
iterate_over_lwps (stop_wait_callback, NULL);
/* MVS Now choose an event thread from among those that
have had events. Giving equal priority to all threads
that have had events helps prevent starvation. */
/* If we're not waiting for a specific LWP, choose an event LWP from
among those that have had events. Giving equal priority to all
LWPs that have had events helps prevent starvation. */
if (pid == -1)
select_event_lwp (&lp, &status);
select_event_lwp (&lp, &status);
/* Now that we've selected our final event LWP, cancel any
breakpoints in other LWPs that have hit a GDB breakpoint. See
the comment in cancel_breakpoints_callback to find out why. */
iterate_over_lwps (cancel_breakpoints_callback, lp);
/* If we're not running in "threaded" mode, we'll report the bare
process id. */

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