Re: linux native async mode support

Pedro Alves
2008-03-21T17:19:59Z

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A Friday 21 March 2008 15:54:37, Daniel Jacobowitz wrote:
>
> This is OK to commit now. I'm sure we'll shake some more bugs out of
> it in the next few weeks :-)

Thanks! I'm sure we will. :-)

This is what I checked in after another round of testing
on x86_64-unknown-linux-gnu.

--
Pedro Alves

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Index: ChangeLog
===================================================================
RCS file: /cvs/src/src/gdb/ChangeLog,v
retrieving revision 1.9241
diff -u -p -r1.9241 ChangeLog
--- ChangeLog 21 Mar 2008 15:44:53 -0000 1.9241
+++ ChangeLog 21 Mar 2008 17:05:49 -0000
@@ -1,3 +1,105 @@
+2008-03-21 Pedro Alves <pedro@codesourcery.com>
+
+ Linux native async support.
+
+ * target.h (struct target_ops): Delete to_async_mask_value and add
+ to_async_mask.
+ (target_is_async_p, target_async): Formatting.
+ (target_async_mask_value): Delete.
+ (target_async_mask): Delete function declaration, and add new
+ target macro with the same name.
+
+ * target.c (update_current_target): Replace to_async_mask_value by
+ to_async_mask. Default to_async_mask to return_one.
+ (target_async_mask): Delete.
+ (find_default_can_async_p, find_default_is_async_p): New.
+ (init_dummy_target): register find_default_can_async_p and
+ find_default_is_async_p on the dummy target.
+
+ * linux-nat.c: Include inf-loop.h, event-loop.h and event-top.h.
+ (debug_linux_nat_async): New global.
+ (show_debug_linux_nat_async): New function.
+ (linux_nat_async_enabled, linux_nat_async_mask_value)
+ (linux_nat_event_pipe, linux_nat_num_queued_events)
+ (linux_nat_async_events_enabled): New globals.
+ (struct waitpid_result): New struct.
+ (waitpid_queue): New global.
+ (queued_waitpid, push_waitpid, drain_queued_events): New.
+ (my_waitpid): Call queued_waitpid.
+ (linux_child_follow_fork): Disable async events during the call.
+ (blocked_mask): Delete.
+ (sync_sigchld_action, async_sigchld_action): New globals.
+ (lin_lwp_attach_lwp): In sync mode, don't reblock SIGCHLD. In
+ async mode, block events during the call.
+ (linux_nat_create_inferior): New.
+ (linux_nat_attach): In sync mode, restore the mask states. In
+ async mode, wake the event loop immediatelly.
+ (detach_callback): Drain all queued events of the lwp we're
+ detaching from.
+ (linux_nat_detach): Block async mode, and drain events of the main
+ process.
+ (linux_nat_resume): If in async mode, mask async events during the
+ call. If short circuiting, force event loop to wake up. If
+ resuming, set target_executing, and register target events in the
+ event loop.
+ (pipe_to_local_event_queue, local_event_queue_to_pipe): New.
+ (linux_nat_wait): In async mode, block events during the call.
+ Only enable/disable passing SIGINT to the inferior in sync mode.
+ Get events from local waitpid queue. If no interesting events was
+ found, return to events loop. Reregister target events in the
+ event loop on exit. In sync mode, no need to reblock SIGCHLD.
+ (linux_nat_kill): Disable events on entry.
+ (linux_nat_mourn_inferior): In sync mode, don't restore the masks
+ here. Detach async mode from the event loop if there are no more
+ forks available, otherwise leave it on.
+ (sigchld_handler): Assure this is called only in sync mode.
+ (linux_async_permitted, linux_async_permitted_1): New globals.
+ (set_maintenance_linux_async_permitted)
+ (show_maintenance_linux_async_permitted): New functions.
+ (linux_nat_is_async_p, linux_nat_can_async_p)
+ (linux_nat_async_mask): New.
+ (linux_nat_event_pipe_pop, linux_nat_event_pipe_push): New.
+ (get_pending_events, async_sigchld_handler): New.
+ (linux_nat_async_events): New.
+ (async_terminal_is_ours): New global.
+ (linux_nat_terminal_inferior, linux_nat_terminal_ours): New.
+ (async_client_callback, async_client_context): New.
+ (linux_nat_async_file_handler, linux_nat_async)
+ (linux_nat_disable_async, linux_nat_enable_async): New.
+ (linux_nat_add_target): Register linux_nat_create_inferior,
+ linux_nat_can_async_p, linux_nat_is_async_p, linux_nat_async,
+ linux_nat_async_mask, linux_nat_terminal_inferior and
+ linux_nat_terminal_ours.
+ (_initialize_linux_nat): Remove local action variable, and update
+ code that used it to use sync_sigchld_action. Add new
+ "lin-lwp-async" debug set/show command. Put the "lin-lwp" debug
+ set/show command in the maintenance class. Add new "linux-async"
+ maintenance set/show command. Block SIGCHLD by default. Setup
+ async_sichld_action, and sync_sigchld_action. Install the default
+ async mode.
+ (lin_thread_get_thread_signals): Use a local sigset_t for blocking
+ the cancel signals.
+
+ * linux-thread-db.c (re_check_for_thread_db): New.
+ (clear_lwpid_callback): Handle TARGET_WAITKIND_IGNORE.
+ (thread_db_can_async_p, thread_db_is_async_p, thread_db_async)
+ (thread_db_async_mask): New.
+ (init_thread_db_ops): Register thread_db_can_async_p,
+ thread_db_is_async_p, thread_db_async and thread_db_async_mask.
+
+ * remote.c (remote_async_mask_value): New.
+ (remote_return_zero): New.
+ (init_remote_ops): Register remote_return_zero as callbacks of
+ to_can_async_p and to_is_async_p.
+ (remote_can_async_p, remote_is_async_p, remote_async): Update to
+ use remote_async_mask_value.
+ (remote_async_mask): New.
+ (init_remote_async_ops): Remove to_async_mask_value setting and
+ register remote_async_mask as to_async_mask callback in
+ remote_async_ops.
+
+ * Makefile.in (linux-nat.o): Update.
+
2008-03-21 Daniel Jacobowitz <dan@codesourcery.com>

* gdbthread.h (add_thread_with_info): New.
Index: target.h
===================================================================
RCS file: /cvs/src/src/gdb/target.h,v
retrieving revision 1.113
diff -u -p -r1.113 target.h
--- target.h 15 Mar 2008 14:55:21 -0000 1.113
+++ target.h 21 Mar 2008 17:05:49 -0000
@@ -414,9 +414,8 @@ struct target_ops
/* ASYNC target controls */
int (*to_can_async_p) (void);
int (*to_is_async_p) (void);
- void (*to_async) (void (*cb) (enum inferior_event_type, void *context),
- void *context);
- int to_async_mask_value;
+ void (*to_async) (void (*) (enum inferior_event_type, void *), void *);
+ int (*to_async_mask) (int);
int (*to_find_memory_regions) (int (*) (CORE_ADDR,
unsigned long,
int, int, int,
@@ -938,11 +937,11 @@ int target_follow_fork (int follow_child
#define target_can_async_p() (current_target.to_can_async_p ())

/* Is the target in asynchronous execution mode? */
-#define target_is_async_p() (current_target.to_is_async_p())
+#define target_is_async_p() (current_target.to_is_async_p ())

/* Put the target in async mode with the specified callback function. */
#define target_async(CALLBACK,CONTEXT) \
- (current_target.to_async((CALLBACK), (CONTEXT)))
+ (current_target.to_async ((CALLBACK), (CONTEXT)))

/* This is to be used ONLY within call_function_by_hand(). It provides
a workaround, to have inferior function calls done in sychronous
@@ -958,10 +957,8 @@ int target_follow_fork (int follow_child
the turning async on and off to the single execution commands,
from where it is done currently, in remote_resume(). */

-#define target_async_mask_value \
- (current_target.to_async_mask_value)
-
-extern int target_async_mask (int mask);
+#define target_async_mask(MASK) \
+ (current_target.to_async_mask (MASK))

/* Converts a process id to a string. Usually, the string just contains
`process xyz', but on some systems it may contain
Index: target.c
===================================================================
RCS file: /cvs/src/src/gdb/target.c,v
retrieving revision 1.157
diff -u -p -r1.157 target.c
--- target.c 15 Mar 2008 14:55:21 -0000 1.157
+++ target.c 21 Mar 2008 17:05:49 -0000
@@ -464,7 +464,7 @@ update_current_target (void)
INHERIT (to_can_async_p, t);
INHERIT (to_is_async_p, t);
INHERIT (to_async, t);
- INHERIT (to_async_mask_value, t);
+ INHERIT (to_async_mask, t);
INHERIT (to_find_memory_regions, t);
INHERIT (to_make_corefile_notes, t);
INHERIT (to_get_thread_local_address, t);
@@ -637,6 +637,9 @@ update_current_target (void)
de_fault (to_async,
(void (*) (void (*) (enum inferior_event_type, void*), void*))
tcomplain);
+ de_fault (to_async_mask,
+ (int (*) (int))
+ return_one);
current_target.to_read_description = NULL;
#undef de_fault

@@ -1694,14 +1697,6 @@ target_disconnect (char *args, int from_
tcomplain ();
}

-int
-target_async_mask (int mask)
-{
- int saved_async_masked_status = target_async_mask_value;
- target_async_mask_value = mask;
- return saved_async_masked_status;
-}
-
/* Look through the list of possible targets for a target that can
follow forks. */

@@ -1835,6 +1830,28 @@ find_default_create_inferior (char *exec
return;
}

+int
+find_default_can_async_p (void)
+{
+ struct target_ops *t;
+
+ t = find_default_run_target ("async");
+ if (t->to_can_async_p)
+ return (t->to_can_async_p) ();
+ return 0;
+}
+
+int
+find_default_is_async_p (void)
+{
+ struct target_ops *t;
+
+ t = find_default_run_target ("async");
+ if (t->to_is_async_p)
+ return (t->to_is_async_p) ();
+ return 0;
+}
+
static int
default_region_ok_for_hw_watchpoint (CORE_ADDR addr, int len)
{
@@ -2099,6 +2116,8 @@ init_dummy_target (void)
dummy_target.to_doc = "";
dummy_target.to_attach = find_default_attach;
dummy_target.to_create_inferior = find_default_create_inferior;
+ dummy_target.to_can_async_p = find_default_can_async_p;
+ dummy_target.to_is_async_p = find_default_is_async_p;
dummy_target.to_pid_to_str = normal_pid_to_str;
dummy_target.to_stratum = dummy_stratum;
dummy_target.to_find_memory_regions = dummy_find_memory_regions;
Index: linux-nat.c
===================================================================
RCS file: /cvs/src/src/gdb/linux-nat.c,v
retrieving revision 1.77
diff -u -p -r1.77 linux-nat.c
--- linux-nat.c 21 Mar 2008 15:44:53 -0000 1.77
+++ linux-nat.c 21 Mar 2008 17:05:52 -0000
@@ -46,6 +46,9 @@
#include "gdbthread.h" /* for struct thread_info etc. */
#include "gdb_stat.h" /* for struct stat */
#include <fcntl.h> /* for O_RDONLY */
+#include "inf-loop.h"
+#include "event-loop.h"
+#include "event-top.h"

#ifndef O_LARGEFILE
#define O_LARGEFILE 0
@@ -113,6 +116,15 @@ show_debug_linux_nat (struct ui_file *fi
value);
}

+static int debug_linux_nat_async = 0;
+static void
+show_debug_linux_nat_async (struct ui_file *file, int from_tty,
+ struct cmd_list_element *c, const char *value)
+{
+ fprintf_filtered (file, _("Debugging of GNU/Linux async lwp module is %s.\n"),
+ value);
+}
+
static int linux_parent_pid;

struct simple_pid_list
@@ -133,6 +145,158 @@ static int linux_supports_tracefork_flag

static int linux_supports_tracevforkdone_flag = -1;

+/* Async mode support */
+
+/* To listen to target events asynchronously, we install a SIGCHLD
+ handler whose duty is to call waitpid (-1, ..., WNOHANG) to get all
+ the pending events into a pipe. Whenever we're ready to handle
+ events asynchronously, this pipe is registered as the waitable file
+ handle in the event loop. When we get to entry target points
+ coming out of the common code (target_wait, target_resume, ...),
+ that are going to call waitpid, we block SIGCHLD signals, and
+ remove all the events placed in the pipe into a local queue. All
+ the subsequent calls to my_waitpid (a waitpid wrapper) check this
+ local queue first. */
+
+/* True if async mode is currently on. */
+static int linux_nat_async_enabled;
+
+/* Zero if the async mode, although enabled, is masked, which means
+ linux_nat_wait should behave as if async mode was off. */
+static int linux_nat_async_mask_value = 1;
+
+/* The read/write ends of the pipe registered as waitable file in the
+ event loop. */
+static int linux_nat_event_pipe[2] = { -1, -1 };
+
+/* Number of queued events in the pipe. */
+static volatile int linux_nat_num_queued_events;
+
+/* If async mode is on, true if we're listening for events; false if
+ target events are blocked. */
+static int linux_nat_async_events_enabled;
+
+static int linux_nat_async_events (int enable);
+static void pipe_to_local_event_queue (void);
+static void local_event_queue_to_pipe (void);
+static void linux_nat_event_pipe_push (int pid, int status, int options);
+static int linux_nat_event_pipe_pop (int* ptr_status, int* ptr_options);
+static void linux_nat_set_async_mode (int on);
+static void linux_nat_async (void (*callback)
+ (enum inferior_event_type event_type, void *context),
+ void *context);
+static int linux_nat_async_mask (int mask);
+
+/* Captures the result of a successful waitpid call, along with the
+ options used in that call. */
+struct waitpid_result
+{
+ int pid;
+ int status;
+ int options;
+ struct waitpid_result *next;
+};
+
+/* A singly-linked list of the results of the waitpid calls performed
+ in the async SIGCHLD handler. */
+static struct waitpid_result *waitpid_queue = NULL;
+
+static int
+queued_waitpid (int pid, int *status, int flags)
+{
+ struct waitpid_result *msg = waitpid_queue, *prev = NULL;
+
+ if (debug_linux_nat_async)
+ fprintf_unfiltered (gdb_stdlog,
+ "\
+QWPID: linux_nat_async_events_enabled(%d), linux_nat_num_queued_events(%d)\n",
+ linux_nat_async_events_enabled,
+ linux_nat_num_queued_events);
+
+ if (flags & __WALL)
+ {
+ for (; msg; prev = msg, msg = msg->next)
+ if (pid == -1 || pid == msg->pid)
+ break;
+ }
+ else if (flags & __WCLONE)
+ {
+ for (; msg; prev = msg, msg = msg->next)
+ if (msg->options & __WCLONE
+ && (pid == -1 || pid == msg->pid))
+ break;
+ }
+ else
+ {
+ for (; msg; prev = msg, msg = msg->next)
+ if ((msg->options & __WCLONE) == 0
+ && (pid == -1 || pid == msg->pid))
+ break;
+ }
+
+ if (msg)
+ {
+ int pid;
+
+ if (prev)
+ prev->next = msg->next;
+ else
+ waitpid_queue = msg->next;
+
+ msg->next = NULL;
+ if (status)
+ *status = msg->status;
+ pid = msg->pid;
+
+ if (debug_linux_nat_async)
+ fprintf_unfiltered (gdb_stdlog, "QWPID: pid(%d), status(%x)\n",
+ pid, msg->status);
+ xfree (msg);
+
+ return pid;
+ }
+
+ if (debug_linux_nat_async)
+ fprintf_unfiltered (gdb_stdlog, "QWPID: miss\n");
+
+ if (status)
+ *status = 0;
+ return -1;
+}
+
+static void
+push_waitpid (int pid, int status, int options)
+{
+ struct waitpid_result *event, *new_event;
+
+ new_event = xmalloc (sizeof (*new_event));
+ new_event->pid = pid;
+ new_event->status = status;
+ new_event->options = options;
+ new_event->next = NULL;
+
+ if (waitpid_queue)
+ {
+ for (event = waitpid_queue;
+ event && event->next;
+ event = event->next)
+ ;
+
+ event->next = new_event;
+ }
+ else
+ waitpid_queue = new_event;
+}
+
+/* Drain all queued event of PID. If PID is -1, the effect is of
+ draining all events. */
+static void
+drain_queued_events (int pid)
+{
+ while (queued_waitpid (pid, NULL, __WALL) != -1)
+ ;
+}
+
\f
/* Trivial list manipulation functions to keep track of a list of
new stopped processes. */
@@ -183,12 +347,21 @@ linux_tracefork_child (void)
_exit (0);
}

-/* Wrapper function for waitpid which handles EINTR. */
+/* Wrapper function for waitpid which handles EINTR, and checks for
+ locally queued events. */

static int
my_waitpid (int pid, int *status, int flags)
{
int ret;
+
+ /* There should be no concurrent calls to waitpid. */
+ gdb_assert (!linux_nat_async_events_enabled);
+
+ ret = queued_waitpid (pid, status, flags);
+ if (ret != -1)
+ return ret;
+
do
{
ret = waitpid (pid, status, flags);
@@ -362,6 +535,9 @@ linux_child_follow_fork (struct target_o
int has_vforked;
int parent_pid, child_pid;

+ if (target_can_async_p ())
+ target_async (NULL, 0);
+
get_last_target_status (&last_ptid, &last_status);
has_vforked = (last_status.kind == TARGET_WAITKIND_VFORKED);
parent_pid = ptid_get_lwp (last_ptid);
@@ -506,9 +682,7 @@ linux_child_follow_fork (struct target_o
fork_save_infrun_state (fp, 0);
}
else
- {
- target_detach (NULL, 0);
- }
+ target_detach (NULL, 0);

inferior_ptid = ptid_build (child_pid, child_pid, 0);

@@ -523,6 +697,9 @@ linux_child_follow_fork (struct target_o
follow_inferior_reset_breakpoints ();
}

+ if (target_can_async_p ())
+ target_async (inferior_event_handler, 0);
+
return 0;
}

@@ -611,8 +788,11 @@ static sigset_t normal_mask;
_initialize_linux_nat. */
static sigset_t suspend_mask;

-/* Signals to block to make that sigsuspend work. */
-static sigset_t blocked_mask;
+/* SIGCHLD action for synchronous mode. */
+struct sigaction sync_sigchld_action;
+
+/* SIGCHLD action for asynchronous mode. */
+static struct sigaction async_sigchld_action;
\f

/* Prototypes for local functions. */
@@ -837,16 +1017,12 @@ int
lin_lwp_attach_lwp (ptid_t ptid)
{
struct lwp_info *lp;
+ int async_events_were_enabled = 0;

gdb_assert (is_lwp (ptid));

- /* Make sure SIGCHLD is blocked. We don't want SIGCHLD events
- to interrupt either the ptrace() or waitpid() calls below. */
- if (!sigismember (&blocked_mask, SIGCHLD))
- {
- sigaddset (&blocked_mask, SIGCHLD);
- sigprocmask (SIG_BLOCK, &blocked_mask, NULL);
- }
+ if (target_can_async_p ())
+ async_events_were_enabled = linux_nat_async_events (0);

lp = find_lwp_pid (ptid);

@@ -919,10 +1095,39 @@ lin_lwp_attach_lwp (ptid_t ptid)
lp->stopped = 1;
}

+ if (async_events_were_enabled)
+ linux_nat_async_events (1);
+
return 0;
}

static void
+linux_nat_create_inferior (char *exec_file, char *allargs, char **env,
+ int from_tty)
+{
+ int saved_async = 0;
+
+ /* The fork_child mechanism is synchronous and calls target_wait, so
+ we have to mask the async mode. */
+
+ if (target_can_async_p ())
+ saved_async = linux_nat_async_mask (0);
+ else
+ {
+ /* Restore the original signal mask. */
+ sigprocmask (SIG_SETMASK, &normal_mask, NULL);
+ /* Make sure we don't block SIGCHLD during a sigsuspend. */
+ suspend_mask = normal_mask;
+ sigdelset (&suspend_mask, SIGCHLD);
+ }
+
+ linux_ops->to_create_inferior (exec_file, allargs, env, from_tty);
+
+ if (saved_async)
+ linux_nat_async_mask (saved_async);
+}
+
+static void
linux_nat_attach (char *args, int from_tty)
{
struct lwp_info *lp;
@@ -934,6 +1139,15 @@ linux_nat_attach (char *args, int from_t
attach all of them. */
linux_ops->to_attach (args, from_tty);

+ if (!target_can_async_p ())
+ {
+ /* Restore the original signal mask. */
+ sigprocmask (SIG_SETMASK, &normal_mask, NULL);
+ /* Make sure we don't block SIGCHLD during a sigsuspend. */
+ suspend_mask = normal_mask;
+ sigdelset (&suspend_mask, SIGCHLD);
+ }
+
/* 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. */
@@ -961,9 +1175,14 @@ linux_nat_attach (char *args, int from_t
lp->status = W_STOPCODE (SIGSTOP);
lp->resumed = 1;
if (debug_linux_nat)
+ fprintf_unfiltered (gdb_stdlog,
+ "LNA: waitpid %ld, faking SIGSTOP\n", (long) pid);
+ if (target_can_async_p ())
{
- fprintf_unfiltered (gdb_stdlog,
- "LLA: waitpid %ld, faking SIGSTOP\n", (long) pid);
+ /* Wake event loop with special token, to get to WFI. */
+ linux_nat_event_pipe_push (-1, -1, -1);
+ /* Register in the event loop. */
+ target_async (inferior_event_handler, 0);
}
}

@@ -1020,6 +1239,7 @@ detach_callback (struct lwp_info *lp, vo
target_pid_to_str (lp->ptid),
strsignal (WSTOPSIG (lp->status)));

+ drain_queued_events (GET_LWP (lp->ptid));
delete_lwp (lp->ptid);
}

@@ -1029,6 +1249,10 @@ detach_callback (struct lwp_info *lp, vo
static void
linux_nat_detach (char *args, int from_tty)
{
+ int pid;
+ if (target_can_async_p ())
+ linux_nat_async (NULL, 0);
+
iterate_over_lwps (detach_callback, NULL);

/* Only the initial process should be left right now. */
@@ -1039,12 +1263,12 @@ linux_nat_detach (char *args, int from_t
/* Destroy LWP info; it's no longer valid. */
init_lwp_list ();

- /* Restore the original signal mask. */
- sigprocmask (SIG_SETMASK, &normal_mask, NULL);
- sigemptyset (&blocked_mask);
-
- inferior_ptid = pid_to_ptid (GET_PID (inferior_ptid));
+ pid = GET_PID (inferior_ptid);
+ inferior_ptid = pid_to_ptid (pid);
linux_ops->to_detach (args, from_tty);
+
+ if (target_can_async_p ())
+ drain_queued_events (pid);
}

/* Resume LP. */
@@ -1098,6 +1322,10 @@ linux_nat_resume (ptid_t ptid, int step,

prune_lwps ();

+ if (target_can_async_p ())
+ /* Block events while we're here. */
+ linux_nat_async_events (0);
+
/* A specific PTID means `step only this process id'. */
resume_all = (PIDGET (ptid) == -1);

@@ -1162,6 +1390,13 @@ linux_nat_resume (ptid_t ptid, int step,
"LLR: Short circuiting for status 0x%x\n",
lp->status);

+ if (target_can_async_p ())
+ {
+ /* Wake event loop with special token, to get to WFI. */
+ linux_nat_event_pipe_push (-1, -1, -1);
+
+ target_async (inferior_event_handler, 0);
+ }
return;
}

@@ -1181,6 +1416,12 @@ linux_nat_resume (ptid_t ptid, int step,
step ? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
target_pid_to_str (ptid),
signo ? strsignal (signo) : "0");
+
+ if (target_can_async_p ())
+ {
+ target_executing = 1;
+ target_async (inferior_event_handler, 0);
+ }
}

/* Issue kill to specified lwp. */
@@ -2032,6 +2273,57 @@ linux_nat_filter_event (int lwpid, int s
return lp;
}

+/* Get the events stored in the pipe into the local queue, so they are
+ accessible to queued_waitpid. We need to do this, since it is not
+ always the case that the event at the head of the pipe is the event
+ we want. */
+
+static void
+pipe_to_local_event_queue (void)
+{
+ if (debug_linux_nat_async)
+ fprintf_unfiltered (gdb_stdlog,
+ "PTLEQ: linux_nat_num_queued_events(%d)\n",
+ linux_nat_num_queued_events);
+ while (linux_nat_num_queued_events)
+ {
+ int lwpid, status, options;
+
+ lwpid = linux_nat_event_pipe_pop (&status, &options);
+ if (lwpid == -1 && status == -1 && options == -1)
+ /* Special wake up event loop token. */
+ continue;
+
+ gdb_assert (lwpid > 0);
+ push_waitpid (lwpid, status, options);
+ }
+}
+
+/* Get the unprocessed events stored in the local queue back into the
+ pipe, so the event loop realizes there's something else to
+ process. */
+
+static void
+local_event_queue_to_pipe (void)
+{
+ struct waitpid_result *w = waitpid_queue;
+ while (w)
+ {
+ struct waitpid_result *next = w->next;
+ linux_nat_event_pipe_push (w->pid,
+ w->status,
+ w->options);
+ xfree (w);
+ w = next;
+ }
+ waitpid_queue = NULL;
+
+ if (debug_linux_nat_async)
+ fprintf_unfiltered (gdb_stdlog,
+ "LEQTP: linux_nat_num_queued_events(%d)\n",
+ linux_nat_num_queued_events);
+}
+
static ptid_t
linux_nat_wait (ptid_t ptid, struct target_waitstatus *ourstatus)
{
@@ -2041,6 +2333,9 @@ linux_nat_wait (ptid_t ptid, struct targ
pid_t pid = PIDGET (ptid);
sigset_t flush_mask;

+ if (debug_linux_nat_async)
+ fprintf_unfiltered (gdb_stdlog, "LLW: enter\n");
+
/* The first time we get here after starting a new inferior, we may
not have added it to the LWP list yet - this is the earliest
moment at which we know its PID. */
@@ -2056,12 +2351,9 @@ linux_nat_wait (ptid_t ptid, struct targ

sigemptyset (&flush_mask);

- /* Make sure SIGCHLD is blocked. */
- if (!sigismember (&blocked_mask, SIGCHLD))
- {
- sigaddset (&blocked_mask, SIGCHLD);
- sigprocmask (SIG_BLOCK, &blocked_mask, NULL);
- }
+ if (target_can_async_p ())
+ /* Block events while we're here. */
+ target_async (NULL, 0);

retry:

@@ -2085,7 +2377,7 @@ retry:
target_pid_to_str (lp->ptid));
}

- /* But if we don't fine one, we'll have to wait, and check both
+ /* But if we don't find one, we'll have to wait, and check both
cloned and uncloned processes. We start with the cloned
processes. */
options = __WCLONE | WNOHANG;
@@ -2144,15 +2436,24 @@ retry:
stop_wait_callback (lp, NULL);
}

- set_sigint_trap (); /* Causes SIGINT to be passed on to the
- attached process. */
- set_sigio_trap ();
+ if (!target_can_async_p ())
+ {
+ /* Causes SIGINT to be passed on to the attached process. */
+ set_sigint_trap ();
+ set_sigio_trap ();
+ }

while (status == 0)
{
pid_t lwpid;

- lwpid = my_waitpid (pid, &status, options);
+ if (target_can_async_p ())
+ /* In async mode, don't ever block. Only look at the locally
+ queued events. */
+ lwpid = queued_waitpid (pid, &status, options);
+ else
+ lwpid = my_waitpid (pid, &status, options);
+
if (lwpid > 0)
{
gdb_assert (pid == -1 || lwpid == pid);
@@ -2180,17 +2481,38 @@ retry:
/* Alternate between checking cloned and uncloned processes. */
options ^= __WCLONE;

- /* And suspend every time we have checked both. */
+ /* And every time we have checked both:
+ In async mode, return to event loop;
+ In sync mode, suspend waiting for a SIGCHLD signal. */
if (options & __WCLONE)
- sigsuspend (&suspend_mask);
+ {
+ if (target_can_async_p ())
+ {
+ /* No interesting event. */
+ ourstatus->kind = TARGET_WAITKIND_IGNORE;
+
+ /* Get ready for the next event. */
+ target_async (inferior_event_handler, 0);
+
+ if (debug_linux_nat_async)
+ fprintf_unfiltered (gdb_stdlog, "LLW: exit (ignore)\n");
+
+ return minus_one_ptid;
+ }
+
+ sigsuspend (&suspend_mask);
+ }
}

/* We shouldn't end up here unless we want to try again. */
gdb_assert (status == 0);
}

- clear_sigio_trap ();
- clear_sigint_trap ();
+ if (!target_can_async_p ())
+ {
+ clear_sigio_trap ();
+ clear_sigint_trap ();
+ }

gdb_assert (lp);

@@ -2287,6 +2609,13 @@ retry:
else
store_waitstatus (ourstatus, status);

+ /* Get ready for the next event. */
+ if (target_can_async_p ())
+ target_async (inferior_event_handler, 0);
+
+ if (debug_linux_nat_async)
+ fprintf_unfiltered (gdb_stdlog, "LLW: exit\n");
+
return lp->ptid;
}

@@ -2366,6 +2695,9 @@ linux_nat_kill (void)
ptid_t last_ptid;
int status;

+ if (target_can_async_p ())
+ target_async (NULL, 0);
+
/* If we're stopped while forking and we haven't followed yet,
kill the other task. We need to do this first because the
parent will be sleeping if this is a vfork. */
@@ -2380,7 +2712,10 @@ linux_nat_kill (void)
}

if (forks_exist_p ())
- linux_fork_killall ();
+ {
+ linux_fork_killall ();
+ drain_queued_events (-1);
+ }
else
{
/* Kill all LWP's ... */
@@ -2401,13 +2736,13 @@ linux_nat_mourn_inferior (void)
/* Destroy LWP info; it's no longer valid. */
init_lwp_list ();

- /* Restore the original signal mask. */
- sigprocmask (SIG_SETMASK, &normal_mask, NULL);
- sigemptyset (&blocked_mask);
-
if (! forks_exist_p ())
- /* Normal case, no other forks available. */
- linux_ops->to_mourn_inferior ();
+ {
+ /* Normal case, no other forks available. */
+ if (target_can_async_p ())
+ linux_nat_async (NULL, 0);
+ linux_ops->to_mourn_inferior ();
+ }
else
/* Multi-fork case. The current inferior_ptid has exited, but
there are other viable forks to debug. Delete the exiting
@@ -2475,6 +2810,13 @@ linux_nat_pid_to_str (ptid_t ptid)
static void
sigchld_handler (int signo)
{
+ if (linux_nat_async_enabled
+ && linux_nat_async_events_enabled
+ && signo == SIGCHLD)
+ /* It is *always* a bug to hit this. */
+ internal_error (__FILE__, __LINE__,
+ "sigchld_handler called when async events are enabled");
+
/* Do nothing. The only reason for this handler is that it allows
us to use sigsuspend in linux_nat_wait above to wait for the
arrival of a SIGCHLD. */
@@ -3233,6 +3575,376 @@ linux_trad_target (CORE_ADDR (*register_
return t;
}

+/* Controls if async mode is permitted. */
+static int linux_async_permitted = 0;
+
+/* The set command writes to this variable. If the inferior is
+ executing, linux_nat_async_permitted is *not* updated. */
+static int linux_async_permitted_1 = 0;
+
+static void
+set_maintenance_linux_async_permitted (char *args, int from_tty,
+ struct cmd_list_element *c)
+{
+ if (target_has_execution)
+ {
+ linux_async_permitted_1 = linux_async_permitted;
+ error (_("Cannot change this setting while the inferior is running."));
+ }
+
+ linux_async_permitted = linux_async_permitted_1;
+ linux_nat_set_async_mode (linux_async_permitted);
+}
+
+static void
+show_maintenance_linux_async_permitted (struct ui_file *file, int from_tty,
+ struct cmd_list_element *c, const char *value)
+{
+ fprintf_filtered (file, _("\
+Controlling the GNU/Linux inferior in asynchronous mode is %s.\n"),
+ value);
+}
+
+/* target_is_async_p implementation. */
+
+static int
+linux_nat_is_async_p (void)
+{
+ /* NOTE: palves 2008-03-21: We're only async when the user requests
+ it explicitly with the "maintenance set linux-async" command.
+ Someday, linux will always be async. */
+ if (!linux_async_permitted)
+ return 0;
+
+ return 1;
+}
+
+/* target_can_async_p implementation. */
+
+static int
+linux_nat_can_async_p (void)
+{
+ /* NOTE: palves 2008-03-21: We're only async when the user requests
+ it explicitly with the "maintenance set linux-async" command.
+ Someday, linux will always be async. */
+ if (!linux_async_permitted)
+ return 0;
+
+ /* See target.h/target_async_mask. */
+ return linux_nat_async_mask_value;
+}
+
+/* target_async_mask implementation. */
+
+static int
+linux_nat_async_mask (int mask)
+{
+ int current_state;
+ current_state = linux_nat_async_mask_value;
+
+ if (current_state != mask)
+ {
+ if (mask == 0)
+ {
+ linux_nat_async (NULL, 0);
+ linux_nat_async_mask_value = mask;
+ /* We're in sync mode. Make sure SIGCHLD isn't handled by
+ async_sigchld_handler when we come out of sigsuspend in
+ linux_nat_wait. */
+ sigaction (SIGCHLD, &sync_sigchld_action, NULL);
+ }
+ else
+ {
+ /* Restore the async handler. */
+ sigaction (SIGCHLD, &async_sigchld_action, NULL);
+ linux_nat_async_mask_value = mask;
+ linux_nat_async (inferior_event_handler, 0);
+ }
+ }
+
+ return current_state;
+}
+
+/* Pop an event from the event pipe. */
+
+static int
+linux_nat_event_pipe_pop (int* ptr_status, int* ptr_options)
+{
+ struct waitpid_result event = {0};
+ int ret;
+
+ do
+ {
+ ret = read (linux_nat_event_pipe[0], &event, sizeof (event));
+ }
+ while (ret == -1 && errno == EINTR);
+
+ gdb_assert (ret == sizeof (event));
+
+ *ptr_status = event.status;
+ *ptr_options = event.options;
+
+ linux_nat_num_queued_events--;
+
+ return event.pid;
+}
+
+/* Push an event into the event pipe. */
+
+static void
+linux_nat_event_pipe_push (int pid, int status, int options)
+{
+ int ret;
+ struct waitpid_result event = {0};
+ event.pid = pid;
+ event.status = status;
+ event.options = options;
+
+ do
+ {
+ ret = write (linux_nat_event_pipe[1], &event, sizeof (event));
+ gdb_assert ((ret == -1 && errno == EINTR) || ret == sizeof (event));
+ } while (ret == -1 && errno == EINTR);
+
+ linux_nat_num_queued_events++;
+}
+
+static void
+get_pending_events (void)
+{
+ int status, options, pid;
+
+ if (!linux_nat_async_enabled || !linux_nat_async_events_enabled)
+ internal_error (__FILE__, __LINE__,
+ "get_pending_events called with async masked");
+
+ while (1)
+ {
+ status = 0;
+ options = __WCLONE | WNOHANG;
+
+ do
+ {
+ pid = waitpid (-1, &status, options);
+ }
+ while (pid == -1 && errno == EINTR);
+
+ if (pid <= 0)
+ {
+ options = WNOHANG;
+ do
+ {
+ pid = waitpid (-1, &status, options);
+ }
+ while (pid == -1 && errno == EINTR);
+ }
+
+ if (pid <= 0)
+ /* No more children reporting events. */
+ break;
+
+ if (debug_linux_nat_async)
+ fprintf_unfiltered (gdb_stdlog, "\
+get_pending_events: pid(%d), status(%x), options (%x)\n",
+ pid, status, options);
+
+ linux_nat_event_pipe_push (pid, status, options);
+ }
+
+ if (debug_linux_nat_async)
+ fprintf_unfiltered (gdb_stdlog, "\
+get_pending_events: linux_nat_num_queued_events(%d)\n",
+ linux_nat_num_queued_events);
+}
+
+/* SIGCHLD handler for async mode. */
+
+static void
+async_sigchld_handler (int signo)
+{
+ if (debug_linux_nat_async)
+ fprintf_unfiltered (gdb_stdlog, "async_sigchld_handler\n");
+
+ get_pending_events ();
+}
+
+/* Enable or disable async SIGCHLD handling. */
+
+static int
+linux_nat_async_events (int enable)
+{
+ int current_state = linux_nat_async_events_enabled;
+
+ if (debug_linux_nat_async)
+ fprintf_unfiltered (gdb_stdlog,
+ "LNAE: enable(%d): linux_nat_async_events_enabled(%d), "
+ "linux_nat_num_queued_events(%d)\n",
+ enable, linux_nat_async_events_enabled,
+ linux_nat_num_queued_events);
+
+ if (current_state != enable)
+ {
+ sigset_t mask;
+ sigemptyset (&mask);
+ sigaddset (&mask, SIGCHLD);
+ if (enable)
+ {
+ /* Unblock target events. */
+ linux_nat_async_events_enabled = 1;
+
+ local_event_queue_to_pipe ();
+ /* While in masked async, we may have not collected all the
+ pending events. Get them out now. */
+ get_pending_events ();
+ sigprocmask (SIG_UNBLOCK, &mask, NULL);
+ }
+ else
+ {
+ /* Block target events. */
+ sigprocmask (SIG_BLOCK, &mask, NULL);
+ linux_nat_async_events_enabled = 0;
+ /* Get events out of queue, and make them available to
+ queued_waitpid / my_waitpid. */
+ pipe_to_local_event_queue ();
+ }
+ }
+
+ return current_state;
+}
+
+static int async_terminal_is_ours = 1;
+
+/* target_terminal_inferior implementation. */
+
+static void
+linux_nat_terminal_inferior (void)
+{
+ if (!target_is_async_p ())
+ {
+ /* Async mode is disabled. */
+ terminal_inferior ();
+ return;
+ }
+
+ /* GDB should never give the terminal to the inferior, if the
+ inferior is running in the background (run&, continue&, etc.).
+ This check can be removed when the common code is fixed. */
+ if (!sync_execution)
+ return;
+
+ terminal_inferior ();
+
+ if (!async_terminal_is_ours)
+ return;
+
+ delete_file_handler (input_fd);
+ async_terminal_is_ours = 0;
+ set_sigint_trap ();
+}
+
+/* target_terminal_ours implementation. */
+
+void
+linux_nat_terminal_ours (void)
+{
+ if (!target_is_async_p ())
+ {
+ /* Async mode is disabled. */
+ terminal_ours ();
+ return;
+ }
+
+ /* GDB should never give the terminal to the inferior if the
+ inferior is running in the background (run&, continue&, etc.),
+ but claiming it sure should. */
+ terminal_ours ();
+
+ if (!sync_execution)
+ return;
+
+ if (async_terminal_is_ours)
+ return;
+
+ clear_sigint_trap ();
+ add_file_handler (input_fd, stdin_event_handler, 0);
+ async_terminal_is_ours = 1;
+}
+
+static void (*async_client_callback) (enum inferior_event_type event_type,
+ void *context);
+static void *async_client_context;
+
+static void
+linux_nat_async_file_handler (int error, gdb_client_data client_data)
+{
+ async_client_callback (INF_REG_EVENT, async_client_context);
+}
+
+/* target_async implementation. */
+
+static void
+linux_nat_async (void (*callback) (enum inferior_event_type event_type,
+ void *context), void *context)
+{
+ if (linux_nat_async_mask_value == 0 || !linux_nat_async_enabled)
+ internal_error (__FILE__, __LINE__,
+ "Calling target_async when async is masked");
+
+ if (callback != NULL)
+ {
+ async_client_callback = callback;
+ async_client_context = context;
+ add_file_handler (linux_nat_event_pipe[0],
+ linux_nat_async_file_handler, NULL);
+
+ linux_nat_async_events (1);
+ }
+ else
+ {
+ async_client_callback = callback;
+ async_client_context = context;
+
+ linux_nat_async_events (0);
+ delete_file_handler (linux_nat_event_pipe[0]);
+ }
+ return;
+}
+
+/* Enable/Disable async mode. */
+
+static void
+linux_nat_set_async_mode (int on)
+{
+ if (linux_nat_async_enabled != on)
+ {
+ if (on)
+ {
+ gdb_assert (waitpid_queue == NULL);
+ sigaction (SIGCHLD, &async_sigchld_action, NULL);
+
+ if (pipe (linux_nat_event_pipe) == -1)
+ internal_error (__FILE__, __LINE__,
+ "creating event pipe failed.");
+
+ fcntl (linux_nat_event_pipe[0], F_SETFL, O_NONBLOCK);
+ fcntl (linux_nat_event_pipe[1], F_SETFL, O_NONBLOCK);
+ }
+ else
+ {
+ sigaction (SIGCHLD, &sync_sigchld_action, NULL);
+
+ drain_queued_events (-1);
+
+ linux_nat_num_queued_events = 0;
+ close (linux_nat_event_pipe[0]);
+ close (linux_nat_event_pipe[1]);
+ linux_nat_event_pipe[0] = linux_nat_event_pipe[1] = -1;
+
+ }
+ }
+ linux_nat_async_enabled = on;
+}
+
void
linux_nat_add_target (struct target_ops *t)
{
@@ -3244,6 +3956,7 @@ linux_nat_add_target (struct target_ops
linux_ops = &linux_ops_saved;

/* Override some methods for multithreading. */
+ t->to_create_inferior = linux_nat_create_inferior;
t->to_attach = linux_nat_attach;
t->to_detach = linux_nat_detach;
t->to_resume = linux_nat_resume;
@@ -3255,6 +3968,13 @@ linux_nat_add_target (struct target_ops
t->to_pid_to_str = linux_nat_pid_to_str;
t->to_has_thread_control = tc_schedlock;

+ t->to_can_async_p = linux_nat_can_async_p;
+ t->to_is_async_p = linux_nat_is_async_p;
+ t->to_async = linux_nat_async;
+ t->to_async_mask = linux_nat_async_mask;
+ t->to_terminal_inferior = linux_nat_terminal_inferior;
+ t->to_terminal_ours = linux_nat_terminal_ours;
+
/* We don't change the stratum; this target will sit at
process_stratum and thread_db will set at thread_stratum. This
is a little strange, since this is a multi-threaded-capable
@@ -3292,7 +4012,7 @@ linux_nat_get_siginfo (ptid_t ptid)
void
_initialize_linux_nat (void)
{
- struct sigaction action;
+ sigset_t mask;

add_info ("proc", linux_nat_info_proc_cmd, _("\
Show /proc process information about any running process.\n\
@@ -3303,27 +4023,63 @@ Specify any of the following keywords fo
status -- list a different bunch of random process info.\n\
all -- list all available /proc info."));

- /* Save the original signal mask. */
+ add_setshow_zinteger_cmd ("lin-lwp", class_maintenance,
+ &debug_linux_nat, _("\
+Set debugging of GNU/Linux lwp module."), _("\
+Show debugging of GNU/Linux lwp module."), _("\
+Enables printf debugging output."),
+ NULL,
+ show_debug_linux_nat,
+ &setdebuglist, &showdebuglist);
+
+ add_setshow_zinteger_cmd ("lin-lwp-async", class_maintenance,
+ &debug_linux_nat_async, _("\
+Set debugging of GNU/Linux async lwp module."), _("\
+Show debugging of GNU/Linux async lwp module."), _("\
+Enables printf debugging output."),
+ NULL,
+ show_debug_linux_nat_async,
+ &setdebuglist, &showdebuglist);
+
+ add_setshow_boolean_cmd ("linux-async", class_maintenance,
+ &linux_async_permitted_1, _("\
+Set whether gdb controls the GNU/Linux inferior in asynchronous mode."), _("\
+Show whether gdb controls the GNU/Linux inferior in asynchronous mode."), _("\
+Tells gdb whether to control the GNU/Linux inferior in asynchronous mode."),
+ set_maintenance_linux_async_permitted,
+ show_maintenance_linux_async_permitted,
+ &maintenance_set_cmdlist,
+ &maintenance_show_cmdlist);
+
+ /* Block SIGCHLD by default. Doing this early prevents it getting
+ unblocked if an exception is thrown due to an error while the
+ inferior is starting (sigsetjmp/siglongjmp). */
+ sigemptyset (&mask);
+ sigaddset (&mask, SIGCHLD);
+ sigprocmask (SIG_BLOCK, &mask, NULL);
+
+ /* Save this mask as the default. */
sigprocmask (SIG_SETMASK, NULL, &normal_mask);

- action.sa_handler = sigchld_handler;
- sigemptyset (&action.sa_mask);
- action.sa_flags = SA_RESTART;
- sigaction (SIGCHLD, &action, NULL);
+ /* The synchronous SIGCHLD handler. */
+ sync_sigchld_action.sa_handler = sigchld_handler;
+ sigemptyset (&sync_sigchld_action.sa_mask);
+ sync_sigchld_action.sa_flags = SA_RESTART;
+
+ /* Make it the default. */
+ sigaction (SIGCHLD, &sync_sigchld_action, NULL);

/* Make sure we don't block SIGCHLD during a sigsuspend. */
sigprocmask (SIG_SETMASK, NULL, &suspend_mask);
sigdelset (&suspend_mask, SIGCHLD);

- sigemptyset (&blocked_mask);
+ /* SIGCHLD handler for async mode. */
+ async_sigchld_action.sa_handler = async_sigchld_handler;
+ sigemptyset (&async_sigchld_action.sa_mask);
+ async_sigchld_action.sa_flags = SA_RESTART;

- add_setshow_zinteger_cmd ("lin-lwp", no_class, &debug_linux_nat, _("\
-Set debugging of GNU/Linux lwp module."), _("\
-Show debugging of GNU/Linux lwp module."), _("\
-Enables printf debugging output."),
- NULL,
- show_debug_linux_nat,
- &setdebuglist, &showdebuglist);
+ /* Install the default mode. */
+ linux_nat_set_async_mode (linux_async_permitted);
}
\f

@@ -3359,7 +4115,9 @@ lin_thread_get_thread_signals (sigset_t
{
struct sigaction action;
int restart, cancel;
+ sigset_t blocked_mask;

+ sigemptyset (&blocked_mask);
sigemptyset (set);

restart = get_signo ("__pthread_sig_restart");
Index: linux-thread-db.c
===================================================================
RCS file: /cvs/src/src/gdb/linux-thread-db.c,v
retrieving revision 1.38
diff -u -p -r1.38 linux-thread-db.c
--- linux-thread-db.c 21 Mar 2008 15:44:53 -0000 1.38
+++ linux-thread-db.c 21 Mar 2008 17:05:52 -0000
@@ -824,6 +824,9 @@ thread_db_wait (ptid_t ptid, struct targ

ptid = target_beneath->to_wait (ptid, ourstatus);

+ if (ourstatus->kind == TARGET_WAITKIND_IGNORE)
+ return ptid;
+
if (ourstatus->kind == TARGET_WAITKIND_EXITED
|| ourstatus->kind == TARGET_WAITKIND_SIGNALLED)
return pid_to_ptid (-1);
@@ -885,6 +888,31 @@ thread_db_mourn_inferior (void)
}

static int
+thread_db_can_async_p (void)
+{
+ return target_beneath->to_can_async_p ();
+}
+
+static int
+thread_db_is_async_p (void)
+{
+ return target_beneath->to_is_async_p ();
+}
+
+static void
+thread_db_async (void (*callback) (enum inferior_event_type event_type,
+ void *context), void *context)
+{
+ return target_beneath->to_async (callback, context);
+}
+
+static int
+thread_db_async_mask (int mask)
+{
+ return target_beneath->to_async_mask (mask);
+}
+
+static int
find_new_threads_callback (const td_thrhandle_t *th_p, void *data)
{
td_thrinfo_t ti;
@@ -1056,6 +1084,10 @@ init_thread_db_ops (void)
thread_db_ops.to_get_thread_local_address
= thread_db_get_thread_local_address;
thread_db_ops.to_extra_thread_info = thread_db_extra_thread_info;
+ thread_db_ops.to_can_async_p = thread_db_can_async_p;
+ thread_db_ops.to_is_async_p = thread_db_is_async_p;
+ thread_db_ops.to_async = thread_db_async;
+ thread_db_ops.to_async_mask = thread_db_async_mask;
thread_db_ops.to_magic = OPS_MAGIC;
}

Index: remote.c
===================================================================
RCS file: /cvs/src/src/gdb/remote.c,v
retrieving revision 1.285
diff -u -p -r1.285 remote.c
--- remote.c 14 Mar 2008 18:57:43 -0000 1.285
+++ remote.c 21 Mar 2008 17:05:53 -0000
@@ -481,6 +481,8 @@ static struct target_ops extended_remote
extended_remote_ops, but with asynchronous support. */
static struct target_ops remote_async_ops;

+static int remote_async_mask_value = 1;
+
static struct target_ops extended_async_remote_ops;

/* FIXME: cagney/1999-09-23: Even though getpkt was called with
@@ -7176,6 +7178,12 @@ remote_command (char *args, int from_tty
help_list (remote_cmdlist, "remote ", -1, gdb_stdout);
}

+static int
+remote_return_zero (void)
+{
+ return 0;
+}
+
static void
init_remote_ops (void)
{
@@ -7229,6 +7237,8 @@ Specify the serial device it is connecte
remote_ops.to_flash_erase = remote_flash_erase;
remote_ops.to_flash_done = remote_flash_done;
remote_ops.to_read_description = remote_read_description;
+ remote_ops.to_can_async_p = remote_return_zero;
+ remote_ops.to_is_async_p = remote_return_zero;
}

/* Set up the extended remote vector by making a copy of the standard
@@ -7256,14 +7266,14 @@ static int
remote_can_async_p (void)
{
/* We're async whenever the serial device is. */
- return (current_target.to_async_mask_value) && serial_can_async_p (remote_desc);
+ return remote_async_mask_value && serial_can_async_p (remote_desc);
}

static int
remote_is_async_p (void)
{
/* We're async whenever the serial device is. */
- return (current_target.to_async_mask_value) && serial_is_async_p (remote_desc);
+ return remote_async_mask_value && serial_is_async_p (remote_desc);
}

/* Pass the SERIAL event on and up to the client. One day this code
@@ -7287,7 +7297,7 @@ static void
remote_async (void (*callback) (enum inferior_event_type event_type,
void *context), void *context)
{
- if (current_target.to_async_mask_value == 0)
+ if (remote_async_mask_value == 0)
internal_error (__FILE__, __LINE__,
_("Calling remote_async when async is masked"));

@@ -7301,6 +7311,14 @@ remote_async (void (*callback) (enum inf
serial_async (remote_desc, NULL, NULL);
}

+static int
+remote_async_mask (int new_mask)
+{
+ int curr_mask = remote_async_mask_value;
+ remote_async_mask_value = new_mask;
+ return curr_mask;
+}
+
/* Target async and target extended-async.

This are temporary targets, until it is all tested. Eventually
@@ -7360,7 +7378,7 @@ Specify the serial device it is connecte
remote_async_ops.to_can_async_p = remote_can_async_p;
remote_async_ops.to_is_async_p = remote_is_async_p;
remote_async_ops.to_async = remote_async;
- remote_async_ops.to_async_mask_value = 1;
+ remote_async_ops.to_async_mask = remote_async_mask;
remote_async_ops.to_magic = OPS_MAGIC;
remote_async_ops.to_memory_map = remote_memory_map;
remote_async_ops.to_flash_erase = remote_flash_erase;
Index: Makefile.in
===================================================================
RCS file: /cvs/src/src/gdb/Makefile.in,v
retrieving revision 1.993
diff -u -p -r1.993 Makefile.in
--- Makefile.in 16 Mar 2008 08:50:43 -0000 1.993
+++ Makefile.in 21 Mar 2008 17:05:54 -0000
@@ -2351,7 +2351,7 @@ linux-nat.o: linux-nat.c $(defs_h) $(inf
$(gdb_wait_h) $(gdb_assert_h) $(linux_nat_h) $(gdbthread_h) \
$(gdbcmd_h) $(regcache_h) $(regset_h) $(inf_ptrace_h) $(auxv_h) \
$(elf_bfd_h) $(gregset_h) $(gdbcore_h) $(gdbthread_h) $(gdb_stat_h) \
- $(linux_fork_h)
+ $(linux_fork_h) $(inf_loop_h) $(event_loop_h) $(event_top_h)
linux-thread-db.o: linux-thread-db.c $(defs_h) $(gdb_assert_h) \
$(gdb_proc_service_h) $(gdb_thread_db_h) $(bfd_h) $(exceptions_h) \
$(gdbthread_h) $(inferior_h) $(symfile_h) $(objfiles_h) $(target_h) \
Index: doc/ChangeLog
===================================================================
RCS file: /cvs/src/src/gdb/doc/ChangeLog,v
retrieving revision 1.757
diff -u -p -r1.757 ChangeLog
--- doc/ChangeLog 21 Mar 2008 15:02:37 -0000 1.757
+++ doc/ChangeLog 21 Mar 2008 17:05:55 -0000
@@ -1,3 +1,9 @@
+2008-03-21 Pedro Alves <pedro@codesourcery.com>
+
+ * gdb.texinfo (Debugging Output): Document
+ "set/show debug lin-lwp-async".
+ (Maintenance Commands): Document "maint set/show linux-async".
+
2008-03-21 Daniel Jacobowitz <dan@codesourcery.com>

* gdb.texinfo (Expressions): Update description of malloced arrays.
Index: doc/gdb.texinfo
===================================================================
RCS file: /cvs/src/src/gdb/doc/gdb.texinfo,v
retrieving revision 1.476
diff -u -p -r1.476 gdb.texinfo
--- doc/gdb.texinfo 21 Mar 2008 15:02:37 -0000 1.476
+++ doc/gdb.texinfo 21 Mar 2008 17:06:01 -0000
@@ -16407,6 +16407,12 @@ Displays the current state of @value{GDB
Turns on or off debugging messages from the Linux LWP debug support.
@item show debug lin-lwp
Show the current state of Linux LWP debugging messages.
+@item set debug lin-lwp-async
+@cindex @sc{gnu}/Linux LWP async debug messages
+@cindex Linux lightweight processes
+Turns on or off debugging messages from the Linux LWP async debug support.
+@item show debug lin-lwp-async
+Show the current state of Linux LWP async debugging messages.
@item set debug observer
@cindex observer debugging info
Turns on or off display of @value{GDBN} observer debugging. This
@@ -23242,6 +23248,16 @@ data in a @file{gmon.out} file, be sure
Configuring with @samp{--enable-profiling} arranges for @value{GDBN} to be
compiled with the @samp{-pg} compiler option.

+@kindex maint set linux-async
+@kindex maint show linux-async
+@cindex asynchronous support
+@item maint set linux-async
+@itemx maint show linux-async
+Control the GNU/Linux native asynchronous support of @value{GDBN}.
+
+GNU/Linux native asynchronous support will be disabled until you use
+the @samp{maint set linux-async} command to enable it.
+
@kindex maint show-debug-regs
@cindex x86 hardware debug registers
@item maint show-debug-regs