From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 22433 invoked by alias); 10 Mar 2010 03:49:17 -0000 Received: (qmail 22422 invoked by uid 22791); 10 Mar 2010 03:49:15 -0000 X-SWARE-Spam-Status: No, hits=-7.2 required=5.0 tests=AWL,BAYES_00,RCVD_IN_DNSWL_HI,SPF_HELO_PASS X-Spam-Check-By: sourceware.org Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Wed, 10 Mar 2010 03:49:09 +0000 Received: from int-mx04.intmail.prod.int.phx2.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.17]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id o2A3n7YF019461 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Tue, 9 Mar 2010 22:49:07 -0500 Received: from ns3.rdu.redhat.com (ns3.rdu.redhat.com [10.11.255.199]) by int-mx04.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id o2A3n6wC015745; Tue, 9 Mar 2010 22:49:06 -0500 Received: from opsy.redhat.com (ovpn01.gateway.prod.ext.phx2.redhat.com [10.5.9.1]) by ns3.rdu.redhat.com (8.13.8/8.13.8) with ESMTP id o2A3n5ar031185; Tue, 9 Mar 2010 22:49:05 -0500 Received: by opsy.redhat.com (Postfix, from userid 500) id 1538837979F; Tue, 9 Mar 2010 20:49:05 -0700 (MST) From: Tom Tromey To: gdb-patches@sourceware.org Subject: [1/2] RFC: reference count breakpoint commands Reply-To: tromey@redhat.com Date: Wed, 10 Mar 2010 03:49:00 -0000 Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org X-SW-Source: 2010-03/txt/msg00376.txt.bz2 I'd appreciate comments on this. Barring comments I will commit it soonish. This adds reference counting for breakpoint commands. This removes a longstanding restriction: you can now change a breakpoint's commands while the commands are running. This patch also sets the stage for the next page. Built and regtested on x86-64 (compile farm). Tom 2010-03-09 Tom Tromey * breakpoint.h (struct counted_command_line): New struct. (struct breakpoint) : Change type. (struct bpstats) : Change type. : New field. * breakpoint.c (alloc_counted_command_line): New function. (incref_counted_command_line): Likewise. (decref_counted_command_line): Likewise. (do_cleanup_counted_command_line): Likewise. (make_cleanup_decref_counted_command_line): Likewise. (breakpoint_set_commands): Use decref_counted_command_line and alloc_counted_command_line. (commands_command): Don't error if breakpoint commands are executing. (commands_from_control_command): Likewise. (bpstat_free): Update. (bpstat_copy): Likewise. (bpstat_clear_actions): Likewise. (bpstat_do_actions_1): Likewise. (bpstat_stop_status): Likewise. (print_one_breakpoint_location): Likewise. (delete_breakpoint): Likewise. (bpstat_alloc): Initialize new field. diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c index bd3330f..e817a23 100644 --- a/gdb/breakpoint.c +++ b/gdb/breakpoint.c @@ -431,6 +431,63 @@ tracepoint_type (const struct breakpoint *b) return (b->type == bp_tracepoint || b->type == bp_fast_tracepoint); } +/* Allocate a new counted_command_line with reference count of 1. + The new structure owns COMMANDS. */ + +static struct counted_command_line * +alloc_counted_command_line (struct command_line *commands) +{ + struct counted_command_line *result + = xmalloc (sizeof (struct counted_command_line)); + result->refc = 1; + result->commands = commands; + return result; +} + +/* Increment reference count. This does nothing if CMD is NULL. */ + +static void +incref_counted_command_line (struct counted_command_line *cmd) +{ + if (cmd) + ++cmd->refc; +} + +/* Decrement reference count. If the reference count reaches 0, + destroy the counted_command_line. Sets *CMDP to NULL. This does + nothing if *CMDP is NULL. */ + +static void +decref_counted_command_line (struct counted_command_line **cmdp) +{ + if (*cmdp) + { + if (--(*cmdp)->refc == 0) + { + free_command_lines (&(*cmdp)->commands); + xfree (*cmdp); + } + *cmdp = NULL; + } +} + +/* A cleanup function that calls decref_counted_command_line. */ + +static void +do_cleanup_counted_command_line (void *arg) +{ + decref_counted_command_line (arg); +} + +/* Create a cleanup that calls decref_counted_command_line on the + argument. */ + +static struct cleanup * +make_cleanup_decref_counted_command_line (struct counted_command_line **cmdp) +{ + return make_cleanup (do_cleanup_counted_command_line, cmdp); +} + /* Default address, symtab and line to put a breakpoint at for "break" command with no arg. if default_breakpoint_valid is zero, the other three are @@ -684,8 +741,8 @@ condition_command (char *arg, int from_tty) void breakpoint_set_commands (struct breakpoint *b, struct command_line *commands) { - free_command_lines (&b->commands); - b->commands = commands; + decref_counted_command_line (&b->commands); + b->commands = alloc_counted_command_line (commands); breakpoints_changed (); observer_notify_breakpoint_modified (b->number); } @@ -698,13 +755,6 @@ commands_command (char *arg, int from_tty) int bnum; struct command_line *l; - /* If we allowed this, we would have problems with when to - free the storage, if we change the commands currently - being read from. */ - - if (executing_breakpoint_commands) - error (_("Can't use the \"commands\" command among a breakpoint's commands.")); - p = arg; bnum = get_number (&p); @@ -737,13 +787,6 @@ commands_from_control_command (char *arg, struct command_line *cmd) char *p; int bnum; - /* If we allowed this, we would have problems with when to - free the storage, if we change the commands currently - being read from. */ - - if (executing_breakpoint_commands) - error (_("Can't use the \"commands\" command among a breakpoint's commands.")); - /* An empty string for the breakpoint number means the last breakpoint, but get_number expects a NULL pointer. */ if (arg && !*arg) @@ -758,12 +801,13 @@ commands_from_control_command (char *arg, struct command_line *cmd) ALL_BREAKPOINTS (b) if (b->number == bnum) { - free_command_lines (&b->commands); + decref_counted_command_line (&b->commands); if (cmd->body_count != 1) error (_("Invalid \"commands\" block structure.")); /* We need to copy the commands because if/while will free the list after it finishes execution. */ - b->commands = copy_command_lines (cmd->body_list[0]); + b->commands + = alloc_counted_command_line (copy_command_lines (cmd->body_list[0])); breakpoints_changed (); observer_notify_breakpoint_modified (b->number); return simple_control; @@ -2553,7 +2597,7 @@ bpstat_free (bpstat bs) { if (bs->old_val != NULL) value_free (bs->old_val); - free_command_lines (&bs->commands); + decref_counted_command_line (&bs->commands); xfree (bs); } @@ -2595,8 +2639,7 @@ bpstat_copy (bpstat bs) { tmp = (bpstat) xmalloc (sizeof (*tmp)); memcpy (tmp, bs, sizeof (*tmp)); - if (bs->commands != NULL) - tmp->commands = copy_command_lines (bs->commands); + incref_counted_command_line (tmp->commands); if (bs->old_val != NULL) { tmp->old_val = value_copy (bs->old_val); @@ -2697,7 +2740,7 @@ bpstat_clear_actions (bpstat bs) { for (; bs != NULL; bs = bs->next) { - free_command_lines (&bs->commands); + decref_counted_command_line (&bs->commands); if (bs->old_val != NULL) { value_free (bs->old_val); @@ -2763,6 +2806,7 @@ bpstat_do_actions_1 (bpstat *bsp) breakpoint_proceeded = 0; for (; bs != NULL; bs = bs->next) { + struct counted_command_line *ccmd; struct command_line *cmd; struct cleanup *this_cmd_tree_chain; @@ -2776,9 +2820,12 @@ bpstat_do_actions_1 (bpstat *bsp) commands are only executed once, we don't need to copy it; we can clear the pointer in the bpstat, and make sure we free the tree when we're done. */ - cmd = bs->commands; - bs->commands = 0; - this_cmd_tree_chain = make_cleanup_free_command_lines (&cmd); + ccmd = bs->commands; + bs->commands = NULL; + this_cmd_tree_chain + = make_cleanup_decref_counted_command_line (&ccmd); + cmd = bs->commands_left; + bs->commands_left = NULL; while (cmd != NULL) { @@ -3161,6 +3208,7 @@ bpstat_alloc (const struct bp_location *bl, bpstat cbs /* Current "bs" value */ bs->breakpoint_at = bl; /* If the condition is false, etc., don't do the commands. */ bs->commands = NULL; + bs->commands_left = NULL; bs->old_val = NULL; bs->print_it = print_it_normal; return bs; @@ -3747,15 +3795,17 @@ bpstat_stop_status (struct address_space *aspace, if (b->silent) bs->print = 0; bs->commands = b->commands; - if (bs->commands - && (strcmp ("silent", bs->commands->line) == 0 - || (xdb_commands && strcmp ("Q", - bs->commands->line) == 0))) + incref_counted_command_line (bs->commands); + bs->commands_left = bs->commands ? bs->commands->commands : NULL; + if (bs->commands_left + && (strcmp ("silent", bs->commands_left->line) == 0 + || (xdb_commands + && strcmp ("Q", + bs->commands_left->line) == 0))) { - bs->commands = bs->commands->next; + bs->commands_left = bs->commands_left->next; bs->print = 0; } - bs->commands = copy_command_lines (bs->commands); } /* Print nothing for this entry if we dont stop or dont print. */ @@ -4422,7 +4472,7 @@ print_one_breakpoint_location (struct breakpoint *b, ui_out_text (uiout, " hits\n"); } - l = b->commands; + l = b->commands ? b->commands->commands : NULL; if (!part_of_multiple && l) { struct cleanup *script_chain; @@ -8841,7 +8891,7 @@ delete_breakpoint (struct breakpoint *bpt) break; } - free_command_lines (&bpt->commands); + decref_counted_command_line (&bpt->commands); if (bpt->cond_string != NULL) xfree (bpt->cond_string); if (bpt->addr_string != NULL) diff --git a/gdb/breakpoint.h b/gdb/breakpoint.h index 6b373a3..1480991 100644 --- a/gdb/breakpoint.h +++ b/gdb/breakpoint.h @@ -374,6 +374,17 @@ DEF_VEC_I(int); typedef struct bp_location *bp_location_p; DEF_VEC_P(bp_location_p); +/* A reference-counted struct command_line. This lets multiple + breakpoints share a single command list. */ +struct counted_command_line +{ + /* The reference count. */ + int refc; + + /* The command list. */ + struct command_line *commands; +}; + /* Note that the ->silent field is not currently used by any commands (though the code is in there if it was to be, and set_raw_breakpoint does set it to 0). I implemented it because I thought it would be @@ -412,7 +423,7 @@ struct breakpoint be continued automatically before really stopping. */ int ignore_count; /* Chain of command lines to execute when this breakpoint is hit. */ - struct command_line *commands; + struct counted_command_line *commands; /* Stack depth (address of frame). If nonzero, break only if fp equals this. */ struct frame_id frame_id; @@ -694,8 +705,11 @@ struct bpstats bpstat next; /* Breakpoint that we are at. */ const struct bp_location *breakpoint_at; - /* Commands left to be done. */ - struct command_line *commands; + /* The associated command list. */ + struct counted_command_line *commands; + /* Commands left to be done. This points somewhere in + base_command. */ + struct command_line *commands_left; /* Old value associated with a watchpoint. */ struct value *old_val;