From b7d2e91626b0e587f3fd5023e79b5079da6baed5 Mon Sep 17 00:00:00 2001 From: Pedro Alves Date: Tue, 3 Feb 2015 16:07:54 +0100 Subject: [PATCH] When disabling target async, remove all target event sources from the event loop The sigall-reverse.exp test occasionally fails with something like this: (gdb) PASS: gdb.reverse/sigall-reverse.exp: send signal TERM continue Continuing. The next instruction is syscall exit_group. It will make the program exit. Do you want to stop the program?([y] or n) FAIL: gdb.reverse/sigall-reverse.exp: continue to signal exit (timeout) FAIL: gdb.reverse/sigall-reverse.exp: reverse to handler of TERM (timeout) FAIL: gdb.reverse/sigall-reverse.exp: reverse to gen_TERM (timeout) This is another event-loop/async related problem exposed by the patch that made 'query' use gdb_readline_wrapper (588dcc3edbde19f9). The problem is that even though gdb_readline_wrapper disables target-async while the secondary prompt is in progress, the record target's async event source is left marked. So when gdb_readline_wrapper nests an event loop to process input, it may happen that that event loop ends up processing a target event while GDB is not really ready for it. Here's the relevant part of the backtrace showing the root issue in action: ... #14 0x000000000061cb48 in fetch_inferior_event (client_data=0x0) at src/gdb/infrun.c:4158 #15 0x0000000000642917 in inferior_event_handler (event_type=INF_REG_EVENT, client_data=0x0) at src/gdb/inf-loop.c:57 #16 0x000000000077ca5c in record_full_async_inferior_event_handler (data=0x0) at src/gdb/record-full.c:791 #17 0x0000000000640fdf in invoke_async_event_handler (data=...) at src/gdb/event-loop.c:1067 #18 0x000000000063fb01 in process_event () at src/gdb/event-loop.c:339 #19 0x000000000063fb2a in gdb_do_one_event () at src/gdb/event-loop.c:360 #20 0x000000000074d607 in gdb_readline_wrapper (prompt=0x3588f40 "The next instruction is syscall exit_group. It will make the program exit. Do you want to stop the program?([y] or n) ") at src/gdb/top.c:842 #21 0x0000000000750bd9 in defaulted_query (ctlstr=0x8c6588 "The next instruction is syscall exit_group. It will make the program exit. Do you want to stop the program?", defchar=121 'y', args=0x7fff70524410) at src/gdb/utils.c:1279 #22 0x0000000000750e4c in yquery (ctlstr=0x8c6588 "The next instruction is syscall exit_group. It will make the program exit. Do you want to stop the program?") at src/gdb/utils.c:1358 #23 0x00000000004b020e in record_linux_system_call (syscall=gdb_sys_exit_group, regcache=0x3529450, tdep=0xd6c840 ) at src/gdb/linux-record.c:1933 With my all-stop-on-top-of-non-stop series, I'm also seeing gdb.server/ext-attach.exp fail occasionally due to the same issue. The first part of the fix is for target_async implementations to make sure to remove/unmark all target-related event sources from the event loop. Tested on x86_64 Fedora 20, native and gdbserver. gdb/ 2015-02-03 Pedro Alves * event-loop.c (clear_async_event_handler): New function. * event-loop.h (clear_async_event_handler): New declaration. * record-btrace.c (record_btrace_async): New function. (init_record_btrace_ops): Install record_btrace_async. * record-full.c (record_full_async): New function. (record_full_resume): Don't mark the async event source here. (init_record_full_ops): Install record_full_async. (record_full_core_resume): Don't mark the async event source here. (init_record_full_core_ops): Install record_full_async. * remote.c (remote_async): Mark and clear the async stop reply queue event-loop token as appropriate. --- gdb/ChangeLog | 14 ++++++++++++++ gdb/event-loop.c | 8 ++++++++ gdb/event-loop.h | 4 ++++ gdb/record-btrace.c | 17 +++++++++++++++++ gdb/record-full.c | 32 ++++++++++++++++++++------------ gdb/remote.c | 10 +++++++++- 6 files changed, 72 insertions(+), 13 deletions(-) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index e7e60bb787d..9a36dc8276b 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,17 @@ +2015-02-03 Pedro Alves + + * event-loop.c (clear_async_event_handler): New function. + * event-loop.h (clear_async_event_handler): New declaration. + * record-btrace.c (record_btrace_async): New function. + (init_record_btrace_ops): Install record_btrace_async. + * record-full.c (record_full_async): New function. + (record_full_resume): Don't mark the async event source here. + (init_record_full_ops): Install record_full_async. + (record_full_core_resume): Don't mark the async event source here. + (init_record_full_core_ops): Install record_full_async. + * remote.c (remote_async): Mark and clear the async stop reply + queue event-loop token as appropriate. + 2015-02-03 Pedro Alves * linux-nat.c (linux_child_follow_fork, linux_nat_wait_1): Use diff --git a/gdb/event-loop.c b/gdb/event-loop.c index cfdd9a67162..e4de57265df 100644 --- a/gdb/event-loop.c +++ b/gdb/event-loop.c @@ -1050,6 +1050,14 @@ mark_async_event_handler (async_event_handler *async_handler_ptr) async_handler_ptr->ready = 1; } +/* See event-loop.h. */ + +void +clear_async_event_handler (async_event_handler *async_handler_ptr) +{ + async_handler_ptr->ready = 0; +} + struct async_event_handler_data { async_event_handler_func* proc; diff --git a/gdb/event-loop.h b/gdb/event-loop.h index feb5ea06961..b9338a2a47e 100644 --- a/gdb/event-loop.h +++ b/gdb/event-loop.h @@ -131,3 +131,7 @@ extern void /* Call the handler from HANDLER the next time through the event loop. */ extern void mark_async_event_handler (struct async_event_handler *handler); + +/* Mark the handler (ASYNC_HANDLER_PTR) as NOT ready. */ + +extern void clear_async_event_handler (struct async_event_handler *handler); diff --git a/gdb/record-btrace.c b/gdb/record-btrace.c index 3b7ef5ca5d0..7af549f33cd 100644 --- a/gdb/record-btrace.c +++ b/gdb/record-btrace.c @@ -266,6 +266,22 @@ record_btrace_close (struct target_ops *self) btrace_teardown (tp); } +/* The to_async method of target record-btrace. */ + +static void +record_btrace_async (struct target_ops *ops, + void (*callback) (enum inferior_event_type event_type, + void *context), + void *context) +{ + if (callback != NULL) + mark_async_event_handler (record_btrace_async_inferior_event_handler); + else + clear_async_event_handler (record_btrace_async_inferior_event_handler); + + ops->beneath->to_async (ops->beneath, callback, context); +} + /* The to_info_record method of target record-btrace. */ static void @@ -1940,6 +1956,7 @@ init_record_btrace_ops (void) ops->to_doc = "Collect control-flow trace and provide the execution history."; ops->to_open = record_btrace_open; ops->to_close = record_btrace_close; + ops->to_async = record_btrace_async; ops->to_detach = record_detach; ops->to_disconnect = record_disconnect; ops->to_mourn_inferior = record_mourn_inferior; diff --git a/gdb/record-full.c b/gdb/record-full.c index 6db16d6447b..c660743a407 100644 --- a/gdb/record-full.c +++ b/gdb/record-full.c @@ -910,6 +910,22 @@ record_full_close (struct target_ops *self) delete_async_event_handler (&record_full_async_inferior_event_token); } +/* "to_async" target method. */ + +static void +record_full_async (struct target_ops *ops, + void (*callback) (enum inferior_event_type event_type, + void *context), + void *context) +{ + if (callback != NULL) + mark_async_event_handler (record_full_async_inferior_event_token); + else + clear_async_event_handler (record_full_async_inferior_event_token); + + ops->beneath->to_async (ops->beneath, callback, context); +} + static int record_full_resume_step = 0; /* True if we've been resumed, and so each record_full_wait call should @@ -989,12 +1005,7 @@ record_full_resume (struct target_ops *ops, ptid_t ptid, int step, /* We are about to start executing the inferior (or simulate it), let's register it with the event loop. */ if (target_can_async_p ()) - { - target_async (inferior_event_handler, 0); - /* Notify the event loop there's an event to wait for. We do - most of the work in record_full_wait. */ - mark_async_event_handler (record_full_async_inferior_event_token); - } + target_async (inferior_event_handler, 0); } static int record_full_get_sig = 0; @@ -1902,6 +1913,7 @@ init_record_full_ops (void) "Log program while executing and replay execution from log."; record_full_ops.to_open = record_full_open; record_full_ops.to_close = record_full_close; + record_full_ops.to_async = record_full_async; record_full_ops.to_resume = record_full_resume; record_full_ops.to_wait = record_full_wait; record_full_ops.to_disconnect = record_disconnect; @@ -1943,12 +1955,7 @@ record_full_core_resume (struct target_ops *ops, ptid_t ptid, int step, /* We are about to start executing the inferior (or simulate it), let's register it with the event loop. */ if (target_can_async_p ()) - { - target_async (inferior_event_handler, 0); - - /* Notify the event loop there's an event to wait for. */ - mark_async_event_handler (record_full_async_inferior_event_token); - } + target_async (inferior_event_handler, 0); } /* "to_kill" method for prec over corefile. */ @@ -2141,6 +2148,7 @@ init_record_full_core_ops (void) "Log program while executing and replay execution from log."; record_full_core_ops.to_open = record_full_open; record_full_core_ops.to_close = record_full_close; + record_full_core_ops.to_async = record_full_async; record_full_core_ops.to_resume = record_full_core_resume; record_full_core_ops.to_wait = record_full_wait; record_full_core_ops.to_kill = record_full_core_kill; diff --git a/gdb/remote.c b/gdb/remote.c index 9be15cb3073..e971a29d51a 100644 --- a/gdb/remote.c +++ b/gdb/remote.c @@ -11691,9 +11691,17 @@ remote_async (struct target_ops *ops, serial_async (rs->remote_desc, remote_async_serial_handler, rs); rs->async_client_callback = callback; rs->async_client_context = context; + + /* If there are pending events in the stop reply queue tell the + event loop to process them. */ + if (!QUEUE_is_empty (stop_reply_p, stop_reply_queue)) + mark_async_event_handler (remote_async_inferior_event_token); } else - serial_async (rs->remote_desc, NULL, NULL); + { + serial_async (rs->remote_desc, NULL, NULL); + clear_async_event_handler (remote_async_inferior_event_token); + } } static void -- 2.30.2