From b2ee242b93e9580406e03abb18ff969de7de1976 Mon Sep 17 00:00:00 2001 From: Pedro Alves Date: Mon, 7 Jul 2014 17:51:04 +0100 Subject: [PATCH] PR gdb/17096: async support breaks remote debugging on Windows On Windows, with "maint set target-async on" (the default since a09dd441), Ctrl-C fails to stop a remote target. With maint target-async on, the SIGINT signal handler doesn't send the remote interrupt request immediately. Instead, it marks an async handler as ready, and then the main event loop wakes up and notices that the SIGINT async signal handler token was set, and calls the corresponding event handler, which sends the remote interrupt request. On POSIX-like systems, the SIGINT signal makes the select/poll in the main event loop wake up / return with EINTR. However, on Windows, signal handlers run on a separate thread, and Windows doesn't really have a concept of EINTR. So, just marking the async handler (effectively just setting a flag) does not wake up gdb_select. Instead, we need to call gdb_call_async_signal_handler from the signal handler. The Windows version (in mingw-hdep.c) sets a Windows event that gdb_select's WaitForMultipleObjects is waiting for. Confirmed that with this, Ctrl-C interrupts the remote target on Windows. Also regression tested on x86_64 Fedora 20 against GDBserver. gdb/ 2014-07-07 Pedro Alves * remote.c (async_handle_remote_sigint) (async_handle_remote_sigint_twice): Call gdb_call_async_signal_handler instead of mark_async_signal_handler. --- gdb/ChangeLog | 7 +++++++ gdb/remote.c | 7 +++++-- 2 files changed, 12 insertions(+), 2 deletions(-) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index f41451a..f2e6450 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,10 @@ +2014-07-07 Pedro Alves + + * remote.c (async_handle_remote_sigint) + (async_handle_remote_sigint_twice): Call + gdb_call_async_signal_handler instead of + mark_async_signal_handler. + 2014-07-07 Tom Tromey * target-delegates.c: Rebuild. diff --git a/gdb/remote.c b/gdb/remote.c index b6f3ddb..3aa030c 100644 --- a/gdb/remote.c +++ b/gdb/remote.c @@ -4818,7 +4818,9 @@ static void async_handle_remote_sigint (int sig) { signal (sig, async_handle_remote_sigint_twice); - mark_async_signal_handler (async_sigint_remote_token); + /* Note we need to go through gdb_call_async_signal_handler in order + to wake up the event loop on Windows. */ + gdb_call_async_signal_handler (async_sigint_remote_token, 0); } /* Signal handler for SIGINT, installed after SIGINT has already been @@ -4828,7 +4830,8 @@ static void async_handle_remote_sigint_twice (int sig) { signal (sig, async_handle_remote_sigint); - mark_async_signal_handler (async_sigint_remote_twice_token); + /* See note in async_handle_remote_sigint. */ + gdb_call_async_signal_handler (async_sigint_remote_twice_token, 0); } /* Perform the real interruption of the target execution, in response -- 2.7.4