[Bug gdb/17096] async support breaks remote debugging on Windows

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https://sourceware.org/bugzilla/show_bug.cgi?id=17096

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https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=5bbc46815600d34fe7e5f3b8cda4bad0a70e95ad

commit 5bbc46815600d34fe7e5f3b8cda4bad0a70e95ad
Author: Pedro Alves <palves@redhat.com>
Date:   Mon Jul 7 19:06:35 2014 +0100

    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  <palves@redhat.com>

        gdb/17096
        * remote.c (async_handle_remote_sigint)
        (async_handle_remote_sigint_twice): Call
        gdb_call_async_signal_handler instead of
        mark_async_signal_handler.

-----------------------------------------------------------------------

Summary of changes:
 gdb/ChangeLog |    8 ++++++++
 gdb/remote.c  |    7 +++++--
 2 files changed, 13 insertions(+), 2 deletions(-)

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