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chardev: fix backend events regression with mux chardev

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Kirill noticied that on recent versions on QEMU he was not able to
trigger SysRq to invoke debug capabilites of Linux Kernel.  He tracked
it down to qemu_chr_be_event() ignoring CHR_EVENT_BREAK due s->be
being NULL. The bug was introduced in 2.8, commit a4afa548fc ("char:
move front end handlers in CharBackend"). Since the commit, the
qemu_chr_be_event() failed to deliver CHR_EVENT_BREAK due to
qemu_chr_fe_init() does not set s->be in case of mux.

Let's fix this by teaching mux to send an event to the frontend with
the focus.

Reported-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Fixes: a4afa548fc ("char: move front end handlers in CharBackend")
Message-Id: <20171103152824.21948-2-marcandre.lureau@redhat.com>
Tested-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Marc-André Lureau 2017-11-03 16:28:23 +01:00 • committed by Paolo Bonzini
parent 5a22ab7162
commit d09c4a4787
3 changed files with 23 additions and 6 deletions
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10
chardev/char-mux.c
View file

@ -123,6 +123,15 @@ static void mux_chr_send_event(MuxChardev *d, int mux_nr, int event)
}
}
static void mux_chr_be_event(Chardev *chr, int event)
{
MuxChardev *d = MUX_CHARDEV(chr);
if (d->focus != -1) {
mux_chr_send_event(d, d->focus, event);
}
}
static int mux_proc_byte(Chardev *chr, MuxChardev *d, int ch)
{
if (d->term_got_escape) {
@ -346,6 +355,7 @@ static void char_mux_class_init(ObjectClass *oc, void *data)
cc->chr_write = mux_chr_write;
cc->chr_accept_input = mux_chr_accept_input;
cc->chr_add_watch = mux_chr_add_watch;
cc->chr_be_event = mux_chr_be_event;
}
static const TypeInfo char_mux_type_info = {