Maybe the block signal should just be removed? As I understand, any existing code trying to use this will just start throwing g_criticals instead of locking up the pipeline, so that's okay.

Created attachment 290971 [details] [review]
patch removes signal

[PATCH] input-selector: Remove obsolete 'block' signal

This signal blocks the input-selector with no means of unblocking
other than a state change back to READY. Seems it was part of an
old way of switching together with the already-removed 'switch'
signal.

Please review the patch.

Review of attachment 290971 [details] [review]:

Seems almost ok, but please add some explanation in the commit message *why* it is ok to drop the signal. (Nobody could've used it for anything different than causing deadlocks)

::: plugins/elements/gstinputselector.c
@@ -960,3 @@
   GST_INPUT_SELECTOR_LOCK (sel);
-  /* wait or check for flushing */
-  if (gst_input_selector_wait (sel, selpad)) {

wait() actually *waited* for self->flushing or pad->flushing (or not blocking). This changes behaviour I think

(In reply to Sebastian Dröge (slomo) from comment #4)

> wait() actually *waited* for self->flushing or pad->flushing (or not 
blocking). This changes behaviour I think

Actually, no. Without the signal, self->blocked cannot ever be TRUE. Accordingly, gst_input_selector_wait will never wait and just return self->flushing.

Created attachment 300128 [details] [review]
patch 1/2

This is now on top of the patch from bug 746518.

Created attachment 300129 [details] [review]
patch 2/2

Thanks for the patches, fixed.

commit 0a3ded193278ad95b04ace3dc5e2fcf7e277abff
Author: Jan Alexander Steffens (heftig) <jsteffens@make.tv>
Date:   Mon Mar 23 13:20:34 2015 +0100

    input-selector: Remove 'blocked' flag
    
    With the disappearance of the 'block' signal, this
    flag cannot be set to TRUE.
    
    gst_input_selector_wait disappears as it never waits
    and just returns self->flushing.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=736891

commit 7a1ebbe0e3a19c4e2108ddbb50095add3d265d9d
Author: Jan Alexander Steffens (heftig) <jsteffens@make.tv>
Date:   Mon Mar 23 12:12:51 2015 +0100

    input-selector: Remove obsolete 'block' signal
    
    This signal blocks the input-selector with no means of unblocking
    other than a state change back to READY. It seems this signal was
    part of an old way of synchronously switching the selector,
    together with the already-removed 'switch' signal.
    
    Removing the signal is safe, as attempting to use it could only
    end in deadlocks. Attempting to emit an unknown signal just causes
    g_criticals.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=736891