RFC: bsd_tcpip patch on synch.c

["Lambrecht Jürgen" <J.Lambrecht@TELEVIC.com>]

Hello,

The patch below we already use since 2009. But I did not code the patch, 
so I do not know what problem it solves. Here are our CVS logs about the 
patch:

- To avoid deadlock on mutex 'splx_mutex', I changed 'cyg_mutex_lock' 
into 'cyg_mutex_trylock'.
- Add 'trylock' and 'cyg_thread_delay' to spl_any() in order to handle 
the deadlock issue on the mutex 'splx_mutex'

I am applying the patches from Bernd Edlinger 
(http://bugs.ecos.sourceware.org/show_bug.cgi?id=1001656)(to fix an 
anoying problem "packet loss every 20 minutes when ARP timeout expires" 
and to add raw packets).
And I wonder if this patch (below) is still valid?
--------------------------------------------------------------------------------
Index: net/bsd_tcpip/current/src/ecos/synch.c
===================================================================
RCS file: /cvs/ecos/ecos-opt/net/net/bsd_tcpip/current/src/ecos/synch.c,v
retrieving revision 1.3
diff -u -5 -p -r1.3 synch.c
--- net/bsd_tcpip/current/src/ecos/synch.c      29 Jan 2009 17:49:56 
-0000      1.3
+++ net/bsd_tcpip/current/src/ecos/synch.c      27 Jun 2013 09:12:54 -0000
@@ -115,12 +115,14 @@ static volatile cyg_handle_t splx_thread
  static inline cyg_uint32
  spl_any( cyg_uint32 which )
  {
      cyg_uint32 old_spl = spl_state;
      if ( cyg_thread_self() != splx_thread ) {
-        while ( !cyg_mutex_lock( &splx_mutex ) )
+        while ( !cyg_mutex_trylock( &splx_mutex ) ) {
+          cyg_thread_delay(1);
              continue;
+        }
          old_spl = 0; // Free when we unlock this context
          CYG_ASSERT( 0 == splx_thread, "Thread still owned" );
          CYG_ASSERT( 0 == spl_state, "spl still set" );
          splx_thread = cyg_thread_self();
      }
--------------------------------------------------------------------------------
Kind regards,
Jürgen

-- 
Jürgen Lambrecht
R&D Associate
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