Acquire the send socket buffer lock around tcp_output() activities reaching into the socket buffer.  This prevents a number of potential races, including dereferencing of sb_mb while unlocked leading to a NULL pointer deref (how I found it).  Potentially this might also explain other "odd" TCP behavior on SMP boxes (although  haven't seen it reported).
Acquire the send socket buffer lock around tcp_output() activities
reaching into the socket buffer.  This prevents a number of potential
races, including dereferencing of sb_mb while unlocked leading to
a NULL pointer deref (how I found it).  Potentially this might also
explain other "odd" TCP behavior on SMP boxes (although  haven't
seen it reported).

RELENG_5 candidate.

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase