From: Alan Cox <alan@lxorguk.ukuu.org.uk>

Signed-off-by: Alan Cox <alan@redhat.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---

 arch/sparc64/solaris/misc.c |    2 ++
 1 file changed, 2 insertions(+)

diff -puN arch/sparc64/solaris/misc.c~solaris-emulation-incorrect-tty-locking arch/sparc64/solaris/misc.c
--- a/arch/sparc64/solaris/misc.c~solaris-emulation-incorrect-tty-locking
+++ a/arch/sparc64/solaris/misc.c
@@ -422,7 +422,9 @@ asmlinkage int solaris_procids(int cmd, 
 			   Solaris setpgrp and setsid? */
 			ret = sys_setpgid(0, 0);
 			if (ret) return ret;
+			mutex_lock(&tty_mutex);
 			current->signal->tty = NULL;
+			mutex_unlock(&tty_mutex);
 			return process_group(current);
 		}
 	case 2: /* getsid */
_