Try reverting:

commit e43abdce964f5ed9689cf908af8c305b39a5dd36
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date:   Wed Feb 3 09:54:46 2016 +0000

    dri2: Unblock Clients on Drawable release

And please try:

diff --git a/dix/dispatch.c b/dix/dispatch.c
index 53032dc..6257369 100644
--- a/dix/dispatch.c
+++ b/dix/dispatch.c
@@ -3414,6 +3414,8 @@ CloseDownClient(ClientPtr client)
     }
 
     if (really_close_down) {
+        client->ignoreCount++;
+
         if (client->clientState == ClientStateRunning && nClients == 0)
             dispatchException |= dispatchExceptionAtReset;

(In reply to Chris Wilson from comment #2)
> And please try:
> 
> diff --git a/dix/dispatch.c b/dix/dispatch.c
> index 53032dc..6257369 100644
> --- a/dix/dispatch.c
> +++ b/dix/dispatch.c
> @@ -3414,6 +3414,8 @@ CloseDownClient(ClientPtr client)
>      }
>  
>      if (really_close_down) {
> +        client->ignoreCount++;
> +
>          if (client->clientState == ClientStateRunning && nClients == 0)
>              dispatchException |= dispatchExceptionAtReset;

At your request I added 'client->ignoreCount++;' in /dix/dispatch.c
but after make install and new login I still get the same segmentation fault.

Hmm, I think you also need

diff --git a/os/connection.c b/os/connection.c
index 4c1ba4b..0a7056f 100644
--- a/os/connection.c
+++ b/os/connection.c
@@ -1291,12 +1291,13 @@ void
 AttendClient(ClientPtr client)
 {
     OsCommPtr oc = (OsCommPtr) client->osPrivate;
-    int connection = oc->fd;
+    int connection;
 
     client->ignoreCount--;
     if (client->ignoreCount)
         return;
 
+    connection = oc->fd;
     if (!GrabInProgress || GrabInProgress == client->index ||
         FD_ISSET(connection, &GrabImperviousClients)) {
         FD_SET(connection, &AllClients);

as well as the previous dix/dispatch.c chunk

(In reply to Chris Wilson from comment #4)
> Hmm, I think you also need
> 
> diff --git a/os/connection.c b/os/connection.c
> index 4c1ba4b..0a7056f 100644
> --- a/os/connection.c
> +++ b/os/connection.c
> @@ -1291,12 +1291,13 @@ void
>  AttendClient(ClientPtr client)
>  {
>      OsCommPtr oc = (OsCommPtr) client->osPrivate;
> -    int connection = oc->fd;
> +    int connection;
>  
>      client->ignoreCount--;
>      if (client->ignoreCount)
>          return;
>  
> +    connection = oc->fd;
>      if (!GrabInProgress || GrabInProgress == client->index ||
>          FD_ISSET(connection, &GrabImperviousClients)) {
>          FD_SET(connection, &AllClients);
> 
> as well as the previous dix/dispatch.c chunk

You'r right, I applied your patches and this bug is fixed, thanks!

Successfully reproduced using XKillClient.

https://patchwork.freedesktop.org/patch/73115/
https://patchwork.freedesktop.org/patch/73116/

commit eddf848c44349c7ebc7da9957bffb3630f3faaa9
Author: Adam Jackson <ajax@redhat.com>
Date:   Wed Feb 10 11:13:04 2016 -0500

    dri2: Use the work queue to manage client sleeps