[PATCH] Relay: add CPU hotplug support

Mathieu originally needed to add this for tracing Xen, but it's something
that's needed for any application that can be tracing while cpus are added.

unplug isn't supported by this patch.  The thought was that at minumum a new
buffer needs to be added when a cpu comes up, but it wasn't worth the effort
to remove buffers on cpu down since they'd be freed soon anyway when the
channel was closed.

[zanussi@us.ibm.com: avoid lock_cpu_hotplug deadlock]
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Tom Zanussi <zanussi@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 2 deletions

diff --git a/block/blktrace.c b/block/blktrace.c
index d3679dd1d22..d36b32ed22f 100644
--- a/block/blktrace.c
+++ b/block/blktrace.c
@@ -363,10 +363,9 @@ static int blk_trace_setup(request_queue_t *q, struct block_device *bdev,
         if (!bt->dropped_file)
                 goto err;
 
-        bt->rchan = relay_open("trace", dir, buts.buf_size, buts.buf_nr, &blk_relay_callbacks);
+        bt->rchan = relay_open("trace", dir, buts.buf_size, buts.buf_nr, &blk_relay_callbacks, bt);
         if (!bt->rchan)
                 goto err;
-        bt->rchan->private_data = bt;
 
         bt->act_mask = buts.act_mask;
         if (!bt->act_mask)