[for-next][PATCH 2/5] tracing/rb: Init the CPU mask on allocation

From: Steven Rostedt
Date: Tue Dec 13 2016 - 11:16:17 EST

From: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>

Before commit b32614c03413 ("tracing/rb: Convert to hotplug state
machine") the allocated cpumask was initialized to the mask of ONLINE or
POSSIBLE CPUs. After the CPU hotplug changes the buffer initialisation
moved to trace_rb_cpu_prepare() but I forgot to initially set the
cpumask to zero. This is done now.

Link: http://lkml.kernel.org/r/20161207133133.hzkcqfllxcdi3joz@xxxxxxxxxxxxx

Fixes: b32614c03413 ("tracing/rb: Convert to hotplug state machine")
Reported-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Tested-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
kernel/trace/ring_buffer.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index f17476f9d7f4..7edfd41d506c 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -1303,7 +1303,7 @@ struct ring_buffer *__ring_buffer_alloc(unsigned long size, unsigned flags,
if (!buffer)
return NULL;

- if (!alloc_cpumask_var(&buffer->cpumask, GFP_KERNEL))
+ if (!zalloc_cpumask_var(&buffer->cpumask, GFP_KERNEL))
goto fail_free_buffer;

nr_pages = DIV_ROUND_UP(size, BUF_PAGE_SIZE);