tracing/rb: Init the CPU mask on allocation

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@linutronix.de
Fixes: b32614c03413 ("tracing/rb: Convert to hotplug state machine")
Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Tested-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index f17476f9d7f481a63361be2db73eefaaaaeed238..7edfd41d506c0e84245ada3e284bdc00d25e701e 100644 (file)
--- 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);