[tip:perf/core] perf/x86/intel/bts: Kill a silly warning

[tip-bot for Alexander Shishkin <tipbot@zytor.com>]

Commit-ID:  ef9ef3befa0d76008e988a9ed9fe439e803351b9
Gitweb:     http://git.kernel.org/tip/ef9ef3befa0d76008e988a9ed9fe439e803351b9
Author:     Alexander Shishkin <alexander.shishkin@linux.intel.com>
AuthorDate: Tue, 6 Sep 2016 16:23:53 +0300
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Sat, 10 Sep 2016 11:15:38 +0200

perf/x86/intel/bts: Kill a silly warning

At the moment, intel_bts will WARN() out if there is more than one
event writing to the same ring buffer, via SET_OUTPUT, and will only
send data from one event to a buffer.

There is no reason to have this warning in, so kill it.

Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: vince@deater.net
Link: http://lkml.kernel.org/r/20160906132353.19887-6-alexander.shishkin@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/events/intel/bts.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/arch/x86/events/intel/bts.c b/arch/x86/events/intel/bts.c
index 9233edf..bdcd651 100644
--- a/arch/x86/events/intel/bts.c
+++ b/arch/x86/events/intel/bts.c
@@ -378,8 +378,6 @@ bts_buffer_reset(struct bts_buffer *buf, struct perf_output_handle *handle)
 		return 0;
 
 	head = handle->head & ((buf->nr_pages << PAGE_SHIFT) - 1);
-	if (WARN_ON_ONCE(head != local_read(&buf->head)))
-		return -EINVAL;
 
 	phys = &buf->buf[buf->cur_buf];
 	space = phys->offset + phys->displacement + phys->size - head;