[GIT PULL 6/9] intel_th: msu: Prevent freeing buffers while locked windows exist

[Alexander Shishkin <alexander.shishkin@linux.intel.com>]

We already prevent freeing buffers via sysfs interface in case there are
existing users or if trace is active. Treat the existence of locked windows
similarly and return -EBUSY on attempts to free the buffer. When the last
window is unlocked, the freeing will succeed.

Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 drivers/hwtracing/intel_th/msu.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/hwtracing/intel_th/msu.c b/drivers/hwtracing/intel_th/msu.c
index fc9890e56e5b..f2d52c025528 100644
--- a/drivers/hwtracing/intel_th/msu.c
+++ b/drivers/hwtracing/intel_th/msu.c
@@ -703,6 +703,11 @@ static int msc_win_set_lockout(struct msc_window *win, int expect, int new)
 	if (expect == WIN_LOCKED && old == new)
 		return 0;
 
+	if (old == expect && new == WIN_LOCKED)
+		atomic_inc(&win->msc->user_count);
+	else if (old == expect && old == WIN_LOCKED)
+		atomic_dec(&win->msc->user_count);
+
 	if (WARN_ONCE(old != expect, "expected lockout state %d, got %d\n",
 		      expect, old))
 		return -EINVAL;
-- 
2.20.1