[PATCH v1 4/5] intel_th: msu: Prevent freeing buffers while locked windows exist

[Alexander Shishkin]

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@xxxxxxxxxxxxxxx>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
---
 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 a6c0eb09c515..b200d9d1c7a0 100644
--- a/drivers/hwtracing/intel_th/msu.c
+++ b/drivers/hwtracing/intel_th/msu.c
@@ -724,6 +724,11 @@ static int msc_win_set_lockout(struct msc_window *win,
 
 	win->lockout = new;
 
+	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);
+
 unlock:
 	spin_unlock_irqrestore(&win->lo_lock, flags);
 
-- 
2.20.1