intel_th: msu: Prevent freeing buffers while locked windows exist

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>
Link: https://lore.kernel.org/r/20190705141425.19894-5-alexander.shishkin@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/hwtracing/intel_th/msu.c b/drivers/hwtracing/intel_th/msu.c
index a6c0eb09c515893dcb8c1725cb3c34a961f60eb7..b200d9d1c7a0383426b7ce7b8a93ef1f56519d5e 100644 (file)
--- 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);