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

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Message-Id: <20190627125152.54905-7-alexander.shishkin@linux.intel.com>
Date:   Thu, 27 Jun 2019 15:51:49 +0300
From:   Alexander Shishkin <alexander.shishkin@...ux.intel.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-kernel@...r.kernel.org,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Subject: [GIT PULL 6/9] 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@...ux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@...ux.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