linux-kernel - [PATCH 1/2] fsi: core: Lock scan mutex for master index removal

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Date:   Wed, 12 Apr 2023 13:56:01 -0500
From:   Eddie James <eajames@...ux.ibm.com>
To:     linux-fsi@...ts.ozlabs.org
Cc:     linux-kernel@...r.kernel.org, joel@....id.au, jk@...abs.org,
        alistair@...ple.id.au, Eddie James <eajames@...ux.ibm.com>
Subject: [PATCH 1/2] fsi: core: Lock scan mutex for master index removal

If a master scan occurs while the master is being unregistered,
the devicecs may end up with incorrect and possibly duplicate names,
resulting in kernel warnings. Ensure the master index isn't changed
outside of the scan mutex.

Signed-off-by: Eddie James <eajames@...ux.ibm.com>
---
 drivers/fsi/fsi-core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/fsi/fsi-core.c b/drivers/fsi/fsi-core.c
index fcbf0469ce3f..18d4d68482d7 100644
--- a/drivers/fsi/fsi-core.c
+++ b/drivers/fsi/fsi-core.c
@@ -1354,12 +1354,12 @@ EXPORT_SYMBOL_GPL(fsi_master_register);
 
 void fsi_master_unregister(struct fsi_master *master)
 {
+	mutex_lock(&master->scan_lock);
 	if (master->idx >= 0) {
 		ida_simple_remove(&master_ida, master->idx);
 		master->idx = -1;
 	}
 
-	mutex_lock(&master->scan_lock);
 	fsi_master_unscan(master);
 	mutex_unlock(&master->scan_lock);
 	device_unregister(&master->dev);
-- 
2.31.1