From: Todd Poynor <toddpoy...@google.com>

Keep mutex held across the unregistration operation, until the
driver_desc field of the global table is removed, to prevent a
concurrent accessor from looking up the driver_desc while
gasket_unregister_device() is in the processing of removing it.

Reported-by: Guenter Roeck <gro...@chromium.org>
Signed-off-by: Todd Poynor <toddpoy...@google.com>
---
 drivers/staging/gasket/gasket_core.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/staging/gasket/gasket_core.c 
b/drivers/staging/gasket/gasket_core.c
index ace92f107ed58..a6462b6d702f1 100644
--- a/drivers/staging/gasket/gasket_core.c
+++ b/drivers/staging/gasket/gasket_core.c
@@ -1765,9 +1765,9 @@ void gasket_unregister_device(const struct 
gasket_driver_desc *driver_desc)
                        break;
                }
        }
-       mutex_unlock(&g_mutex);
 
        if (!internal_desc) {
+               mutex_unlock(&g_mutex);
                pr_err("request to unregister unknown desc: %s, %d:%d\n",
                       driver_desc->name, driver_desc->major,
                       driver_desc->minor);
@@ -1780,7 +1780,6 @@ void gasket_unregister_device(const struct 
gasket_driver_desc *driver_desc)
        class_destroy(internal_desc->class);
 
        /* Finally, effectively "remove" the driver. */
-       mutex_lock(&g_mutex);
        g_descs[desc_idx].driver_desc = NULL;
        mutex_unlock(&g_mutex);
 
-- 
2.18.0.597.ga71716f1ad-goog

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