[PATCH] mshv_vtl: initialize poll file mutex before device registration

[Jiale Yao]

mshv_vtl_init() registers /dev/mshv before initializing the poll file
mutex. A concurrent MSHV_SET_POLL_FILE ioctl can therefore attempt to lock
an uninitialized mutex while module initialization is still in progress.

Initialize the file-scope mutex statically so it is ready before the misc
device becomes visible.

Fixes: 7bfe3b8ea6e3 ("Drivers: hv: Introduce mshv_vtl driver")
Signed-off-by: Jiale Yao <yaojial...@163.com>
---
 drivers/hv/mshv_vtl_main.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/hv/mshv_vtl_main.c b/drivers/hv/mshv_vtl_main.c
index d8225242c73f..2b40c9e3bf88 100644
--- a/drivers/hv/mshv_vtl_main.c
+++ b/drivers/hv/mshv_vtl_main.c
@@ -95,7 +95,7 @@ union hv_synic_overlay_page_msr {
        } __packed;
 };
 
-static struct mutex mshv_vtl_poll_file_lock;
+static DEFINE_MUTEX(mshv_vtl_poll_file_lock);
 static union hv_register_vsm_page_offsets mshv_vsm_page_offsets;
 static union hv_register_vsm_capabilities mshv_vsm_capabilities;
 
@@ -1370,8 +1370,6 @@ static int __init mshv_vtl_init(void)
                goto free_low;
        }
 
-       mutex_init(&mshv_vtl_poll_file_lock);
-
        device_initialize(mem_dev);
        dev_set_name(mem_dev, "mshv vtl mem dev");
        ret = device_add(mem_dev);
-- 
2.34.1