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Subject[PATCH] gigaset: call module_put before restart of if_open()
if_open() calls try_module_get(), and after an attempt to lock a mutex
the if_open() function may return -ERESTARTSYS without
putting the module. Then, when if_open() is executed again,
try_module_get() is called making the reference counter of THIS_MODULE
greater than one at successful exit from if_open(). The if_close()
function puts the module only once, and as a result it can't be

This patch adds module_put call before the return from if_open().

Found by Linux Driver Verification project (

Signed-off-by: Pavel Shved <>
drivers/isdn/gigaset/interface.c | 4 +++-
1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/drivers/isdn/gigaset/interface.c b/drivers/isdn/gigaset/interface.c
index 59de638..e35058b 100644
--- a/drivers/isdn/gigaset/interface.c
+++ b/drivers/isdn/gigaset/interface.c
@@ -156,8 +156,10 @@ static int if_open(struct tty_struct *tty, struct file *filp)
if (!cs || !try_module_get(cs->driver->owner))
return -ENODEV;

- if (mutex_lock_interruptible(&cs->mutex))
+ if (mutex_lock_interruptible(&cs->mutex)) {
+ module_put(cs->driver->owner);
+ }
tty->driver_data = cs;


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