From 96fe2ab830d7dffee1b3d8abf27ced4d7d5765e7 Mon Sep 17 00:00:00 2001 From: Johannes Weiner Date: Tue, 10 Mar 2009 22:44:01 +0100 Subject: [PATCH] HID: fix waitqueue usage in hiddev DECLARE_WAITQUEUE doesn't initialize the wait descriptor's task_list to 'empty' but to zero. prepare_to_wait() will not enqueue the descriptor to the waitqueue and finish_wait() will do list_del_init() on a list head that contains NULL pointers, which oopses. This was introduced by 079034073 "HID: hiddev cleanup -- handle all error conditions properly". The prior code used an unconditional add_to_waitqueue() which didn't care about the wait descriptor's list head and enqueued the thing unconditionally. The new code uses prepare_to_wait() which DOES check the prior list state, so use DEFINE_WAIT instead. Signed-off-by: Johannes Weiner Cc: Oliver Neukum Cc: Jiri Kosina Signed-off-by: Andrew Morton Signed-off-by: Jiri Kosina --- drivers/hid/usbhid/hiddev.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/hid/usbhid/hiddev.c b/drivers/hid/usbhid/hiddev.c index 00ea1ed282a..1f5b5d4c3c3 100644 --- a/drivers/hid/usbhid/hiddev.c +++ b/drivers/hid/usbhid/hiddev.c @@ -323,7 +323,7 @@ static ssize_t hiddev_write(struct file * file, const char __user * buffer, size */ static ssize_t hiddev_read(struct file * file, char __user * buffer, size_t count, loff_t *ppos) { - DECLARE_WAITQUEUE(wait, current); + DEFINE_WAIT(wait); struct hiddev_list *list = file->private_data; int event_size; int retval; -- 2.41.1