Gitweb:     http://git.kernel.org/linus/ca9fe1588427f246ad4c389b0170b29a432804b6
Commit:     ca9fe1588427f246ad4c389b0170b29a432804b6
Parent:     6e32819e12ffbd507eced11a1871700a387d5407
Author:     Julia Lawall <julia@diku.dk>
AuthorDate: Sun Jun 20 13:24:35 2010 +0200
Committer:  Jiri Kosina <jkosina@suse.cz>
CommitDate: Mon Jun 21 13:41:54 2010 +0200

    HID: eliminate a double lock in debug code
    
    The path around the loop ends with the lock held, so the call to mutex_lock
    is moved before the beginning of the loop.
    
    A simplified version of the semantic match that finds this problem is as
    follows: (http://coccinelle.lip6.fr/)
    
    // <smpl>
    @locked@
    expression E1;
    position p;
    @@
    
    read_lock(E1@p,...);
    
    @r exists@
    expression x <= locked.E1;
    expression locked.E1;
    expression E2;
    identifier lock;
    position locked.p,p1,p2;
    @@
    
    *lock@p1 (E1@p,...);
    ... when != E1
        when != \(x = E2\|&x\)
    *lock@p2 (E1,...);
    // </smpl>
    
    Signed-off-by: Julia Lawall <julia@diku.dk>
    Signed-off-by: Jiri Kosina <jkosina@suse.cz>
---
 drivers/hid/hid-debug.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/hid/hid-debug.c b/drivers/hid/hid-debug.c
index c940267..850d02a 100644
--- a/drivers/hid/hid-debug.c
+++ b/drivers/hid/hid-debug.c
@@ -949,8 +949,8 @@ static ssize_t hid_debug_events_read(struct file *file, char __user *buffer,
 	int ret = 0, len;
 	DECLARE_WAITQUEUE(wait, current);
 
+	mutex_lock(&list->read_mutex);
 	while (ret == 0) {
-		mutex_lock(&list->read_mutex);
 		if (list->head == list->tail) {
 			add_wait_queue(&list->hdev->debug_wait, &wait);
 			set_current_state(TASK_INTERRUPTIBLE);
--
To unsubscribe from this list: send the line "unsubscribe git-commits-head" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html