The patch titled
hci_usb: replace mb with smp_mb
has been added to the -mm tree. Its filename is
hci_usb-replace-mb-with-smp_mb.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: hci_usb: replace mb with smp_mb
From: Ming Lei <tom.leiming@xxxxxxxxx>
smp_mb is enough for ordering memory operations among processors,and mb is
more expensive than smp_mb for UP machine, so replace it with smp_mb().
Signed-off-by: Ming Lei <tom.leiming@xxxxxxxxx>
Cc: Marcel Holtmann <marcel@xxxxxxxxxxxx>
Cc: Dave Young <hidave.darkstar@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/bluetooth/hci_usb.h | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff -puN drivers/bluetooth/hci_usb.h~hci_usb-replace-mb-with-smp_mb drivers/bluetooth/hci_usb.h
--- a/drivers/bluetooth/hci_usb.h~hci_usb-replace-mb-with-smp_mb
+++ a/drivers/bluetooth/hci_usb.h
@@ -70,8 +70,8 @@ static inline void _urb_queue_head(struc
{
unsigned long flags;
spin_lock_irqsave(&q->lock, flags);
- /* _urb_unlink needs to know which spinlock to use, thus mb(). */
- _urb->queue = q; mb(); list_add(&_urb->list, &q->head);
+ /* _urb_unlink needs to know which spinlock to use, thus smp_mb(). */
+ _urb->queue = q; smp_mb(); list_add(&_urb->list, &q->head);
spin_unlock_irqrestore(&q->lock, flags);
}
@@ -79,8 +79,8 @@ static inline void _urb_queue_tail(struc
{
unsigned long flags;
spin_lock_irqsave(&q->lock, flags);
- /* _urb_unlink needs to know which spinlock to use, thus mb(). */
- _urb->queue = q; mb(); list_add_tail(&_urb->list, &q->head);
+ /* _urb_unlink needs to know which spinlock to use, thus smp_mb(). */
+ _urb->queue = q; smp_mb(); list_add_tail(&_urb->list, &q->head);
spin_unlock_irqrestore(&q->lock, flags);
}
@@ -89,7 +89,7 @@ static inline void _urb_unlink(struct _u
struct _urb_queue *q;
unsigned long flags;
- mb();
+ smp_mb();
q = _urb->queue;
/* If q is NULL, it will die at easy-to-debug NULL pointer dereference.
No need to BUG(). */
_
Patches currently in -mm which might be from tom.leiming@xxxxxxxxx are
hci_usb-replace-mb-with-smp_mb.patch
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