Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=9c033e810eef0aff6d4d3bf028aa1e583c074f93
Commit: 9c033e810eef0aff6d4d3bf028aa1e583c074f93
Parent: 04d06ad0f1fdb499af84ae3d7969e2136a462f38
Author: David Brownell <[EMAIL PROTECTED]>
AuthorDate: Thu May 17 12:21:19 2007 -0700
Committer: Greg Kroah-Hartman <[EMAIL PROTECTED]>
CommitDate: Thu Jul 12 16:29:47 2007 -0700
USB: ehci refcounts work on ppc7448
Remove atomic operations on the reference counter for EHCI queue heads.
On various platforms (including ppc7448), atomic operations are unusable
with dma-coherent memory.
Signed-off-by: Steven J. Hill <[EMAIL PROTECTED]>
Signed-off-by: David Brownell <[EMAIL PROTECTED]>
Signed-off-by: Greg Kroah-Hartman <[EMAIL PROTECTED]>
---
drivers/usb/host/ehci-mem.c | 11 ++++++-----
drivers/usb/host/ehci.h | 9 ++++++++-
2 files changed, 14 insertions(+), 6 deletions(-)
diff --git a/drivers/usb/host/ehci-mem.c b/drivers/usb/host/ehci-mem.c
index bdb29e6..8816d09 100644
--- a/drivers/usb/host/ehci-mem.c
+++ b/drivers/usb/host/ehci-mem.c
@@ -64,9 +64,8 @@ static inline void ehci_qtd_free (struct ehci_hcd *ehci,
struct ehci_qtd *qtd)
}
-static void qh_destroy (struct kref *kref)
+static void qh_destroy(struct ehci_qh *qh)
{
- struct ehci_qh *qh = container_of(kref, struct ehci_qh, kref);
struct ehci_hcd *ehci = qh->ehci;
/* clean qtds first, and know this is not linked */
@@ -90,7 +89,7 @@ static struct ehci_qh *ehci_qh_alloc (struct ehci_hcd *ehci,
gfp_t flags)
return qh;
memset (qh, 0, sizeof *qh);
- kref_init(&qh->kref);
+ qh->refcount = 1;
qh->ehci = ehci;
qh->qh_dma = dma;
// INIT_LIST_HEAD (&qh->qh_list);
@@ -112,13 +111,15 @@ static struct ehci_qh *ehci_qh_alloc (struct ehci_hcd
*ehci, gfp_t flags)
/* to share a qh (cpu threads, or hc) */
static inline struct ehci_qh *qh_get (struct ehci_qh *qh)
{
- kref_get(&qh->kref);
+ WARN_ON(!qh->refcount);
+ qh->refcount++;
return qh;
}
static inline void qh_put (struct ehci_qh *qh)
{
- kref_put(&qh->kref, qh_destroy);
+ if (!--qh->refcount)
+ qh_destroy(qh);
}
/*-------------------------------------------------------------------------*/
diff --git a/drivers/usb/host/ehci.h b/drivers/usb/host/ehci.h
index 79ad2af..6ef9d77 100644
--- a/drivers/usb/host/ehci.h
+++ b/drivers/usb/host/ehci.h
@@ -457,7 +457,14 @@ struct ehci_qh {
struct ehci_qh *reclaim; /* next to reclaim */
struct ehci_hcd *ehci;
- struct kref kref;
+
+ /*
+ * Do NOT use atomic operations for QH refcounting. On some CPUs
+ * (PPC7448 for example), atomic operations cannot be performed on
+ * memory that is cache-inhibited (i.e. being used for DMA).
+ * Spinlocks are used to protect all QH fields.
+ */
+ u32 refcount;
unsigned stamp;
u8 qh_state;
-
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