[PATCH 018/149] USB: ehci refcounts work on ppc7448
Greg Kroah-Hartman <[email protected]>
| Newsgroups | gmane.linux.usb.devel |
|---|---|
| Message-ID | <[email protected]> |
From: David Brownell <[email protected]> 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; -- 1.5.2.2 ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ [email protected] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel