From 77078570abe0848c3076b4f7d42f79b1407f3e8f Mon Sep 17 00:00:00 2001 From: David Brownell Date: Sat, 28 May 2005 10:46:18 -0700 Subject: [PATCH] [PATCH] USB: ehci-hcd - fix page pointer allocation in itd_patch() The itd_patch() function is responsible for allocating entries in the buffer page pointer list of the iTD. Particularly, a new page pointer is needed every time when buffer data crosses a page boundary. However, there is a bug in the allocation logic: the function does not allocate a new entry when the current transaction is the first transaction in the iTD (as indicated by first!=0). The consequence is that, when the data of the first transaction begins somewhere at the end of a page so that it actually does cross the page boundary, no new page pointer is allocated. This means that the data at the end of the first transaction (beyond the page boundary) will be accessed by the HC using the second page pointer, which is zero. Furthermore, the first page pointer will be later overwritten by the page pointers of the other transactions, which will garble it because the value is or-ed into the iTD field. All this particular check (for !first) does is cause incorrect behaviour, so it should be entirely removed (and with it the variable first that is not used for anything else). Signed-off-by: Clemens Ladisch Signed-off-by: David Brownell Signed-off-by: Greg Kroah-Hartman --- drivers/usb/host/ehci-sched.c | 17 +++++++---------- 1 file changed, 7 insertions(+), 10 deletions(-) diff --git a/drivers/usb/host/ehci-sched.c b/drivers/usb/host/ehci-sched.c index 2fa1ffee5ff3..c2104cad4033 100644 --- a/drivers/usb/host/ehci-sched.c +++ b/drivers/usb/host/ehci-sched.c @@ -637,9 +637,8 @@ iso_stream_alloc (int mem_flags) { struct ehci_iso_stream *stream; - stream = kmalloc(sizeof *stream, mem_flags); + stream = kcalloc(1, sizeof *stream, mem_flags); if (likely (stream != NULL)) { - memset (stream, 0, sizeof(*stream)); INIT_LIST_HEAD(&stream->td_list); INIT_LIST_HEAD(&stream->free_list); stream->next_uframe = -1; @@ -894,7 +893,7 @@ itd_sched_init ( trans |= length << 16; uframe->transaction = cpu_to_le32 (trans); - /* might need to cross a buffer page within a td */ + /* might need to cross a buffer page within a uframe */ uframe->bufp = (buf & ~(u64)0x0fff); buf += length; if (unlikely ((uframe->bufp != (buf & ~(u64)0x0fff)))) @@ -1194,6 +1193,7 @@ itd_init (struct ehci_iso_stream *stream, struct ehci_itd *itd) { int i; + /* it's been recently zeroed */ itd->hw_next = EHCI_LIST_END; itd->hw_bufp [0] = stream->buf0; itd->hw_bufp [1] = stream->buf1; @@ -1210,8 +1210,7 @@ itd_patch ( struct ehci_itd *itd, struct ehci_iso_sched *iso_sched, unsigned index, - u16 uframe, - int first + u16 uframe ) { struct ehci_iso_packet *uf = &iso_sched->packet [index]; @@ -1228,7 +1227,7 @@ itd_patch ( itd->hw_bufp_hi [pg] |= cpu_to_le32 ((u32)(uf->bufp >> 32)); /* iso_frame_desc[].offset must be strictly increasing */ - if (unlikely (!first && uf->cross)) { + if (unlikely (uf->cross)) { u64 bufp = uf->bufp + 4096; itd->pg = ++pg; itd->hw_bufp [pg] |= cpu_to_le32 (bufp & ~(u32)0); @@ -1257,7 +1256,7 @@ itd_link_urb ( struct ehci_iso_stream *stream ) { - int packet, first = 1; + int packet; unsigned next_uframe, uframe, frame; struct ehci_iso_sched *iso_sched = urb->hcpriv; struct ehci_itd *itd; @@ -1290,7 +1289,6 @@ itd_link_urb ( list_move_tail (&itd->itd_list, &stream->td_list); itd->stream = iso_stream_get (stream); itd->urb = usb_get_urb (urb); - first = 1; itd_init (stream, itd); } @@ -1298,8 +1296,7 @@ itd_link_urb ( frame = next_uframe >> 3; itd->usecs [uframe] = stream->usecs; - itd_patch (itd, iso_sched, packet, uframe, first); - first = 0; + itd_patch (itd, iso_sched, packet, uframe); next_uframe += stream->interval; stream->depth += stream->interval; -- 2.20.1