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Subject[42/49] usb: fix number of mapped SG DMA entries
3.2-stable review patch.  If anyone has any objections, please let me know.

------------------
From: Clemens Ladisch <clemens@ladisch.de>

commit bc677d5b64644c399cd3db6a905453e611f402ab upstream.

Add a new field num_mapped_sgs to struct urb so that we have a place to
store the number of mapped entries and can also retain the original
value of entries in num_sgs. Previously, usb_hcd_map_urb_for_dma()
would overwrite this with the number of mapped entries, which would
break dma_unmap_sg() because it requires the original number of entries.

This fixes warnings like the following when using USB storage devices:
------------[ cut here ]------------
WARNING: at lib/dma-debug.c:902 check_unmap+0x4e4/0x695()
ehci_hcd 0000:00:12.2: DMA-API: device driver frees DMA sg list with different entry count [map count=4] [unmap count=1]
Modules linked in: ohci_hcd ehci_hcd
Pid: 0, comm: kworker/0:1 Not tainted 3.2.0-rc2+ #319
Call Trace:
<IRQ> [<ffffffff81036d3b>] warn_slowpath_common+0x80/0x98
[<ffffffff81036de7>] warn_slowpath_fmt+0x41/0x43
[<ffffffff811fa5ae>] check_unmap+0x4e4/0x695
[<ffffffff8105e92c>] ? trace_hardirqs_off+0xd/0xf
[<ffffffff8147208b>] ? _raw_spin_unlock_irqrestore+0x33/0x50
[<ffffffff811fa84a>] debug_dma_unmap_sg+0xeb/0x117
[<ffffffff8137b02f>] usb_hcd_unmap_urb_for_dma+0x71/0x188
[<ffffffff8137b166>] unmap_urb_for_dma+0x20/0x22
[<ffffffff8137b1c5>] usb_hcd_giveback_urb+0x5d/0xc0
[<ffffffffa0000d02>] ehci_urb_done+0xf7/0x10c [ehci_hcd]
[<ffffffffa0001140>] qh_completions+0x429/0x4bd [ehci_hcd]
[<ffffffffa000340a>] ehci_work+0x95/0x9c0 [ehci_hcd]
...
---[ end trace f29ac88a5a48c580 ]---
Mapped at:
[<ffffffff811faac4>] debug_dma_map_sg+0x45/0x139
[<ffffffff8137bc0b>] usb_hcd_map_urb_for_dma+0x22e/0x478
[<ffffffff8137c494>] usb_hcd_submit_urb+0x63f/0x6fa
[<ffffffff8137d01c>] usb_submit_urb+0x2c7/0x2de
[<ffffffff8137dcd4>] usb_sg_wait+0x55/0x161
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/usb/core/hcd.c | 5 ++---
drivers/usb/host/ehci-q.c | 2 +-
drivers/usb/host/uhci-q.c | 2 +-
drivers/usb/host/whci/qset.c | 4 ++--
drivers/usb/host/xhci-ring.c | 4 ++--
include/linux/usb.h | 1 +
6 files changed, 9 insertions(+), 9 deletions(-)
--- a/drivers/usb/core/hcd.c
+++ b/drivers/usb/core/hcd.c
@@ -1412,11 +1412,10 @@ int usb_hcd_map_urb_for_dma(struct usb_h
ret = -EAGAIN;
else
urb->transfer_flags |= URB_DMA_MAP_SG;
- if (n != urb->num_sgs) {
- urb->num_sgs = n;
+ urb->num_mapped_sgs = n;
+ if (n != urb->num_sgs)
urb->transfer_flags |=
URB_DMA_SG_COMBINED;
- }
} else if (urb->sg) {
struct scatterlist *sg = urb->sg;
urb->transfer_dma = dma_map_page(
--- a/drivers/usb/host/ehci-q.c
+++ b/drivers/usb/host/ehci-q.c
@@ -647,7 +647,7 @@ qh_urb_transaction (
/*
* data transfer stage: buffer setup
*/
- i = urb->num_sgs;
+ i = urb->num_mapped_sgs;
if (len > 0 && i > 0) {
sg = urb->sg;
buf = sg_dma_address(sg);
--- a/drivers/usb/host/uhci-q.c
+++ b/drivers/usb/host/uhci-q.c
@@ -943,7 +943,7 @@ static int uhci_submit_common(struct uhc
if (usb_pipein(urb->pipe))
status |= TD_CTRL_SPD;

- i = urb->num_sgs;
+ i = urb->num_mapped_sgs;
if (len > 0 && i > 0) {
sg = urb->sg;
data = sg_dma_address(sg);
--- a/drivers/usb/host/whci/qset.c
+++ b/drivers/usb/host/whci/qset.c
@@ -443,7 +443,7 @@ static int qset_add_urb_sg(struct whc *w

remaining = urb->transfer_buffer_length;

- for_each_sg(urb->sg, sg, urb->num_sgs, i) {
+ for_each_sg(urb->sg, sg, urb->num_mapped_sgs, i) {
dma_addr_t dma_addr;
size_t dma_remaining;
dma_addr_t sp, ep;
@@ -561,7 +561,7 @@ static int qset_add_urb_sg_linearize(str

remaining = urb->transfer_buffer_length;

- for_each_sg(urb->sg, sg, urb->num_sgs, i) {
+ for_each_sg(urb->sg, sg, urb->num_mapped_sgs, i) {
size_t len;
size_t sg_remaining;
void *orig;
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -2561,7 +2561,7 @@ static unsigned int count_sg_trbs_needed
struct scatterlist *sg;

sg = NULL;
- num_sgs = urb->num_sgs;
+ num_sgs = urb->num_mapped_sgs;
temp = urb->transfer_buffer_length;

xhci_dbg(xhci, "count sg list trbs: \n");
@@ -2745,7 +2745,7 @@ static int queue_bulk_sg_tx(struct xhci_
return -EINVAL;

num_trbs = count_sg_trbs_needed(xhci, urb);
- num_sgs = urb->num_sgs;
+ num_sgs = urb->num_mapped_sgs;
total_packet_count = roundup(urb->transfer_buffer_length,
usb_endpoint_maxp(&urb->ep->desc));

--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -1221,6 +1221,7 @@ struct urb {
void *transfer_buffer; /* (in) associated data buffer */
dma_addr_t transfer_dma; /* (in) dma addr for transfer_buffer */
struct scatterlist *sg; /* (in) scatter gather buffer list */
+ int num_mapped_sgs; /* (internal) mapped sg entries */
int num_sgs; /* (in) number of entries in the sg list */
u32 transfer_buffer_length; /* (in) data buffer length */
u32 actual_length; /* (return) actual transfer length */



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