[PATCH 1/2] xhci: Fix memory leak in ring cache deallocation.

[Sarah Sharp]

When an endpoint ring is freed, it is either cached in a per-device ring
cache, or simply freed if the ring cache is full. If the ring was added
to the cache, then virt_dev->num_rings_cached is incremented. The cache
is designed to hold up to 31 endpoint rings, in array indexes 0 to 30.
When the device is freed (when the slot was disabled),
xhci_free_virt_device() is called, it would free the cached rings in
array indexes 0 to virt_dev->num_rings_cached.

Unfortunately, the original code in xhci_free_or_cache_endpoint_ring()
would put the first entry into the ring cache in array index 1, instead of
array index 0. This was caused by the second assignment to rings_cached:

rings_cached = virt_dev->num_rings_cached;
if (rings_cached < XHCI_MAX_RINGS_CACHED) {
virt_dev->num_rings_cached++;
rings_cached = virt_dev->num_rings_cached;
virt_dev->ring_cache[rings_cached] =
virt_dev->eps[ep_index].ring;

This meant that when the device was freed, cached rings with indexes 0 to
N would be freed, and the last cached ring in index N+1 would not be
freed. When the driver was unloaded, this caused interesting messages
like:

xhci_hcd 0000:06:00.0: dma_pool_destroy xHCI ring segments, ffff880063040000 busy

This should be queued to stable kernels back to 2.6.33.

Signed-off-by: Sarah Sharp <sarah.a.sharp-VuQAYsv1563Yd54FQh9/***@public.gmane.org>
Cc: stable-DgEjT+Ai2ygdnm+***@public.gmane.org
---
drivers/usb/host/xhci-mem.c | 7 +++----
1 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
index 6938cc8..26caba4 100644
--- a/drivers/usb/host/xhci-mem.c
+++ b/drivers/usb/host/xhci-mem.c
@@ -209,14 +209,13 @@ void xhci_free_or_cache_endpoint_ring(struct xhci_hcd *xhci,

rings_cached = virt_dev->num_rings_cached;
if (rings_cached < XHCI_MAX_RINGS_CACHED) {
- virt_dev->num_rings_cached++;
- rings_cached = virt_dev->num_rings_cached;
virt_dev->ring_cache[rings_cached] =
virt_dev->eps[ep_index].ring;
+ virt_dev->num_rings_cached++;
xhci_dbg(xhci, "Cached old ring, "
"%d ring%s cached\n",
- rings_cached,
- (rings_cached > 1) ? "s" : "");
+ virt_dev->num_rings_cached,
+ (virt_dev->num_rings_cached > 1) ? "s" : "");
} else {
xhci_ring_free(xhci, virt_dev->eps[ep_index].ring);
xhci_dbg(xhci, "Ring cache full (%d rings), "

[Sarah Sharp]

When the USB core wants to change to an alternate interface setting that
doesn't include an active endpoint, or de-configuring the device, the xHCI
driver needs to issue a Configure Endpoint command to tell the host to
drop some endpoints from the schedule. After the command completes, the
xHCI driver needs to free rings for any endpoints that were dropped.

Unfortunately, the xHCI driver wasn't actually freeing the endpoint rings
for dropped endpoints. The rings would be freed if the endpoint's
information was simply changed (and a new ring was installed), but dropped
endpoints never had their rings freed. This caused errors when the ring
segment DMA pool was freed when the xHCI driver was unloaded:

[ 5582.883995] xhci_hcd 0000:06:00.0: dma_pool_destroy xHCI ring segments, ffff88003371d000 busy
[ 5582.884002] xhci_hcd 0000:06:00.0: dma_pool_destroy xHCI ring segments, ffff880033716000 busy
[ 5582.884011] xhci_hcd 0000:06:00.0: dma_pool_destroy xHCI ring segments, ffff880033455000 busy
[ 5582.884018] xhci_hcd 0000:06:00.0: Freed segment pool
[ 5582.884026] xhci_hcd 0000:06:00.0: Freed device context pool
[ 5582.884033] xhci_hcd 0000:06:00.0: Freed small stream array pool
[ 5582.884038] xhci_hcd 0000:06:00.0: Freed medium stream array pool
[ 5582.884048] xhci_hcd 0000:06:00.0: xhci_stop completed - status = 1
[ 5582.884061] xhci_hcd 0000:06:00.0: USB bus 3 deregistered
[ 5582.884193] xhci_hcd 0000:06:00.0: PCI INT A disabled

Fix this issue and free endpoint rings when their endpoints are
successfully dropped.

This patch should be backported to kernels as old as 2.6.31.

Signed-off-by: Sarah Sharp <sarah.a.sharp-VuQAYsv1563Yd54FQh9/***@public.gmane.org>
Cc: stable-DgEjT+Ai2ygdnm+***@public.gmane.org
---
drivers/usb/host/xhci.c | 11 ++++++++++-
1 files changed, 10 insertions(+), 1 deletions(-)

diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 013e113..8f2a56e 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -1701,8 +1701,17 @@ int xhci_check_bandwidth(struct usb_hcd *hcd, struct usb_device *udev)
xhci_dbg_ctx(xhci, virt_dev->out_ctx,
LAST_CTX_TO_EP_NUM(le32_to_cpu(slot_ctx->dev_info)));

+ /* Free any rings that were dropped, but not changed. */
+ for (i = 1; i < 31; ++i) {
+ if ((ctrl_ctx->drop_flags & (1 << (i + 1))) &&
+ !(ctrl_ctx->add_flags & (1 << (i + 1))))
+ xhci_free_or_cache_endpoint_ring(xhci, virt_dev, i);
+ }
xhci_zero_in_ctx(xhci, virt_dev);
- /* Install new rings and free or cache any old rings */
+ /*
+ * Install any rings for completely new endpoints or changed endpoints,
+ * and free or cache any old rings from changed endpoints.
+ */
for (i = 1; i < 31; ++i) {
if (!virt_dev->eps[i].new_ring)
continue;

[Greg KH]

Hi Greg,
Here's two patches that fix some memory leaks in the xHCI driver's
endpoint ring deallocation. This fixes the errors I've been seeing on
dma_pool_destroy xHCI ring segments, ffff880063040000 busy
The patches are marked as needing to be backported to the stable trees.
Sarah Sharp
xhci: Fix full speed bInterval encoding. (2011-05-13 16:34:06 -0700)
git+ssh://master.kernel.org/pub/scm/linux/kernel/git/sarah/xhci.git for-usb-next

Pulled and pushed out.

thanks,

greg k-h
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