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xhci: Fix memory leak in ring cache deallocation.

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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@linux.intel.com>
Cc: stable@kernel.org
This commit is contained in:
Sarah Sharp 2011-05-16 13:09:08 -07:00
parent b513d44751
commit 30f89ca021
1 changed files with 3 additions and 4 deletions
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7
drivers/usb/host/xhci-mem.c
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@ -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), "