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powerpc/iommu: Prevent false TCE leak message

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When a device DMA window includes the address 0, it's reserved in the
TCE bitmap to avoid returning that address to drivers.

When the device is removed, the bitmap is checked for any mappings not
removed by the driver, indicating a possible DMA mapping leak. Since the
reserved address is not cleared, a message is printed, warning of such a
leak.

Check for the reservation, and clear it before checking for any other
standing mappings.

Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Thadeu Lima de Souza Cascardo 2012-12-28 09:08:51 +00:00 committed by Benjamin Herrenschmidt
parent d69f1d7fa1
commit 7f966d394d
1 changed files with 7 additions and 0 deletions
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7
arch/powerpc/kernel/iommu.c
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@ -717,6 +717,13 @@ void iommu_free_table(struct iommu_table *tbl, const char *node_name)
return;
}
/*
* In case we have reserved the first bit, we should not emit
* the warning below.
*/
if (tbl->it_offset == 0)
clear_bit(0, tbl->it_map);
/* verify that table contains no entries */
if (!bitmap_empty(tbl->it_map, tbl->it_size))
pr_warn("%s: Unexpected TCEs for %s\n", __func__, node_name);