[PATCH 16/29] ioat: ignore reserved bits for chancnt and xfercap

Dan Williams
2009-09-04T02:32:04Z

Don't trust that the reserved bits are always zero, also sanity check
the returned value.

Signed-off-by: Maciej Sosnowski <maciej.sosnowski@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
drivers/dma/ioat/dma.c | 7 +++++++
drivers/dma/ioat/dma_v2.c | 7 +++++++
2 files changed, 14 insertions(+), 0 deletions(-)

diff --git a/drivers/dma/ioat/dma.c b/drivers/dma/ioat/dma.c
index 08417ad..5173ba9 100644
--- a/drivers/dma/ioat/dma.c
+++ b/drivers/dma/ioat/dma.c
@@ -132,7 +132,14 @@ static int ioat1_enumerate_channels(struct ioatdma_device *device)

INIT_LIST_HEAD(&dma->channels);
dma->chancnt = readb(device->reg_base + IOAT_CHANCNT_OFFSET);
+ dma->chancnt &= 0x1f; /* bits [4:0] valid */
+ if (dma->chancnt > ARRAY_SIZE(device->idx)) {
+ dev_warn(dev, "(%d) exceeds max supported channels (%zu)\n",
+ dma->chancnt, ARRAY_SIZE(device->idx));
+ dma->chancnt = ARRAY_SIZE(device->idx);
+ }
xfercap_scale = readb(device->reg_base + IOAT_XFERCAP_OFFSET);
+ xfercap_scale &= 0x1f; /* bits [4:0] valid */
xfercap = (xfercap_scale == 0 ? -1 : (1UL << xfercap_scale));
dev_dbg(dev, "%s: xfercap = %d\n", __func__, xfercap);

diff --git a/drivers/dma/ioat/dma_v2.c b/drivers/dma/ioat/dma_v2.c
index 9bd3d14..589bbc3 100644
--- a/drivers/dma/ioat/dma_v2.c
+++ b/drivers/dma/ioat/dma_v2.c
@@ -360,7 +360,14 @@ static int ioat2_enumerate_channels(struct ioatdma_device *device)

INIT_LIST_HEAD(&dma->channels);
dma->chancnt = readb(device->reg_base + IOAT_CHANCNT_OFFSET);
+ dma->chancnt &= 0x1f; /* bits [4:0] valid */
+ if (dma->chancnt > ARRAY_SIZE(device->idx)) {
+ dev_warn(dev, "(%d) exceeds max supported channels (%zu)\n",
+ dma->chancnt, ARRAY_SIZE(device->idx));
+ dma->chancnt = ARRAY_SIZE(device->idx);
+ }
xfercap_log = readb(device->reg_base + IOAT_XFERCAP_OFFSET);
+ xfercap_log &= 0x1f; /* bits [4:0] valid */
if (xfercap_log == 0)
return 0;
dev_dbg(dev, "%s: xfercap = %d\n", __func__, 1 << xfercap_log);