NTB: Improve index handling in B2B MW workaround

Check that b2b_mw_idx is in range of the number of memory windows when
initializing the device.  The workaround is considered to be in effect
only if the device b2b_idx is exactly UINT_MAX, instead of any index
past the last memory window.

Only print B2B MW workaround information in debugfs if the workaround is
in effect.

Signed-off-by: Allen Hubbe <Allen.Hubbe@emc.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>

diff --git a/drivers/ntb/hw/intel/ntb_hw_intel.c b/drivers/ntb/hw/intel/ntb_hw_intel.c
index c2bc56b..fc6af2d 100644 (file)
--- a/drivers/ntb/hw/intel/ntb_hw_intel.c
+++ b/drivers/ntb/hw/intel/ntb_hw_intel.c
@@ -575,10 +575,13 @@ static ssize_t ndev_debugfs_read(struct file *filp, char __user *ubuf,
                         "Connection Topology -\t%s\n",
                         ntb_topo_string(ndev->ntb.topo));
 
-       off += scnprintf(buf + off, buf_size - off,
-                        "B2B Offset -\t\t%#lx\n", ndev->b2b_off);
-       off += scnprintf(buf + off, buf_size - off,
-                        "B2B MW Idx -\t\t%d\n", ndev->b2b_idx);
+       if (ndev->b2b_idx != UINT_MAX) {
+               off += scnprintf(buf + off, buf_size - off,
+                                "B2B MW Idx -\t\t%u\n", ndev->b2b_idx);
+               off += scnprintf(buf + off, buf_size - off,
+                                "B2B Offset -\t\t%#lx\n", ndev->b2b_off);
+       }
+
        off += scnprintf(buf + off, buf_size - off,
                         "BAR4 Split -\t\t%s\n",
                         ndev->bar4_split ? "yes" : "no");
@@ -1487,7 +1490,7 @@ static int xeon_setup_b2b_mw(struct intel_ntb_dev *ndev,
        pdev = ndev_pdev(ndev);
        mmio = ndev->self_mmio;
 
-       if (ndev->b2b_idx >= ndev->mw_count) {
+       if (ndev->b2b_idx == UINT_MAX) {
                dev_dbg(ndev_dev(ndev), "not using b2b mw\n");
                b2b_bar = 0;
                ndev->b2b_off = 0;
@@ -1779,6 +1782,13 @@ static int xeon_init_ntb(struct intel_ntb_dev *ndev)
                        else
                                ndev->b2b_idx = b2b_mw_idx;
 
+                       if (ndev->b2b_idx >= ndev->mw_count) {
+                               dev_dbg(ndev_dev(ndev),
+                                       "b2b_mw_idx %d invalid for mw_count %u\n",
+                                       b2b_mw_idx, ndev->mw_count);
+                               return -EINVAL;
+                       }
+
                        dev_dbg(ndev_dev(ndev),
                                "setting up b2b mw idx %d means %d\n",
                                b2b_mw_idx, ndev->b2b_idx);
@@ -2008,7 +2018,7 @@ static inline void ndev_init_struct(struct intel_ntb_dev *ndev,
        ndev->ntb.ops = &intel_ntb_ops;
 
        ndev->b2b_off = 0;
-       ndev->b2b_idx = INT_MAX;
+       ndev->b2b_idx = UINT_MAX;
 
        ndev->bar4_split = 0;