1 files changed, 5 insertions, 2 deletions

diff --git a/drivers/infiniband/hw/qib/qib_sysfs.c b/drivers/infiniband/hw/qib/qib_sysfs.c
index dae51604cfcd..dd9cd49d0979 100644
--- a/drivers/infiniband/hw/qib/qib_sysfs.c
+++ b/drivers/infiniband/hw/qib/qib_sysfs.c
@@ -503,8 +503,11 @@ static ssize_t show_nctxts(struct device *device,
         struct qib_devdata *dd = dd_from_dev(dev);
 
         /* Return the number of user ports (contexts) available. */
-        return scnprintf(buf, PAGE_SIZE, "%u\n", dd->cfgctxts -
-                dd->first_user_ctxt);
+        /* The calculation below deals with a special case where
+         * cfgctxts is set to 1 on a single-port board. */
+        return scnprintf(buf, PAGE_SIZE, "%u\n",
+                        (dd->first_user_ctxt > dd->cfgctxts) ? 0 :
+                        (dd->cfgctxts - dd->first_user_ctxt));
 }
 
 static ssize_t show_nfreectxts(struct device *device,