IB/qib: Eliminate divide/mod in converting idx to egr buf pointer

The context init now saves a shift from rcvegrbufs_perchunk
rcvegrbufs_perchunk_shift using ilog2.   A BUG_ON() protects the
power of 2 assumption.

Signed-off-by: Mike Marciniszyn <mike.marciniszyn@qlogic.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/drivers/infiniband/hw/qib/qib_driver.c b/drivers/infiniband/hw/qib/qib_driver.c
index 23e584f4c36c..89264ffc7ee9 100644
--- a/drivers/infiniband/hw/qib/qib_driver.c
+++ b/drivers/infiniband/hw/qib/qib_driver.c
@@ -279,10 +279,10 @@ bail:
  */
 static inline void *qib_get_egrbuf(const struct qib_ctxtdata *rcd, u32 etail)
 {
-        const u32 chunk = etail / rcd->rcvegrbufs_perchunk;
-        const u32 idx =  etail % rcd->rcvegrbufs_perchunk;
+        const u32 chunk = etail >> rcd->rcvegrbufs_perchunk_shift;
+        const u32 idx =  etail & ((u32)rcd->rcvegrbufs_perchunk - 1);
 
-        return rcd->rcvegrbuf[chunk] + idx * rcd->dd->rcvegrbufsize;
+        return rcd->rcvegrbuf[chunk] + (idx << rcd->dd->rcvegrbufsize_shift);
 }
 
 /*