sfc: fix ef100 design-param checking

The handling of the RXQ/TXQ size granularity design-params had two
 problems: it had a 64-bit divide that didn't build on 32-bit platforms,
 and it could divide by zero if the NIC supplied 0 as the value of the
 design-param.  Fix both by checking for 0 and for a granularity bigger
 than our min-size; if the granularity <= EFX_MIN_DMAQ_SIZE then it fits
 in 32 bits, so we can cast it to u32 for the divide.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Edward Cree <ecree@solarflare.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/sfc/ef100_nic.c b/drivers/net/ethernet/sfc/ef100_nic.c
index 36598d0..206d70f 100644 (file)
--- a/drivers/net/ethernet/sfc/ef100_nic.c
+++ b/drivers/net/ethernet/sfc/ef100_nic.c
@@ -979,7 +979,8 @@ static int ef100_process_design_param(struct efx_nic *efx,
                 * EFX_MIN_DMAQ_SIZE is divisible by GRANULARITY.
                 * This is very unlikely to fail.
                 */
-               if (EFX_MIN_DMAQ_SIZE % reader->value) {
+               if (!reader->value || reader->value > EFX_MIN_DMAQ_SIZE ||
+                   EFX_MIN_DMAQ_SIZE % (u32)reader->value) {
                        netif_err(efx, probe, efx->net_dev,
                                  "%s size granularity is %llu, can't guarantee safety\n",
                                  reader->type == ESE_EF100_DP_GZ_RXQ_SIZE_GRANULARITY ? "RXQ" : "TXQ",