From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Kirsher Subject: [net 07/13] ice: Use order_base_2 to calculate higher power of 2 Date: Thu, 23 Aug 2018 12:14:57 -0700 Message-ID: <20180823191503.15804-8-jeffrey.t.kirsher@intel.com> References: <20180823191503.15804-1-jeffrey.t.kirsher@intel.com> Cc: Jacob Keller , netdev@vger.kernel.org, nhorman@redhat.com, sassmann@redhat.com, jogreene@redhat.com, Anirudh Venkataramanan , Jeff Kirsher To: davem@davemloft.net Return-path: Received: from mga11.intel.com ([192.55.52.93]:16930 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726081AbeHWWnb (ORCPT ); Thu, 23 Aug 2018 18:43:31 -0400 In-Reply-To: <20180823191503.15804-1-jeffrey.t.kirsher@intel.com> Sender: netdev-owner@vger.kernel.org List-ID: From: Jacob Keller Currently, we use a combination of ilog2 and is_power_of_2() to calculate the next power of 2 for the qcount. This appears to be causing a warning on some combinations of GCC and the Linux kernel: MODPOST 1 modules WARNING: "____ilog2_NaN" [ice.ko] undefined! This appears to because because GCC realizes that qcount could be zero in some circumstances and thus attempts to link against the intentionally undefined ___ilog2_NaN function. The order_base_2 function is intentionally defined to return 0 when passed 0 as an argument, and thus will be safe to use here. This not only fixes the warning but makes the resulting code slightly cleaner, and is really what we should have used originally. Also update the comment to make it more clear that we are rounding up, not just incrementing the ilog2 of qcount unconditionally. Signed-off-by: Jacob Keller Signed-off-by: Anirudh Venkataramanan Tested-by: Tony Brelinski Signed-off-by: Jeff Kirsher --- drivers/net/ethernet/intel/ice/ice_main.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) diff --git a/drivers/net/ethernet/intel/ice/ice_main.c b/drivers/net/ethernet/intel/ice/ice_main.c index f3ba4f76b6cb..3eff1d2d1543 100644 --- a/drivers/net/ethernet/intel/ice/ice_main.c +++ b/drivers/net/ethernet/intel/ice/ice_main.c @@ -1313,11 +1313,8 @@ static void ice_vsi_setup_q_map(struct ice_vsi *vsi, struct ice_vsi_ctx *ctxt) qcount = numq_tc; } - /* find higher power-of-2 of qcount */ - pow = ilog2(qcount); - - if (!is_power_of_2(qcount)) - pow++; + /* find the (rounded up) power-of-2 of qcount */ + pow = order_base_2(qcount); for (i = 0; i < ICE_MAX_TRAFFIC_CLASS; i++) { if (!(vsi->tc_cfg.ena_tc & BIT(i))) { -- 2.17.1