From patchwork Fri Apr 3 20:27:07 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Kirsher, Jeffrey T" X-Patchwork-Id: 458049 X-Patchwork-Delegate: jeffrey.t.kirsher@intel.com Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from fraxinus.osuosl.org (fraxinus.osuosl.org [140.211.166.137]) by ozlabs.org (Postfix) with ESMTP id B2A0E14012F for ; Sat, 4 Apr 2015 07:27:30 +1100 (AEDT) Received: from localhost (localhost [127.0.0.1]) by fraxinus.osuosl.org (Postfix) with ESMTP id D9276A40BD; Fri, 3 Apr 2015 20:27:29 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from fraxinus.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 5lu9NHUOZxU8; Fri, 3 Apr 2015 20:27:27 +0000 (UTC) Received: from ash.osuosl.org (ash.osuosl.org [140.211.166.34]) by fraxinus.osuosl.org (Postfix) with ESMTP id 5AC7DA3F92; Fri, 3 Apr 2015 20:27:27 +0000 (UTC) X-Original-To: intel-wired-lan@lists.osuosl.org Delivered-To: intel-wired-lan@lists.osuosl.org Received: from whitealder.osuosl.org (whitealder.osuosl.org [140.211.166.138]) by ash.osuosl.org (Postfix) with ESMTP id 4359C1C2A8F for ; Fri, 3 Apr 2015 20:27:23 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by whitealder.osuosl.org (Postfix) with ESMTP id 40AB79215C for ; Fri, 3 Apr 2015 20:27:23 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from whitealder.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id T6c0c73BDvXF for ; Fri, 3 Apr 2015 20:27:22 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by whitealder.osuosl.org (Postfix) with ESMTP id 2844392163 for ; Fri, 3 Apr 2015 20:27:22 +0000 (UTC) Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by orsmga102.jf.intel.com with ESMTP; 03 Apr 2015 13:27:21 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.11,519,1422950400"; d="scan'208";a="476517935" Received: from lwang4-mobl1.amr.corp.intel.com (HELO jtkirshe-mobl.amr.corp.intel.com) ([10.254.109.203]) by FMSMGA003.fm.intel.com with ESMTP; 03 Apr 2015 13:27:21 -0700 From: Jeff Kirsher To: intel-wired-lan@lists.osuosl.org Date: Fri, 3 Apr 2015 13:27:07 -0700 Message-Id: <1428092835-16834-17-git-send-email-jeffrey.t.kirsher@intel.com> X-Mailer: git-send-email 1.9.3 In-Reply-To: <1428092835-16834-1-git-send-email-jeffrey.t.kirsher@intel.com> References: <1428092835-16834-1-git-send-email-jeffrey.t.kirsher@intel.com> Subject: [Intel-wired-lan] [net-next 17/25] fm10k: comment next_vf_mbx flow X-BeenThere: intel-wired-lan@lists.osuosl.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: Intel Wired Ethernet Linux Kernel Driver Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: intel-wired-lan-bounces@lists.osuosl.org Sender: "Intel-wired-lan" Add a header comment explaining why we have the somewhat crazy mailbox flow. This flow is necessary as it prevents the PF<->SM mailbox from being flooded by the VF messages, which normally trigger a message to the PF. This helps prevent the case where we see a PF mailbox timeout. Signed-off-by: Jeff Kirsher Signed-off-by: Jacob Keller Acked-by: Matthew Vick Tested-by: Krishneil Singh --- drivers/net/ethernet/intel/fm10k/fm10k_iov.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/drivers/net/ethernet/intel/fm10k/fm10k_iov.c b/drivers/net/ethernet/intel/fm10k/fm10k_iov.c index 1071f38..ce361cf 100644 --- a/drivers/net/ethernet/intel/fm10k/fm10k_iov.c +++ b/drivers/net/ethernet/intel/fm10k/fm10k_iov.c @@ -113,6 +113,13 @@ s32 fm10k_iov_mbx(struct fm10k_intfc *interface) /* lock the mailbox for transmit and receive */ fm10k_mbx_lock(interface); + /* Most VF messages sent to the PF cause the PF to respond by + * requesting from the SM mailbox. This means that too many VF + * messages processed at once could cause a mailbox timeout on the PF. + * To prevent this, store a pointer to the next VF mbx to process. Use + * that as the start of the loop so that we don't starve whichever VF + * got ignored on the previous run. + */ process_mbx: for (i = iov_data->next_vf_mbx ? : iov_data->num_vfs; i--;) { struct fm10k_vf_info *vf_info = &iov_data->vf_info[i]; @@ -141,6 +148,10 @@ process_mbx: mbx->ops.process(hw, mbx); } + /* if we stopped processing mailboxes early, update next_vf_mbx. + * Otherwise, reset next_vf_mbx, and restart loop so that we process + * the remaining mailboxes we skipped at the start. + */ if (i >= 0) { iov_data->next_vf_mbx = i + 1; } else if (iov_data->next_vf_mbx) {