From patchwork Mon Jul 25 09:37:28 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Saurabh Singh Sengar X-Patchwork-Id: 593712 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D2A9BC43334 for ; Mon, 25 Jul 2022 09:37:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233967AbiGYJhf (ORCPT ); Mon, 25 Jul 2022 05:37:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42748 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232340AbiGYJhe (ORCPT ); Mon, 25 Jul 2022 05:37:34 -0400 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 4627B9FF3; Mon, 25 Jul 2022 02:37:33 -0700 (PDT) Received: from linuxonhyperv3.guj3yctzbm1etfxqx2vob5hsef.xx.internal.cloudapp.net (linux.microsoft.com [13.77.154.182]) by linux.microsoft.com (Postfix) with ESMTPSA id E635D20FE02B; Mon, 25 Jul 2022 02:37:32 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com E635D20FE02B DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1658741852; bh=6KuO3lg0k3uiAOGDOvjAhWv7j6XUbuiAPwNtN8EgbzM=; h=From:To:Subject:Date:From; b=VQdheEs3/ZVsFIPjwql2MvNIvHJLSaXycChX/7GsYWqDPvaCI+rMaBWKHtaNo6EEp h16n5/9FUq2jKAwQhXoDZnD4SymZnAWBfXHh9Z79X63pQQDLwzeVBKovwNeN8xvEat 7XT+/fu18FVptQVDsLqbTsld+kvkXjl75VLGAZTI= From: Saurabh Sengar To: kys@microsoft.com, haiyangz@microsoft.com, sthemmin@microsoft.com, wei.liu@kernel.org, decui@microsoft.com, jejb@linux.ibm.com, martin.petersen@oracle.com, linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org Subject: [PATCH] Drivers: hv: vmbus: Optimize vmbus_on_event Date: Mon, 25 Jul 2022 02:37:28 -0700 Message-Id: <1658741848-4210-1-git-send-email-ssengar@linux.microsoft.com> X-Mailer: git-send-email 1.8.3.1 Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org In the vmbus_on_event loop, 2 jiffies timer will not serve the purpose if callback_fn takes longer. For effective use move this check inside of callback functions where needed. Out of all the VMbus drivers using vmbus_on_event, only storvsc has a high packet volume, thus add this limit only in storvsc callback for now. There is no apparent benefit of loop itself because this tasklet will be scheduled anyway again if there are packets left in ring buffer. This patch removes this unnecessary loop as well. Signed-off-by: Saurabh Sengar Reviewed-by: Michael Kelley --- drivers/hv/connection.c | 33 ++++++++++++++------------------- drivers/scsi/storvsc_drv.c | 9 +++++++++ 2 files changed, 23 insertions(+), 19 deletions(-) diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c index eca7afd..9dc27e5 100644 --- a/drivers/hv/connection.c +++ b/drivers/hv/connection.c @@ -431,34 +431,29 @@ struct vmbus_channel *relid2channel(u32 relid) void vmbus_on_event(unsigned long data) { struct vmbus_channel *channel = (void *) data; - unsigned long time_limit = jiffies + 2; + void (*callback_fn)(void *context); trace_vmbus_on_event(channel); hv_debug_delay_test(channel, INTERRUPT_DELAY); - do { - void (*callback_fn)(void *); - /* A channel once created is persistent even when - * there is no driver handling the device. An - * unloading driver sets the onchannel_callback to NULL. - */ - callback_fn = READ_ONCE(channel->onchannel_callback); - if (unlikely(callback_fn == NULL)) - return; - - (*callback_fn)(channel->channel_callback_context); + /* A channel once created is persistent even when + * there is no driver handling the device. An + * unloading driver sets the onchannel_callback to NULL. + */ + callback_fn = READ_ONCE(channel->onchannel_callback); + if (unlikely(!callback_fn)) + return; - if (channel->callback_mode != HV_CALL_BATCHED) - return; + (*callback_fn)(channel->channel_callback_context); - if (likely(hv_end_read(&channel->inbound) == 0)) - return; + if (channel->callback_mode != HV_CALL_BATCHED) + return; - hv_begin_read(&channel->inbound); - } while (likely(time_before(jiffies, time_limit))); + if (likely(hv_end_read(&channel->inbound) == 0)) + return; - /* The time limit (2 jiffies) has been reached */ + hv_begin_read(&channel->inbound); tasklet_schedule(&channel->callback_event); } diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c index fe000da..c457e6b 100644 --- a/drivers/scsi/storvsc_drv.c +++ b/drivers/scsi/storvsc_drv.c @@ -60,6 +60,9 @@ #define VMSTOR_PROTO_VERSION_WIN8_1 VMSTOR_PROTO_VERSION(6, 0) #define VMSTOR_PROTO_VERSION_WIN10 VMSTOR_PROTO_VERSION(6, 2) +/* channel callback timeout in ms */ +#define CALLBACK_TIMEOUT 2 + /* Packet structure describing virtual storage requests. */ enum vstor_packet_operation { VSTOR_OPERATION_COMPLETE_IO = 1, @@ -1204,6 +1207,7 @@ static void storvsc_on_channel_callback(void *context) struct hv_device *device; struct storvsc_device *stor_device; struct Scsi_Host *shost; + unsigned long time_limit = jiffies + msecs_to_jiffies(CALLBACK_TIMEOUT); if (channel->primary_channel != NULL) device = channel->primary_channel->device_obj; @@ -1224,6 +1228,11 @@ static void storvsc_on_channel_callback(void *context) u32 minlen = rqst_id ? sizeof(struct vstor_packet) : sizeof(enum vstor_packet_operation); + if (unlikely(time_after(jiffies, time_limit))) { + hv_pkt_iter_close(channel); + return; + } + if (pktlen < minlen) { dev_err(&device->device, "Invalid pkt: id=%llu, len=%u, minlen=%u\n",