From mboxrd@z Thu Jan 1 00:00:00 1970 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 22D40C433F5 for ; Thu, 17 Feb 2022 13:13:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240724AbiBQNNX (ORCPT ); Thu, 17 Feb 2022 08:13:23 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:56968 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229536AbiBQNNS (ORCPT ); Thu, 17 Feb 2022 08:13:18 -0500 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 0EF4911A2E for ; Thu, 17 Feb 2022 05:13:03 -0800 (PST) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id CA3D11474; Thu, 17 Feb 2022 05:12:55 -0800 (PST) Received: from e120937-lin.home (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id F335D3F66F; Thu, 17 Feb 2022 05:12:53 -0800 (PST) From: Cristian Marussi To: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: sudeep.holla@arm.com, james.quinlan@broadcom.com, Jonathan.Cameron@Huawei.com, f.fainelli@gmail.com, etienne.carriere@linaro.org, vincent.guittot@linaro.org, souvik.chakravarty@arm.com, peter.hilber@opensynergy.com, igor.skalkin@opensynergy.com, cristian.marussi@arm.com, "Michael S. Tsirkin" , virtualization@lists.linux-foundation.org Subject: [PATCH v5 2/8] firmware: arm_scmi: Review virtio free_list handling Date: Thu, 17 Feb 2022 13:12:28 +0000 Message-Id: <20220217131234.50328-3-cristian.marussi@arm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20220217131234.50328-1-cristian.marussi@arm.com> References: <20220217131234.50328-1-cristian.marussi@arm.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add a new spinlock dedicated to the access of the TX free list and a couple of helpers to get and put messages back and forth from the free_list. Cc: "Michael S. Tsirkin" Cc: Igor Skalkin Cc: Peter Hilber Cc: virtualization@lists.linux-foundation.org Signed-off-by: Cristian Marussi --- drivers/firmware/arm_scmi/virtio.c | 88 +++++++++++++++++++----------- 1 file changed, 57 insertions(+), 31 deletions(-) diff --git a/drivers/firmware/arm_scmi/virtio.c b/drivers/firmware/arm_scmi/virtio.c index ed00b072e981..7ec4085cee7e 100644 --- a/drivers/firmware/arm_scmi/virtio.c +++ b/drivers/firmware/arm_scmi/virtio.c @@ -40,20 +40,23 @@ * * @vqueue: Associated virtqueue * @cinfo: SCMI Tx or Rx channel + * @free_lock: Protects access to the @free_list. * @free_list: List of unused scmi_vio_msg, maintained for Tx channels only * @is_rx: Whether channel is an Rx channel * @max_msg: Maximum number of pending messages for this channel. - * @lock: Protects access to all members except users. + * @lock: Protects access to all members except users, free_list. * @shutdown_done: A reference to a completion used when freeing this channel. * @users: A reference count to currently active users of this channel. */ struct scmi_vio_channel { struct virtqueue *vqueue; struct scmi_chan_info *cinfo; + /* lock to protect access to the free list. */ + spinlock_t free_lock; struct list_head free_list; bool is_rx; unsigned int max_msg; - /* lock to protect access to all members except users. */ + /* lock to protect access to all members except users, free_list */ spinlock_t lock; struct completion *shutdown_done; refcount_t users; @@ -134,18 +137,49 @@ static void scmi_vio_channel_cleanup_sync(struct scmi_vio_channel *vioch) wait_for_completion(vioch->shutdown_done); } +/* Assumes to be called with vio channel acquired already */ +static struct scmi_vio_msg * +scmi_virtio_get_free_msg(struct scmi_vio_channel *vioch) +{ + unsigned long flags; + struct scmi_vio_msg *msg; + + spin_lock_irqsave(&vioch->free_lock, flags); + if (list_empty(&vioch->free_list)) { + spin_unlock_irqrestore(&vioch->free_lock, flags); + return NULL; + } + + msg = list_first_entry(&vioch->free_list, typeof(*msg), list); + list_del_init(&msg->list); + spin_unlock_irqrestore(&vioch->free_lock, flags); + + return msg; +} + +/* Assumes to be called with vio channel acquired already */ +static void scmi_virtio_put_free_msg(struct scmi_vio_channel *vioch, + struct scmi_vio_msg *msg) +{ + unsigned long flags; + + spin_lock_irqsave(&vioch->free_lock, flags); + list_add_tail(&msg->list, &vioch->free_list); + spin_unlock_irqrestore(&vioch->free_lock, flags); +} + static bool scmi_vio_have_vq_rx(struct virtio_device *vdev) { return virtio_has_feature(vdev, VIRTIO_SCMI_F_P2A_CHANNELS); } static int scmi_vio_feed_vq_rx(struct scmi_vio_channel *vioch, - struct scmi_vio_msg *msg, - struct device *dev) + struct scmi_vio_msg *msg) { struct scatterlist sg_in; int rc; unsigned long flags; + struct device *dev = &vioch->vqueue->vdev->dev; sg_init_one(&sg_in, msg->input, VIRTIO_SCMI_MAX_PDU_SIZE); @@ -162,17 +196,17 @@ static int scmi_vio_feed_vq_rx(struct scmi_vio_channel *vioch, return rc; } +/* + * Assume to be called with channel already acquired or not ready at all; + * vioch->lock MUST NOT have been already acquired. + */ static void scmi_finalize_message(struct scmi_vio_channel *vioch, struct scmi_vio_msg *msg) { - if (vioch->is_rx) { - scmi_vio_feed_vq_rx(vioch, msg, vioch->cinfo->dev); - } else { - /* Here IRQs are assumed to be already disabled by the caller */ - spin_lock(&vioch->lock); - list_add(&msg->list, &vioch->free_list); - spin_unlock(&vioch->lock); - } + if (vioch->is_rx) + scmi_vio_feed_vq_rx(vioch, msg); + else + scmi_virtio_put_free_msg(vioch, msg); } static void scmi_vio_complete_cb(struct virtqueue *vqueue) @@ -284,7 +318,6 @@ static bool virtio_chan_available(struct device *dev, int idx) static int virtio_chan_setup(struct scmi_chan_info *cinfo, struct device *dev, bool tx) { - unsigned long flags; struct scmi_vio_channel *vioch; int index = tx ? VIRTIO_SCMI_VQ_TX : VIRTIO_SCMI_VQ_RX; int i; @@ -314,13 +347,7 @@ static int virtio_chan_setup(struct scmi_chan_info *cinfo, struct device *dev, if (!msg->input) return -ENOMEM; - if (tx) { - spin_lock_irqsave(&vioch->lock, flags); - list_add_tail(&msg->list, &vioch->free_list); - spin_unlock_irqrestore(&vioch->lock, flags); - } else { - scmi_vio_feed_vq_rx(vioch, msg, cinfo->dev); - } + scmi_finalize_message(vioch, msg); } scmi_vio_channel_ready(vioch, cinfo); @@ -354,33 +381,31 @@ static int virtio_send_message(struct scmi_chan_info *cinfo, if (!scmi_vio_channel_acquire(vioch)) return -EINVAL; - spin_lock_irqsave(&vioch->lock, flags); - - if (list_empty(&vioch->free_list)) { - spin_unlock_irqrestore(&vioch->lock, flags); + msg = scmi_virtio_get_free_msg(vioch); + if (!msg) { scmi_vio_channel_release(vioch); return -EBUSY; } - msg = list_first_entry(&vioch->free_list, typeof(*msg), list); - list_del(&msg->list); - msg_tx_prepare(msg->request, xfer); sg_init_one(&sg_out, msg->request, msg_command_size(xfer)); sg_init_one(&sg_in, msg->input, msg_response_size(xfer)); + spin_lock_irqsave(&vioch->lock, flags); + rc = virtqueue_add_sgs(vioch->vqueue, sgs, 1, 1, msg, GFP_ATOMIC); - if (rc) { - list_add(&msg->list, &vioch->free_list); + if (rc) dev_err(vioch->cinfo->dev, "failed to add to TX virtqueue (%d)\n", rc); - } else { + else virtqueue_kick(vioch->vqueue); - } spin_unlock_irqrestore(&vioch->lock, flags); + if (rc) + scmi_virtio_put_free_msg(vioch, msg); + scmi_vio_channel_release(vioch); return rc; @@ -457,6 +482,7 @@ static int scmi_vio_probe(struct virtio_device *vdev) unsigned int sz; spin_lock_init(&channels[i].lock); + spin_lock_init(&channels[i].free_lock); INIT_LIST_HEAD(&channels[i].free_list); channels[i].vqueue = vqs[i]; -- 2.17.1