netdev - RE: [PATCH] net: mana: add msix index sharing between EQs

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Date: Tue, 12 Dec 2023 02:51:50 +0000
From: Long Li <longli@...rosoft.com>
To: Konstantin Taranov <kotaranov@...ux.microsoft.com>, Konstantin Taranov
	<kotaranov@...rosoft.com>, KY Srinivasan <kys@...rosoft.com>, Haiyang Zhang
	<haiyangz@...rosoft.com>, "wei.liu@...nel.org" <wei.liu@...nel.org>,
	"kuba@...nel.org" <kuba@...nel.org>, "leon@...nel.org" <leon@...nel.org>,
	Dexuan Cui <decui@...rosoft.com>, "edumazet@...gle.com"
	<edumazet@...gle.com>, "cai.huoqing@...ux.dev" <cai.huoqing@...ux.dev>,
	"pabeni@...hat.com" <pabeni@...hat.com>, "davem@...emloft.net"
	<davem@...emloft.net>
CC: "linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-rdma@...r.kernel.org" <linux-rdma@...r.kernel.org>
Subject: RE: [PATCH] net: mana: add msix index sharing between EQs

> @@ -502,12 +512,19 @@ static void mana_gd_deregiser_irq(struct gdma_queue
> *queue)
>  	if (WARN_ON(msix_index >= gc->num_msix_usable))
>  		return;
> 
> -	gic = &gc->irq_contexts[msix_index];
> -	gic->handler = NULL;
> -	gic->arg = NULL;
> -
>  	spin_lock_irqsave(&r->lock, flags);
> -	bitmap_clear(r->map, msix_index, 1);
> +	gic = &gc->irq_contexts[msix_index];
> +	list_for_each_entry_rcu(eq, &gic->eq_list, entry) {
> +		if (queue == eq) {
> +			list_del_rcu(&eq->entry);
> +			synchronize_rcu();

The usage of RCU is questionable in an atomic context. This code needs to be tested with multiple EQs.

Long

> +			break;
> +		}
> +	}
> +	if (list_empty(&gic->eq_list)) {
> +		gic->handler = NULL;
> +		bitmap_clear(r->map, msix_index, 1);
> +	}
>  	spin_unlock_irqrestore(&r->lock, flags);
> 
>  	queue->eq.msix_index = INVALID_PCI_MSIX_INDEX; @@ -587,7 +604,8
> @@ static int mana_gd_create_eq(struct gdma_dev *gd,
>  	u32 log2_num_entries;
>  	int err;
> 
> -	queue->eq.msix_index = INVALID_PCI_MSIX_INDEX;
> +	queue->eq.msix_index = spec->eq.msix_index;
> +	queue->id = INVALID_QUEUE_ID;
> 
>  	log2_num_entries = ilog2(queue->queue_size / GDMA_EQE_SIZE);
> 
> @@ -819,6 +837,7 @@ free_q:
>  	kfree(queue);
>  	return err;
>  }
> +EXPORT_SYMBOL_NS(mana_gd_create_mana_eq, NET_MANA);
> 
>  int mana_gd_create_mana_wq_cq(struct gdma_dev *gd,
>  			      const struct gdma_queue_spec *spec, @@ -895,6
> +914,7 @@ void mana_gd_destroy_queue(struct gdma_context *gc, struct
> gdma_queue *queue)
>  	mana_gd_free_memory(gmi);
>  	kfree(queue);
>  }
> +EXPORT_SYMBOL_NS(mana_gd_destroy_queue, NET_MANA);
> 
>  int mana_gd_verify_vf_version(struct pci_dev *pdev)  { @@ -1217,9 +1237,14
> @@ int mana_gd_poll_cq(struct gdma_queue *cq, struct gdma_comp *comp, int
> num_cqe)  static irqreturn_t mana_gd_intr(int irq, void *arg)  {
>  	struct gdma_irq_context *gic = arg;
> +	struct list_head *eq_list = &gic->eq_list;
> +	struct gdma_queue *eq;
> 
> -	if (gic->handler)
> -		gic->handler(gic->arg);
> +	if (gic->handler) {
> +		list_for_each_entry_rcu(eq, eq_list, entry) {
> +			gic->handler(eq);
> +		}
> +	}
> 
>  	return IRQ_HANDLED;
>  }
> @@ -1272,7 +1297,7 @@ static int mana_gd_setup_irqs(struct pci_dev *pdev)
>  	for (i = 0; i < nvec; i++) {
>  		gic = &gc->irq_contexts[i];
>  		gic->handler = NULL;
> -		gic->arg = NULL;
> +		INIT_LIST_HEAD(&gic->eq_list);
> 
>  		if (!i)
>  			snprintf(gic->name, MANA_IRQ_NAME_SZ,
> "mana_hwc@pci:%s", diff --git
> a/drivers/net/ethernet/microsoft/mana/hw_channel.c
> b/drivers/net/ethernet/microsoft/mana/hw_channel.c
> index 9d1cd3b..0a5fc39 100644
> --- a/drivers/net/ethernet/microsoft/mana/hw_channel.c
> +++ b/drivers/net/ethernet/microsoft/mana/hw_channel.c
> @@ -300,6 +300,7 @@ static int mana_hwc_create_gdma_eq(struct
> hw_channel_context *hwc,
>  	spec.eq.context = ctx;
>  	spec.eq.callback = cb;
>  	spec.eq.log2_throttle_limit =
> DEFAULT_LOG2_THROTTLING_FOR_ERROR_EQ;
> +	spec.eq.msix_index = INVALID_PCI_MSIX_INDEX;
> 
>  	return mana_gd_create_hwc_queue(hwc->gdma_dev, &spec, queue);  }
> diff --git a/drivers/net/ethernet/microsoft/mana/mana_en.c
> b/drivers/net/ethernet/microsoft/mana/mana_en.c
> index fc3d290..8718c04 100644
> --- a/drivers/net/ethernet/microsoft/mana/mana_en.c
> +++ b/drivers/net/ethernet/microsoft/mana/mana_en.c
> @@ -1242,6 +1242,7 @@ static int mana_create_eq(struct mana_context *ac)
>  	spec.eq.callback = NULL;
>  	spec.eq.context = ac->eqs;
>  	spec.eq.log2_throttle_limit = LOG2_EQ_THROTTLE;
> +	spec.eq.msix_index = INVALID_PCI_MSIX_INDEX;
> 
>  	for (i = 0; i < gc->max_num_queues; i++) {
>  		err = mana_gd_create_mana_eq(gd, &spec, &ac->eqs[i].eq); diff
> --git a/include/net/mana/gdma.h b/include/net/mana/gdma.h index
> 88b6ef7..8d6569d 100644
> --- a/include/net/mana/gdma.h
> +++ b/include/net/mana/gdma.h
> @@ -293,6 +293,7 @@ struct gdma_queue {
> 
>  	u32 head;
>  	u32 tail;
> +	struct list_head entry;
> 
>  	/* Extra fields specific to EQ/CQ. */
>  	union {
> @@ -328,6 +329,7 @@ struct gdma_queue_spec {
>  			void *context;
> 
>  			unsigned long log2_throttle_limit;
> +			unsigned int msix_index;
>  		} eq;
> 
>  		struct {
> @@ -344,7 +346,7 @@ struct gdma_queue_spec {
> 
>  struct gdma_irq_context {
>  	void (*handler)(void *arg);
> -	void *arg;
> +	struct list_head eq_list;
>  	char name[MANA_IRQ_NAME_SZ];
>  };
> 
> --
> 2.43.0