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Message-ID: <b5b4b96f-e512-4c1a-b749-f9fc3e7c2fcf@linux.ibm.com>
Date: Fri, 16 Feb 2024 15:13:23 +0100
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From: Wenjia Zhang <wenjia@linux.ibm.com>
Subject: Re: [PATCH net-next 06/15] net/smc: implement DMB-related operations
 of loopback-ism
To: Wen Gu <guwen@linux.alibaba.com>, wintera@linux.ibm.com, hca@linux.ibm.com,
        gor@linux.ibm.com, agordeev@linux.ibm.com, davem@davemloft.net,
        edumazet@google.com, kuba@kernel.org, pabeni@redhat.com,
        jaka@linux.ibm.com, Gerd Bayer <gbayer@linux.ibm.com>
Cc: borntraeger@linux.ibm.com, svens@linux.ibm.com, alibuda@linux.alibaba.com,
        tonylu@linux.alibaba.com, linux-s390@vger.kernel.org,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20240111120036.109903-1-guwen@linux.alibaba.com>
 <20240111120036.109903-7-guwen@linux.alibaba.com>
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In-Reply-To: <20240111120036.109903-7-guwen@linux.alibaba.com>
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On 11.01.24 13:00, Wen Gu wrote:
> This implements DMB (un)registration and data move operations of
> loopback-ism device.
> 
> Signed-off-by: Wen Gu <guwen@linux.alibaba.com>
> ---
>   net/smc/smc_cdc.c      |   6 ++
>   net/smc/smc_cdc.h      |   1 +
>   net/smc/smc_loopback.c | 133 ++++++++++++++++++++++++++++++++++++++++-
>   net/smc/smc_loopback.h |  13 ++++
>   4 files changed, 150 insertions(+), 3 deletions(-)
> 
> diff --git a/net/smc/smc_cdc.c b/net/smc/smc_cdc.c
> index 3c06625ceb20..c820ef197610 100644
> --- a/net/smc/smc_cdc.c
> +++ b/net/smc/smc_cdc.c
> @@ -410,6 +410,12 @@ static void smc_cdc_msg_recv(struct smc_sock *smc, struct smc_cdc_msg *cdc)
>   static void smcd_cdc_rx_tsklet(struct tasklet_struct *t)
>   {
>   	struct smc_connection *conn = from_tasklet(conn, t, rx_tsklet);
> +
> +	smcd_cdc_rx_handler(conn);
> +}
> +
> +void smcd_cdc_rx_handler(struct smc_connection *conn)
> +{
>   	struct smcd_cdc_msg *data_cdc;
>   	struct smcd_cdc_msg cdc;
>   	struct smc_sock *smc;
> diff --git a/net/smc/smc_cdc.h b/net/smc/smc_cdc.h
> index 696cc11f2303..11559d4ebf2b 100644
> --- a/net/smc/smc_cdc.h
> +++ b/net/smc/smc_cdc.h
> @@ -301,5 +301,6 @@ int smcr_cdc_msg_send_validation(struct smc_connection *conn,
>   				 struct smc_wr_buf *wr_buf);
>   int smc_cdc_init(void) __init;
>   void smcd_cdc_rx_init(struct smc_connection *conn);
> +void smcd_cdc_rx_handler(struct smc_connection *conn);
>   
>   #endif /* SMC_CDC_H */
> diff --git a/net/smc/smc_loopback.c b/net/smc/smc_loopback.c
> index 353d4a2d69a1..f72e7b24fc1a 100644
> --- a/net/smc/smc_loopback.c
> +++ b/net/smc/smc_loopback.c
> @@ -15,11 +15,13 @@
>   #include <linux/types.h>
>   #include <net/smc.h>
>   
> +#include "smc_cdc.h"
>   #include "smc_ism.h"
>   #include "smc_loopback.h"
>   
>   #if IS_ENABLED(CONFIG_SMC_LO)
>   #define SMC_LO_V2_CAPABLE	0x1 /* loopback-ism acts as ISMv2 */
> +#define SMC_DMA_ADDR_INVALID	(~(dma_addr_t)0)
>   
>   static const char smc_lo_dev_name[] = "loopback-ism";
>   static struct smc_lo_dev *lo_dev;
> @@ -50,6 +52,97 @@ static int smc_lo_query_rgid(struct smcd_dev *smcd, struct smcd_gid *rgid,
>   	return 0;
>   }
>   
> +static int smc_lo_register_dmb(struct smcd_dev *smcd, struct smcd_dmb *dmb,
> +			       void *client_priv)
> +{
> +	struct smc_lo_dmb_node *dmb_node, *tmp_node;
> +	struct smc_lo_dev *ldev = smcd->priv;
> +	int sba_idx, order, rc;
> +	struct page *pages;
> +
> +	/* check space for new dmb */
> +	for_each_clear_bit(sba_idx, ldev->sba_idx_mask, SMC_LO_MAX_DMBS) {
> +		if (!test_and_set_bit(sba_idx, ldev->sba_idx_mask))
> +			break;
> +	}
> +	if (sba_idx == SMC_LO_MAX_DMBS)
> +		return -ENOSPC;
> +
> +	dmb_node = kzalloc(sizeof(*dmb_node), GFP_KERNEL);
> +	if (!dmb_node) {
> +		rc = -ENOMEM;
> +		goto err_bit;
> +	}
> +
> +	dmb_node->sba_idx = sba_idx;
> +	order = get_order(dmb->dmb_len);
> +	pages = alloc_pages(GFP_KERNEL | __GFP_NOWARN |
> +			    __GFP_NOMEMALLOC | __GFP_COMP |
> +			    __GFP_NORETRY | __GFP_ZERO,
> +			    order);
> +	if (!pages) {
> +		rc = -ENOMEM;
> +		goto err_node;
> +	}
> +	dmb_node->cpu_addr = (void *)page_address(pages);
> +	dmb_node->len = dmb->dmb_len;
> +	dmb_node->dma_addr = SMC_DMA_ADDR_INVALID;
> +
> +again:
> +	/* add new dmb into hash table */
> +	get_random_bytes(&dmb_node->token, sizeof(dmb_node->token));
> +	write_lock(&ldev->dmb_ht_lock);
> +	hash_for_each_possible(ldev->dmb_ht, tmp_node, list, dmb_node->token) {
> +		if (tmp_node->token == dmb_node->token) {
> +			write_unlock(&ldev->dmb_ht_lock);
> +			goto again;
> +		}
> +	}
> +	hash_add(ldev->dmb_ht, &dmb_node->list, dmb_node->token);
> +	write_unlock(&ldev->dmb_ht_lock);
> +
The write_lock_irqsave()/write_unlock_irqrestore() and 
read_lock_irqsave()/read_unlock_irqrestore()should be used instead of 
write_lock()/write_unlock() and read_lock()/read_unlock() in order to 
keep the lock irq-safe.

> +	dmb->sba_idx = dmb_node->sba_idx;
> +	dmb->dmb_tok = dmb_node->token;
> +	dmb->cpu_addr = dmb_node->cpu_addr;
> +	dmb->dma_addr = dmb_node->dma_addr;
> +	dmb->dmb_len = dmb_node->len;
> +
> +	return 0;
> +
> +err_node:
> +	kfree(dmb_node);
> +err_bit:
> +	clear_bit(sba_idx, ldev->sba_idx_mask);
> +	return rc;
> +}
> +
> +static int smc_lo_unregister_dmb(struct smcd_dev *smcd, struct smcd_dmb *dmb)
> +{
> +	struct smc_lo_dmb_node *dmb_node = NULL, *tmp_node;
> +	struct smc_lo_dev *ldev = smcd->priv;
> +
> +	/* remove dmb from hash table */
> +	write_lock(&ldev->dmb_ht_lock);
> +	hash_for_each_possible(ldev->dmb_ht, tmp_node, list, dmb->dmb_tok) {
> +		if (tmp_node->token == dmb->dmb_tok) {
> +			dmb_node = tmp_node;
> +			break;
> +		}
> +	}
> +	if (!dmb_node) {
> +		write_unlock(&ldev->dmb_ht_lock);
> +		return -EINVAL;
> +	}
> +	hash_del(&dmb_node->list);
> +	write_unlock(&ldev->dmb_ht_lock);
> +
> +	clear_bit(dmb_node->sba_idx, ldev->sba_idx_mask);
> +	kfree(dmb_node->cpu_addr);
> +	kfree(dmb_node);
> +
> +	return 0;
> +}
> +
>   static int smc_lo_add_vlan_id(struct smcd_dev *smcd, u64 vlan_id)
>   {
>   	return -EOPNOTSUPP;
> @@ -76,6 +169,38 @@ static int smc_lo_signal_event(struct smcd_dev *dev, struct smcd_gid *rgid,
>   	return 0;
>   }
>   
> +static int smc_lo_move_data(struct smcd_dev *smcd, u64 dmb_tok,
> +			    unsigned int idx, bool sf, unsigned int offset,
> +			    void *data, unsigned int size)
> +{
> +	struct smc_lo_dmb_node *rmb_node = NULL, *tmp_node;
> +	struct smc_lo_dev *ldev = smcd->priv;
> +
> +	read_lock(&ldev->dmb_ht_lock);
> +	hash_for_each_possible(ldev->dmb_ht, tmp_node, list, dmb_tok) {
> +		if (tmp_node->token == dmb_tok) {
> +			rmb_node = tmp_node;
> +			break;
> +		}
> +	}
> +	if (!rmb_node) {
> +		read_unlock(&ldev->dmb_ht_lock);
> +		return -EINVAL;
> +	}
> +	read_unlock(&ldev->dmb_ht_lock);
> +
> +	memcpy((char *)rmb_node->cpu_addr + offset, data, size);
> +

Should this read_unlock be placed behind memcpy()?

<...>