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Received: from 30.221.128.233(mailfrom:guwen@linux.alibaba.com fp:SMTPD_---0W0uqlG1_1708394117) by smtp.aliyun-inc.com; Tue, 20 Feb 2024 09:55:18 +0800 Message-ID: Date: Tue, 20 Feb 2024 09:55:16 +0800 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net-next 06/15] net/smc: implement DMB-related operations of loopback-ism To: Wenjia Zhang , 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 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> From: Wen Gu In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 2024/2/16 22:13, Wenjia Zhang wrote: > > > 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 >> --- >>   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 >>   #include >> +#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_ht_lock won't be hold in an interrupt or sockirq context. The dmb_{register|unregister}, dmb_{attach|detach} and data_move are all on the process context. So I think write_(un)lock and read_(un)lock is safe here. >> +    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()? > dmb_ht_lock is used to ensure safe access to the DMB hash table of loopback-ism. The DMB hash table could be accessed by all the connections on loopback-ism, so it should be protected. But a certain DMB is only used by one connection, and the move_data process is protected by conn->send_lock (see smcd_tx_sndbuf_nonempty()), so the memcpy(rmb_node) here is safe and no race with other. Thanks! > <...>