Re: [RFC PATCH net-next v5 4/9] net/smc: Introduce SMC-D loopback device

Simon Horman
2023-04-28T14:45:22Z

On Sun, Apr 23, 2023 at 08:17:46PM +0800, Wen Gu wrote:
> This patch introduces a kind of loopback device for SMC-D, thus
> enabling the SMC communication between two local sockets within
> one OS instance.
>
> The loopback device supports basic capabilities defined by SMC-D
> options, and exposed as an SMC-D v2 device.
>
> The GID of loopback device is random generated, CHID is 0xFFFF
> and SEID is SMCD_DEFAULT_V2_SEID.
>
> TODO:
> - The hierarchy preference of coexistent SMC-D devices.
>
> Signed-off-by: Wen Gu <guwen@linux.alibaba.com>
> ---
> include/net/smc.h | 6 +
> net/smc/Makefile | 2 +-
> net/smc/af_smc.c | 12 +-
> net/smc/smc_cdc.c | 9 +-
> net/smc/smc_cdc.h | 1 +
> net/smc/smc_ism.h | 2 +
> net/smc/smc_loopback.c | 406 +++++++++++++++++++++++++++++++++++++++++++++++++
> net/smc/smc_loopback.h | 51 +++++++
> 8 files changed, 486 insertions(+), 3 deletions(-)
> create mode 100644 net/smc/smc_loopback.c
> create mode 100644 net/smc/smc_loopback.h
>
> diff --git a/include/net/smc.h b/include/net/smc.h
> index 26206d2..021ca42 100644
> --- a/include/net/smc.h
> +++ b/include/net/smc.h
> @@ -41,6 +41,12 @@ struct smcd_dmb {
> dma_addr_t dma_addr;
> };
>
> +struct smcd_seid {
> + u8 seid_string[24];
> + u8 serial_number[4];
> + u8 type[4];
> +};
> +
> #define ISM_EVENT_DMB 0
> #define ISM_EVENT_GID 1
> #define ISM_EVENT_SWR 2
> diff --git a/net/smc/Makefile b/net/smc/Makefile
> index 875efcd..a8c3711 100644
> --- a/net/smc/Makefile
> +++ b/net/smc/Makefile
> @@ -4,5 +4,5 @@ obj-$(CONFIG_SMC) += smc.o
> obj-$(CONFIG_SMC_DIAG) += smc_diag.o
> smc-y := af_smc.o smc_pnet.o smc_ib.o smc_clc.o smc_core.o smc_wr.o smc_llc.o
> smc-y += smc_cdc.o smc_tx.o smc_rx.o smc_close.o smc_ism.o smc_netlink.o smc_stats.o
> -smc-y += smc_tracepoint.o
> +smc-y += smc_tracepoint.o smc_loopback.o
> smc-$(CONFIG_SYSCTL) += smc_sysctl.o
> diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
> index 50c38b6..3230309 100644
> --- a/net/smc/af_smc.c
> +++ b/net/smc/af_smc.c
> @@ -53,6 +53,7 @@
> #include "smc_stats.h"
> #include "smc_tracepoint.h"
> #include "smc_sysctl.h"
> +#include "smc_loopback.h"
>
> static DEFINE_MUTEX(smc_server_lgr_pending); /* serialize link group
> * creation on server
> @@ -3482,15 +3483,23 @@ static int __init smc_init(void)
> goto out_sock;
> }
>
> + rc = smc_loopback_init();
> + if (rc) {
> + pr_err("%s: smc_loopback_init fails with %d\n", __func__, rc);
> + goto out_ib;
> + }
> +
> rc = tcp_register_ulp(&smc_ulp_ops);
> if (rc) {
> pr_err("%s: tcp_ulp_register fails with %d\n", __func__, rc);
> - goto out_ib;
> + goto out_lo;
> }
>
> static_branch_enable(&tcp_have_smc);
> return 0;
>
> +out_lo:
> + smc_loopback_exit();
> out_ib:
> smc_ib_unregister_client();
> out_sock:
> @@ -3528,6 +3537,7 @@ static void __exit smc_exit(void)
> tcp_unregister_ulp(&smc_ulp_ops);
> sock_unregister(PF_SMC);
> smc_core_exit();
> + smc_loopback_exit();
> smc_ib_unregister_client();
> smc_ism_exit();
> destroy_workqueue(smc_close_wq);
> diff --git a/net/smc/smc_cdc.c b/net/smc/smc_cdc.c
> index 89105e9..2f79bac 100644
> --- a/net/smc/smc_cdc.c
> +++ b/net/smc/smc_cdc.c
> @@ -410,7 +410,14 @@ 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);
> + struct smc_connection *conn =
> + from_tasklet(conn, t, rx_tsklet);

nit: I think the above can be on one line, as it was before this patch.

> +
> + 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 696cc11..11559d4 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_ism.h b/net/smc/smc_ism.h
> index 14d2e77..d18c50a 100644
> --- a/net/smc/smc_ism.h
> +++ b/net/smc/smc_ism.h
> @@ -15,6 +15,8 @@
>
> #include "smc.h"
>
> +#define S390_ISM_IDENT_MASK 0x00FFFF

nit: I think GENMASK is appropriate here.

> +
> struct smcd_dev_list { /* List of SMCD devices */
> struct list_head list;
> struct mutex mutex; /* Protects list of devices */

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