net/smc: use a workqueue to defer llc send

SMC handles deferred work in tasklets. As tasklets cannot sleep this
can result in rare EBUSY conditions, so defer this work in a work queue.
The high level api functions do not defer work because they can sleep
until the llc send is actually completed.

Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: Ursula Braun <ubraun@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c
index ba7dae8..4523bba 100644 (file)
--- a/net/smc/smc_core.c
+++ b/net/smc/smc_core.c
@@ -194,10 +194,12 @@ static int smc_lgr_create(struct smc_sock *smc,
                smc_ib_setup_per_ibdev(smcibdev);
        get_random_bytes(rndvec, sizeof(rndvec));
        lnk->psn_initial = rndvec[0] + (rndvec[1] << 8) + (rndvec[2] << 16);
-       smc_llc_link_init(lnk);
-       rc = smc_wr_alloc_link_mem(lnk);
+       rc = smc_llc_link_init(lnk);
        if (rc)
                goto free_lgr;
+       rc = smc_wr_alloc_link_mem(lnk);
+       if (rc)
+               goto clear_llc_lnk;
        rc = smc_ib_create_protection_domain(lnk);
        if (rc)
                goto free_link_mem;
@@ -221,6 +223,8 @@ dealloc_pd:
        smc_ib_dealloc_protection_domain(lnk);
 free_link_mem:
        smc_wr_free_link_mem(lnk);
+clear_llc_lnk:
+       smc_llc_link_clear(lnk);
 free_lgr:
        kfree(lgr);
 out:
@@ -266,6 +270,7 @@ void smc_conn_free(struct smc_connection *conn)
 static void smc_link_clear(struct smc_link *lnk)
 {
        lnk->peer_qpn = 0;
+       smc_llc_link_clear(lnk);
        smc_ib_modify_qp_reset(lnk);
        smc_wr_free_link(lnk);
        smc_ib_destroy_queue_pair(lnk);
@@ -323,7 +328,6 @@ static void smc_lgr_free_bufs(struct smc_link_group *lgr)
 /* remove a link group */
 void smc_lgr_free(struct smc_link_group *lgr)
 {
-       smc_llc_link_flush(&lgr->lnk[SMC_SINGLE_LINK]);
        smc_lgr_free_bufs(lgr);
        smc_link_clear(&lgr->lnk[SMC_SINGLE_LINK]);
        kfree(lgr);

diff --git a/net/smc/smc_core.h b/net/smc/smc_core.h
index 9398e23..d175385 100644 (file)
--- a/net/smc/smc_core.h
+++ b/net/smc/smc_core.h
@@ -96,6 +96,7 @@ struct smc_link {
        u8                      link_id;        /* unique # within link group */
 
        enum smc_link_state     state;          /* state of link */
+       struct workqueue_struct *llc_wq;        /* single thread work queue */
        struct completion       llc_confirm;    /* wait for rx of conf link */
        struct completion       llc_confirm_resp; /* wait 4 rx of cnf lnk rsp */
        int                     llc_confirm_rc; /* rc from confirm link msg */

diff --git a/net/smc/smc_llc.c b/net/smc/smc_llc.c
index 5dbeced..5d7926c 100644 (file)
--- a/net/smc/smc_llc.c
+++ b/net/smc/smc_llc.c
@@ -239,6 +239,25 @@ static int smc_llc_send_confirm_rkey(struct smc_link *link,
        return rc;
 }
 
+/* prepare an add link message */
+static void smc_llc_prep_add_link(struct smc_llc_msg_add_link *addllc,
+                                 struct smc_link *link, u8 mac[],
+                                 union ib_gid *gid,
+                                 enum smc_llc_reqresp reqresp)
+{
+       memset(addllc, 0, sizeof(*addllc));
+       addllc->hd.common.type = SMC_LLC_ADD_LINK;
+       addllc->hd.length = sizeof(struct smc_llc_msg_add_link);
+       if (reqresp == SMC_LLC_RESP) {
+               addllc->hd.flags |= SMC_LLC_FLAG_RESP;
+               /* always reject more links for now */
+               addllc->hd.flags |= SMC_LLC_FLAG_ADD_LNK_REJ;
+               addllc->hd.add_link_rej_rsn = SMC_LLC_REJ_RSN_NO_ALT_PATH;
+       }
+       memcpy(addllc->sender_mac, mac, ETH_ALEN);
+       memcpy(addllc->sender_gid, gid, SMC_GID_SIZE);
+}
+
 /* send ADD LINK request or response */
 int smc_llc_send_add_link(struct smc_link *link, u8 mac[],
                          union ib_gid *gid,
@@ -253,22 +272,28 @@ int smc_llc_send_add_link(struct smc_link *link, u8 mac[],
        if (rc)
                return rc;
        addllc = (struct smc_llc_msg_add_link *)wr_buf;
-       memset(addllc, 0, sizeof(*addllc));
-       addllc->hd.common.type = SMC_LLC_ADD_LINK;
-       addllc->hd.length = sizeof(struct smc_llc_msg_add_link);
-       if (reqresp == SMC_LLC_RESP) {
-               addllc->hd.flags |= SMC_LLC_FLAG_RESP;
-               /* always reject more links for now */
-               addllc->hd.flags |= SMC_LLC_FLAG_ADD_LNK_REJ;
-               addllc->hd.add_link_rej_rsn = SMC_LLC_REJ_RSN_NO_ALT_PATH;
-       }
-       memcpy(addllc->sender_mac, mac, ETH_ALEN);
-       memcpy(addllc->sender_gid, gid, SMC_GID_SIZE);
+       smc_llc_prep_add_link(addllc, link, mac, gid, reqresp);
        /* send llc message */
        rc = smc_wr_tx_send(link, pend);
        return rc;
 }
 
+/* prepare a delete link message */
+static void smc_llc_prep_delete_link(struct smc_llc_msg_del_link *delllc,
+                                    struct smc_link *link,
+                                    enum smc_llc_reqresp reqresp)
+{
+       memset(delllc, 0, sizeof(*delllc));
+       delllc->hd.common.type = SMC_LLC_DELETE_LINK;
+       delllc->hd.length = sizeof(struct smc_llc_msg_add_link);
+       if (reqresp == SMC_LLC_RESP)
+               delllc->hd.flags |= SMC_LLC_FLAG_RESP;
+       /* DEL_LINK_ALL because only 1 link supported */
+       delllc->hd.flags |= SMC_LLC_FLAG_DEL_LINK_ALL;
+       delllc->hd.flags |= SMC_LLC_FLAG_DEL_LINK_ORDERLY;
+       delllc->link_num = link->link_id;
+}
+
 /* send DELETE LINK request or response */
 int smc_llc_send_delete_link(struct smc_link *link,
                             enum smc_llc_reqresp reqresp)
@@ -282,15 +307,7 @@ int smc_llc_send_delete_link(struct smc_link *link,
        if (rc)
                return rc;
        delllc = (struct smc_llc_msg_del_link *)wr_buf;
-       memset(delllc, 0, sizeof(*delllc));
-       delllc->hd.common.type = SMC_LLC_DELETE_LINK;
-       delllc->hd.length = sizeof(struct smc_llc_msg_add_link);
-       if (reqresp == SMC_LLC_RESP)
-               delllc->hd.flags |= SMC_LLC_FLAG_RESP;
-       /* DEL_LINK_ALL because only 1 link supported */
-       delllc->hd.flags |= SMC_LLC_FLAG_DEL_LINK_ALL;
-       delllc->hd.flags |= SMC_LLC_FLAG_DEL_LINK_ORDERLY;
-       delllc->link_num = link->link_id;
+       smc_llc_prep_delete_link(delllc, link, reqresp);
        /* send llc message */
        rc = smc_wr_tx_send(link, pend);
        return rc;
@@ -317,20 +334,46 @@ static int smc_llc_send_test_link(struct smc_link *link, u8 user_data[16])
        return rc;
 }
 
-/* send a prepared message */
-static int smc_llc_send_message(struct smc_link *link, void *llcbuf, int llclen)
+struct smc_llc_send_work {
+       struct work_struct work;
+       struct smc_link *link;
+       int llclen;
+       union smc_llc_msg llcbuf;
+};
+
+/* worker that sends a prepared message */
+static void smc_llc_send_message_work(struct work_struct *work)
 {
+       struct smc_llc_send_work *llcwrk = container_of(work,
+                                               struct smc_llc_send_work, work);
        struct smc_wr_tx_pend_priv *pend;
        struct smc_wr_buf *wr_buf;
        int rc;
 
-       rc = smc_llc_add_pending_send(link, &wr_buf, &pend);
+       if (llcwrk->link->state == SMC_LNK_INACTIVE)
+               goto out;
+       rc = smc_llc_add_pending_send(llcwrk->link, &wr_buf, &pend);
        if (rc)
-               return rc;
-       memcpy(wr_buf, llcbuf, llclen);
-       /* send llc message */
-       rc = smc_wr_tx_send(link, pend);
-       return rc;
+               goto out;
+       memcpy(wr_buf, &llcwrk->llcbuf, llcwrk->llclen);
+       smc_wr_tx_send(llcwrk->link, pend);
+out:
+       kfree(llcwrk);
+}
+
+/* copy llcbuf and schedule an llc send on link */
+static int smc_llc_send_message(struct smc_link *link, void *llcbuf, int llclen)
+{
+       struct smc_llc_send_work *wrk = kmalloc(sizeof(*wrk), GFP_ATOMIC);
+
+       if (!wrk)
+               return -ENOMEM;
+       INIT_WORK(&wrk->work, smc_llc_send_message_work);
+       wrk->link = link;
+       wrk->llclen = llclen;
+       memcpy(&wrk->llcbuf, llcbuf, llclen);
+       queue_work(link->llc_wq, &wrk->work);
+       return 0;
 }
 
 /********************************* receive ***********************************/
@@ -381,17 +424,18 @@ static void smc_llc_rx_add_link(struct smc_link *link,
                }
 
                if (lgr->role == SMC_SERV) {
-                       smc_llc_send_add_link(link,
+                       smc_llc_prep_add_link(llc, link,
                                        link->smcibdev->mac[link->ibport - 1],
                                        &link->smcibdev->gid[link->ibport - 1],
                                        SMC_LLC_REQ);
 
                } else {
-                       smc_llc_send_add_link(link,
+                       smc_llc_prep_add_link(llc, link,
                                        link->smcibdev->mac[link->ibport - 1],
                                        &link->smcibdev->gid[link->ibport - 1],
                                        SMC_LLC_RESP);
                }
+               smc_llc_send_message(link, llc, sizeof(*llc));
        }
 }
 
@@ -407,9 +451,11 @@ static void smc_llc_rx_delete_link(struct smc_link *link,
        } else {
                if (lgr->role == SMC_SERV) {
                        smc_lgr_forget(lgr);
-                       smc_llc_send_delete_link(link, SMC_LLC_REQ);
+                       smc_llc_prep_delete_link(llc, link, SMC_LLC_REQ);
+                       smc_llc_send_message(link, llc, sizeof(*llc));
                } else {
-                       smc_llc_send_delete_link(link, SMC_LLC_RESP);
+                       smc_llc_prep_delete_link(llc, link, SMC_LLC_RESP);
+                       smc_llc_send_message(link, llc, sizeof(*llc));
                        smc_lgr_terminate(lgr);
                }
        }
@@ -559,11 +605,19 @@ static void smc_llc_testlink_work(struct work_struct *work)
        }
        next_interval = link->llc_testlink_time;
 out:
-       schedule_delayed_work(&link->llc_testlink_wrk, next_interval);
+       queue_delayed_work(link->llc_wq, &link->llc_testlink_wrk,
+                          next_interval);
 }
 
-void smc_llc_link_init(struct smc_link *link)
+int smc_llc_link_init(struct smc_link *link)
 {
+       struct smc_link_group *lgr = container_of(link, struct smc_link_group,
+                                                 lnk[SMC_SINGLE_LINK]);
+       link->llc_wq = alloc_ordered_workqueue("llc_wq-%x:%x)", WQ_MEM_RECLAIM,
+                                              *((u32 *)lgr->id),
+                                              link->link_id);
+       if (!link->llc_wq)
+               return -ENOMEM;
        init_completion(&link->llc_confirm);
        init_completion(&link->llc_confirm_resp);
        init_completion(&link->llc_add);
@@ -571,6 +625,7 @@ void smc_llc_link_init(struct smc_link *link)
        init_completion(&link->llc_confirm_rkey);
        init_completion(&link->llc_testlink_resp);
        INIT_DELAYED_WORK(&link->llc_testlink_wrk, smc_llc_testlink_work);
+       return 0;
 }
 
 void smc_llc_link_active(struct smc_link *link, int testlink_time)
@@ -578,8 +633,8 @@ void smc_llc_link_active(struct smc_link *link, int testlink_time)
        link->state = SMC_LNK_ACTIVE;
        if (testlink_time) {
                link->llc_testlink_time = testlink_time * HZ;
-               schedule_delayed_work(&link->llc_testlink_wrk,
-                                     link->llc_testlink_time);
+               queue_delayed_work(link->llc_wq, &link->llc_testlink_wrk,
+                                  link->llc_testlink_time);
        }
 }
 
@@ -591,9 +646,10 @@ void smc_llc_link_inactive(struct smc_link *link)
 }
 
 /* called in worker context */
-void smc_llc_link_flush(struct smc_link *link)
+void smc_llc_link_clear(struct smc_link *link)
 {
-       cancel_delayed_work_sync(&link->llc_testlink_wrk);
+       flush_workqueue(link->llc_wq);
+       destroy_workqueue(link->llc_wq);
 }
 
 /* register a new rtoken at the remote peer */

diff --git a/net/smc/smc_llc.h b/net/smc/smc_llc.h
index d7f52a6..65c8645 100644 (file)
--- a/net/smc/smc_llc.h
+++ b/net/smc/smc_llc.h
@@ -42,10 +42,10 @@ int smc_llc_send_add_link(struct smc_link *link, u8 mac[], union ib_gid *gid,
                          enum smc_llc_reqresp reqresp);
 int smc_llc_send_delete_link(struct smc_link *link,
                             enum smc_llc_reqresp reqresp);
-void smc_llc_link_init(struct smc_link *link);
+int smc_llc_link_init(struct smc_link *link);
 void smc_llc_link_active(struct smc_link *link, int testlink_time);
 void smc_llc_link_inactive(struct smc_link *link);
-void smc_llc_link_flush(struct smc_link *link);
+void smc_llc_link_clear(struct smc_link *link);
 int smc_llc_do_confirm_rkey(struct smc_link *link,
                            struct smc_buf_desc *rmb_desc);
 int smc_llc_init(void) __init;