net/smc: improved fix wait on already cleared link

Commit 8f3d65c16679 ("net/smc: fix wait on already cleared link")
introduced link refcounting to avoid waits on already cleared links.
This patch extents and improves the refcounting to cover all
remaining possible cases for this kind of error situation.

Fixes: 15e1b99aadfb ("net/smc: no WR buffer wait for terminating link group")
Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/smc/smc_cdc.c b/net/smc/smc_cdc.c
index f23f558054a7cba4fa29e430bbd6729074a55611..99acd337ba90d828c6f11099fe2a54ac91055eaa 100644 (file)
--- a/net/smc/smc_cdc.c
+++ b/net/smc/smc_cdc.c
@@ -150,9 +150,11 @@ static int smcr_cdc_get_slot_and_msg_send(struct smc_connection *conn)
 
 again:
        link = conn->lnk;
+       if (!smc_wr_tx_link_hold(link))
+               return -ENOLINK;
        rc = smc_cdc_get_free_slot(conn, link, &wr_buf, NULL, &pend);
        if (rc)
-               return rc;
+               goto put_out;
 
        spin_lock_bh(&conn->send_lock);
        if (link != conn->lnk) {
@@ -160,6 +162,7 @@ again:
                spin_unlock_bh(&conn->send_lock);
                smc_wr_tx_put_slot(link,
                                   (struct smc_wr_tx_pend_priv *)pend);
+               smc_wr_tx_link_put(link);
                if (again)
                        return -ENOLINK;
                again = true;
@@ -167,6 +170,8 @@ again:
        }
        rc = smc_cdc_msg_send(conn, wr_buf, pend);
        spin_unlock_bh(&conn->send_lock);
+put_out:
+       smc_wr_tx_link_put(link);
        return rc;
 }
 

diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c
index 8280c938be80102afa7c6770dc4946d9fed0f053..d2206743dc714863472f23a0cf70166569491ca0 100644 (file)
--- a/net/smc/smc_core.c
+++ b/net/smc/smc_core.c
@@ -949,7 +949,7 @@ struct smc_link *smc_switch_conns(struct smc_link_group *lgr,
                to_lnk = &lgr->lnk[i];
                break;
        }
-       if (!to_lnk) {
+       if (!to_lnk || !smc_wr_tx_link_hold(to_lnk)) {
                smc_lgr_terminate_sched(lgr);
                return NULL;
        }
@@ -981,24 +981,26 @@ again:
                read_unlock_bh(&lgr->conns_lock);
                /* pre-fetch buffer outside of send_lock, might sleep */
                rc = smc_cdc_get_free_slot(conn, to_lnk, &wr_buf, NULL, &pend);
-               if (rc) {
-                       smcr_link_down_cond_sched(to_lnk);
-                       return NULL;
-               }
+               if (rc)
+                       goto err_out;
                /* avoid race with smcr_tx_sndbuf_nonempty() */
                spin_lock_bh(&conn->send_lock);
                smc_switch_link_and_count(conn, to_lnk);
                rc = smc_switch_cursor(smc, pend, wr_buf);
                spin_unlock_bh(&conn->send_lock);
                sock_put(&smc->sk);
-               if (rc) {
-                       smcr_link_down_cond_sched(to_lnk);
-                       return NULL;
-               }
+               if (rc)
+                       goto err_out;
                goto again;
        }
        read_unlock_bh(&lgr->conns_lock);
+       smc_wr_tx_link_put(to_lnk);
        return to_lnk;
+
+err_out:
+       smcr_link_down_cond_sched(to_lnk);
+       smc_wr_tx_link_put(to_lnk);
+       return NULL;
 }
 
 static void smcr_buf_unuse(struct smc_buf_desc *rmb_desc,

diff --git a/net/smc/smc_llc.c b/net/smc/smc_llc.c
index 2e7560eba9812635c22f18f41aafc38b063dd02a..72f4b72eb1753a899f164e10aa1e75620c7e5bfa 100644 (file)
--- a/net/smc/smc_llc.c
+++ b/net/smc/smc_llc.c
@@ -383,9 +383,11 @@ int smc_llc_send_confirm_link(struct smc_link *link,
        struct smc_wr_buf *wr_buf;
        int rc;
 
+       if (!smc_wr_tx_link_hold(link))
+               return -ENOLINK;
        rc = smc_llc_add_pending_send(link, &wr_buf, &pend);
        if (rc)
-               return rc;
+               goto put_out;
        confllc = (struct smc_llc_msg_confirm_link *)wr_buf;
        memset(confllc, 0, sizeof(*confllc));
        confllc->hd.common.type = SMC_LLC_CONFIRM_LINK;
@@ -402,6 +404,8 @@ int smc_llc_send_confirm_link(struct smc_link *link,
        confllc->max_links = SMC_LLC_ADD_LNK_MAX_LINKS;
        /* send llc message */
        rc = smc_wr_tx_send(link, pend);
+put_out:
+       smc_wr_tx_link_put(link);
        return rc;
 }
 
@@ -415,9 +419,11 @@ static int smc_llc_send_confirm_rkey(struct smc_link *send_link,
        struct smc_link *link;
        int i, rc, rtok_ix;
 
+       if (!smc_wr_tx_link_hold(send_link))
+               return -ENOLINK;
        rc = smc_llc_add_pending_send(send_link, &wr_buf, &pend);
        if (rc)
-               return rc;
+               goto put_out;
        rkeyllc = (struct smc_llc_msg_confirm_rkey *)wr_buf;
        memset(rkeyllc, 0, sizeof(*rkeyllc));
        rkeyllc->hd.common.type = SMC_LLC_CONFIRM_RKEY;
@@ -444,6 +450,8 @@ static int smc_llc_send_confirm_rkey(struct smc_link *send_link,
                (u64)sg_dma_address(rmb_desc->sgt[send_link->link_idx].sgl));
        /* send llc message */
        rc = smc_wr_tx_send(send_link, pend);
+put_out:
+       smc_wr_tx_link_put(send_link);
        return rc;
 }
 
@@ -456,9 +464,11 @@ static int smc_llc_send_delete_rkey(struct smc_link *link,
        struct smc_wr_buf *wr_buf;
        int rc;
 
+       if (!smc_wr_tx_link_hold(link))
+               return -ENOLINK;
        rc = smc_llc_add_pending_send(link, &wr_buf, &pend);
        if (rc)
-               return rc;
+               goto put_out;
        rkeyllc = (struct smc_llc_msg_delete_rkey *)wr_buf;
        memset(rkeyllc, 0, sizeof(*rkeyllc));
        rkeyllc->hd.common.type = SMC_LLC_DELETE_RKEY;
@@ -467,6 +477,8 @@ static int smc_llc_send_delete_rkey(struct smc_link *link,
        rkeyllc->rkey[0] = htonl(rmb_desc->mr_rx[link->link_idx]->rkey);
        /* send llc message */
        rc = smc_wr_tx_send(link, pend);
+put_out:
+       smc_wr_tx_link_put(link);
        return rc;
 }
 
@@ -480,9 +492,11 @@ int smc_llc_send_add_link(struct smc_link *link, u8 mac[], u8 gid[],
        struct smc_wr_buf *wr_buf;
        int rc;
 
+       if (!smc_wr_tx_link_hold(link))
+               return -ENOLINK;
        rc = smc_llc_add_pending_send(link, &wr_buf, &pend);
        if (rc)
-               return rc;
+               goto put_out;
        addllc = (struct smc_llc_msg_add_link *)wr_buf;
 
        memset(addllc, 0, sizeof(*addllc));
@@ -504,6 +518,8 @@ int smc_llc_send_add_link(struct smc_link *link, u8 mac[], u8 gid[],
        }
        /* send llc message */
        rc = smc_wr_tx_send(link, pend);
+put_out:
+       smc_wr_tx_link_put(link);
        return rc;
 }
 
@@ -517,9 +533,11 @@ int smc_llc_send_delete_link(struct smc_link *link, u8 link_del_id,
        struct smc_wr_buf *wr_buf;
        int rc;
 
+       if (!smc_wr_tx_link_hold(link))
+               return -ENOLINK;
        rc = smc_llc_add_pending_send(link, &wr_buf, &pend);
        if (rc)
-               return rc;
+               goto put_out;
        delllc = (struct smc_llc_msg_del_link *)wr_buf;
 
        memset(delllc, 0, sizeof(*delllc));
@@ -536,6 +554,8 @@ int smc_llc_send_delete_link(struct smc_link *link, u8 link_del_id,
        delllc->reason = htonl(reason);
        /* send llc message */
        rc = smc_wr_tx_send(link, pend);
+put_out:
+       smc_wr_tx_link_put(link);
        return rc;
 }
 
@@ -547,9 +567,11 @@ static int smc_llc_send_test_link(struct smc_link *link, u8 user_data[16])
        struct smc_wr_buf *wr_buf;
        int rc;
 
+       if (!smc_wr_tx_link_hold(link))
+               return -ENOLINK;
        rc = smc_llc_add_pending_send(link, &wr_buf, &pend);
        if (rc)
-               return rc;
+               goto put_out;
        testllc = (struct smc_llc_msg_test_link *)wr_buf;
        memset(testllc, 0, sizeof(*testllc));
        testllc->hd.common.type = SMC_LLC_TEST_LINK;
@@ -557,6 +579,8 @@ static int smc_llc_send_test_link(struct smc_link *link, u8 user_data[16])
        memcpy(testllc->user_data, user_data, sizeof(testllc->user_data));
        /* send llc message */
        rc = smc_wr_tx_send(link, pend);
+put_out:
+       smc_wr_tx_link_put(link);
        return rc;
 }
 
@@ -567,13 +591,16 @@ static int smc_llc_send_message(struct smc_link *link, void *llcbuf)
        struct smc_wr_buf *wr_buf;
        int rc;
 
-       if (!smc_link_usable(link))
+       if (!smc_wr_tx_link_hold(link))
                return -ENOLINK;
        rc = smc_llc_add_pending_send(link, &wr_buf, &pend);
        if (rc)
-               return rc;
+               goto put_out;
        memcpy(wr_buf, llcbuf, sizeof(union smc_llc_msg));
-       return smc_wr_tx_send(link, pend);
+       rc = smc_wr_tx_send(link, pend);
+put_out:
+       smc_wr_tx_link_put(link);
+       return rc;
 }
 
 /* schedule an llc send on link, may wait for buffers,
@@ -586,13 +613,16 @@ static int smc_llc_send_message_wait(struct smc_link *link, void *llcbuf)
        struct smc_wr_buf *wr_buf;
        int rc;
 
-       if (!smc_link_usable(link))
+       if (!smc_wr_tx_link_hold(link))
                return -ENOLINK;
        rc = smc_llc_add_pending_send(link, &wr_buf, &pend);
        if (rc)
-               return rc;
+               goto put_out;
        memcpy(wr_buf, llcbuf, sizeof(union smc_llc_msg));
-       return smc_wr_tx_send_wait(link, pend, SMC_LLC_WAIT_TIME);
+       rc = smc_wr_tx_send_wait(link, pend, SMC_LLC_WAIT_TIME);
+put_out:
+       smc_wr_tx_link_put(link);
+       return rc;
 }
 
 /********************************* receive ***********************************/
@@ -672,9 +702,11 @@ static int smc_llc_add_link_cont(struct smc_link *link,
        struct smc_buf_desc *rmb;
        u8 n;
 
+       if (!smc_wr_tx_link_hold(link))
+               return -ENOLINK;
        rc = smc_llc_add_pending_send(link, &wr_buf, &pend);
        if (rc)
-               return rc;
+               goto put_out;
        addc_llc = (struct smc_llc_msg_add_link_cont *)wr_buf;
        memset(addc_llc, 0, sizeof(*addc_llc));
 
@@ -706,7 +738,10 @@ static int smc_llc_add_link_cont(struct smc_link *link,
        addc_llc->hd.length = sizeof(struct smc_llc_msg_add_link_cont);
        if (lgr->role == SMC_CLNT)
                addc_llc->hd.flags |= SMC_LLC_FLAG_RESP;
-       return smc_wr_tx_send(link, pend);
+       rc = smc_wr_tx_send(link, pend);
+put_out:
+       smc_wr_tx_link_put(link);
+       return rc;
 }
 
 static int smc_llc_cli_rkey_exchange(struct smc_link *link,

diff --git a/net/smc/smc_tx.c b/net/smc/smc_tx.c
index c79361dfcdfb9f21d9541a7249b84227ca603b38..738a4a99c82797b7b5d28afaba5208135e1983ad 100644 (file)
--- a/net/smc/smc_tx.c
+++ b/net/smc/smc_tx.c
@@ -496,7 +496,7 @@ static int smc_tx_rdma_writes(struct smc_connection *conn,
 /* Wakeup sndbuf consumers from any context (IRQ or process)
  * since there is more data to transmit; usable snd_wnd as max transmit
  */
-static int _smcr_tx_sndbuf_nonempty(struct smc_connection *conn)
+static int smcr_tx_sndbuf_nonempty(struct smc_connection *conn)
 {
        struct smc_cdc_producer_flags *pflags = &conn->local_tx_ctrl.prod_flags;
        struct smc_link *link = conn->lnk;
@@ -505,8 +505,11 @@ static int _smcr_tx_sndbuf_nonempty(struct smc_connection *conn)
        struct smc_wr_buf *wr_buf;
        int rc;
 
+       if (!link || !smc_wr_tx_link_hold(link))
+               return -ENOLINK;
        rc = smc_cdc_get_free_slot(conn, link, &wr_buf, &wr_rdma_buf, &pend);
        if (rc < 0) {
+               smc_wr_tx_link_put(link);
                if (rc == -EBUSY) {
                        struct smc_sock *smc =
                                container_of(conn, struct smc_sock, conn);
@@ -547,22 +550,7 @@ static int _smcr_tx_sndbuf_nonempty(struct smc_connection *conn)
 
 out_unlock:
        spin_unlock_bh(&conn->send_lock);
-       return rc;
-}
-
-static int smcr_tx_sndbuf_nonempty(struct smc_connection *conn)
-{
-       struct smc_link *link = conn->lnk;
-       int rc = -ENOLINK;
-
-       if (!link)
-               return rc;
-
-       atomic_inc(&link->wr_tx_refcnt);
-       if (smc_link_usable(link))
-               rc = _smcr_tx_sndbuf_nonempty(conn);
-       if (atomic_dec_and_test(&link->wr_tx_refcnt))
-               wake_up_all(&link->wr_tx_wait);
+       smc_wr_tx_link_put(link);
        return rc;
 }
 

diff --git a/net/smc/smc_wr.h b/net/smc/smc_wr.h
index 423b8709f1c9e4fd2462dc2bb929ebc24e01f454..2bc626f230a56dca33fb5617972443c8aecf98ee 100644 (file)
--- a/net/smc/smc_wr.h
+++ b/net/smc/smc_wr.h
@@ -60,6 +60,20 @@ static inline void smc_wr_tx_set_wr_id(atomic_long_t *wr_tx_id, long val)
        atomic_long_set(wr_tx_id, val);
 }
 
+static inline bool smc_wr_tx_link_hold(struct smc_link *link)
+{
+       if (!smc_link_usable(link))
+               return false;
+       atomic_inc(&link->wr_tx_refcnt);
+       return true;
+}
+
+static inline void smc_wr_tx_link_put(struct smc_link *link)
+{
+       if (atomic_dec_and_test(&link->wr_tx_refcnt))
+               wake_up_all(&link->wr_tx_wait);
+}
+
 static inline void smc_wr_wakeup_tx_wait(struct smc_link *lnk)
 {
        wake_up_all(&lnk->wr_tx_wait);