[PATCH net-next 06/10] net/smc: use a workqueue to defer llc send

Ursula Braun
2018-05-15T15:04:59Z

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>
---
net/smc/smc_core.c | 10 ++--
net/smc/smc_core.h | 1 +
net/smc/smc_llc.c | 132 ++++++++++++++++++++++++++++++++++++++---------------
net/smc/smc_llc.h | 4 +-
4 files changed, 104 insertions(+), 43 deletions(-)

diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c
index ba7dae819ac8..4523bbad8a15 100644
--- 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 @@ static int smc_lgr_create(struct smc_sock *smc,
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 9398e235d74b..d1753850684b 100644
--- 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 5dbeced6cea5..5d7926cc472c 100644
--- 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 d7f52a60c8d6..65c8645e96a1 100644
--- 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;
--
2.16.3