[PATCH net-next 07/13] net/smc: delete an asymmetric link as SMC server

Karsten Graul
2020-05-02T12:36:18Z

When a link group moved from asymmetric to symmetric state then the
dangling asymmetric link can be deleted. Add smc_llc_find_asym_link() to
find the respective link and add smc_llc_delete_asym_link() to delete
it.

Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Reviewed-by: Ursula Braun <ubraun@linux.ibm.com>
---
net/smc/smc_llc.c | 81 ++++++++++++++++++++++++++++++++++++++++++++++-
net/smc/smc_wr.c | 2 +-
net/smc/smc_wr.h | 1 +
3 files changed, 82 insertions(+), 2 deletions(-)

diff --git a/net/smc/smc_llc.c b/net/smc/smc_llc.c
index 20ce29b88b50..e6e280a3683d 100644
--- a/net/smc/smc_llc.c
+++ b/net/smc/smc_llc.c
@@ -863,6 +863,85 @@ static void smc_llc_process_cli_add_link(struct smc_link_group *lgr)
mutex_unlock(&lgr->llc_conf_mutex);
}

+/* find the asymmetric link when 3 links are established */
+static struct smc_link *smc_llc_find_asym_link(struct smc_link_group *lgr)
+{
+ int asym_idx = -ENOENT;
+ int i, j, k;
+ bool found;
+
+ /* determine asymmetric link */
+ found = false;
+ for (i = 0; i < SMC_LINKS_PER_LGR_MAX; i++) {
+ for (j = i + 1; j < SMC_LINKS_PER_LGR_MAX; j++) {
+ if (!smc_link_usable(&lgr->lnk[i]) ||
+ !smc_link_usable(&lgr->lnk[j]))
+ continue;
+ if (!memcmp(lgr->lnk[i].gid, lgr->lnk[j].gid,
+ SMC_GID_SIZE)) {
+ found = true; /* asym_lnk is i or j */
+ break;
+ }
+ }
+ if (found)
+ break;
+ }
+ if (!found)
+ goto out; /* no asymmetric link */
+ for (k = 0; k < SMC_LINKS_PER_LGR_MAX; k++) {
+ if (!smc_link_usable(&lgr->lnk[k]))
+ continue;
+ if (k != i &&
+ !memcmp(lgr->lnk[i].peer_gid, lgr->lnk[k].peer_gid,
+ SMC_GID_SIZE)) {
+ asym_idx = i;
+ break;
+ }
+ if (k != j &&
+ !memcmp(lgr->lnk[j].peer_gid, lgr->lnk[k].peer_gid,
+ SMC_GID_SIZE)) {
+ asym_idx = j;
+ break;
+ }
+ }
+out:
+ return (asym_idx < 0) ? NULL : &lgr->lnk[asym_idx];
+}
+
+static void smc_llc_delete_asym_link(struct smc_link_group *lgr)
+{
+ struct smc_link *lnk_new = NULL, *lnk_asym;
+ struct smc_llc_qentry *qentry;
+ int rc;
+
+ lnk_asym = smc_llc_find_asym_link(lgr);
+ if (!lnk_asym)
+ return; /* no asymmetric link */
+ if (!smc_link_downing(&lnk_asym->state))
+ return;
+ /* tbd: lnk_new = smc_switch_conns(lgr, lnk_asym, false); */
+ smc_wr_tx_wait_no_pending_sends(lnk_asym);
+ if (!lnk_new)
+ goto out_free;
+ /* change flow type from ADD_LINK into DEL_LINK */
+ lgr->llc_flow_lcl.type = SMC_LLC_FLOW_DEL_LINK;
+ rc = smc_llc_send_delete_link(lnk_new, lnk_asym->link_id, SMC_LLC_REQ,
+ true, SMC_LLC_DEL_NO_ASYM_NEEDED);
+ if (rc) {
+ smcr_link_down_cond(lnk_new);
+ goto out_free;
+ }
+ qentry = smc_llc_wait(lgr, lnk_new, SMC_LLC_WAIT_TIME,
+ SMC_LLC_DELETE_LINK);
+ if (!qentry) {
+ smcr_link_down_cond(lnk_new);
+ goto out_free;
+ }
+ smc_llc_flow_qentry_del(&lgr->llc_flow_lcl);
+out_free:
+ smcr_link_clear(lnk_asym);
+}
+
static int smc_llc_srv_rkey_exchange(struct smc_link *link,
struct smc_link *link_new)
{
@@ -1014,7 +1093,7 @@ static void smc_llc_process_srv_add_link(struct smc_link_group *lgr)
rc = smc_llc_srv_add_link(link);
if (!rc && lgr->type == SMC_LGR_SYMMETRIC) {
/* delete any asymmetric link */
- /* tbd: smc_llc_delete_asym_link(lgr); */
+ smc_llc_delete_asym_link(lgr);
}
mutex_unlock(&lgr->llc_conf_mutex);
}
diff --git a/net/smc/smc_wr.c b/net/smc/smc_wr.c
index 031e6c9561b1..3fd27bea4f7a 100644
--- a/net/smc/smc_wr.c
+++ b/net/smc/smc_wr.c
@@ -61,7 +61,7 @@ static inline bool smc_wr_is_tx_pend(struct smc_link *link)
}

/* wait till all pending tx work requests on the given link are completed */
-static inline int smc_wr_tx_wait_no_pending_sends(struct smc_link *link)
+int smc_wr_tx_wait_no_pending_sends(struct smc_link *link)
{
if (wait_event_timeout(link->wr_tx_wait, !smc_wr_is_tx_pend(link),
SMC_WR_TX_WAIT_PENDING_TIME))
diff --git a/net/smc/smc_wr.h b/net/smc/smc_wr.h
index 3ac99c898418..f7eaeb3391f3 100644
--- a/net/smc/smc_wr.h
+++ b/net/smc/smc_wr.h
@@ -106,6 +106,7 @@ void smc_wr_tx_dismiss_slots(struct smc_link *lnk, u8 wr_rx_hdr_type,
smc_wr_tx_filter filter,
smc_wr_tx_dismisser dismisser,
unsigned long data);
+int smc_wr_tx_wait_no_pending_sends(struct smc_link *link);

int smc_wr_rx_register_handler(struct smc_wr_rx_handler *handler);
int smc_wr_rx_post_init(struct smc_link *link);
--
2.17.1