Merge branch 'net-smc-fixes-2020-10-14'

Karsten Graul says:

====================
net/smc: fixes 2020-10-14

The first patch fixes a possible use-after-free of delayed llc events.
Patch 2 corrects the number of DMB buffer sizes. And patch 3 ensures
a correctly formatted return code when smc_ism_register_dmb() fails to
create a new DMB.
====================

Link: https://lore.kernel.org/r/20201014174329.35791-1-kgraul@linux.ibm.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/smc/smc_core.c

@@ -1597,7 +1597,7 @@ static int smcr_buf_map_usable_links(struct smc_link_group *lgr,
 	return rc;
 }
 
-#define SMCD_DMBE_SIZES		7 /* 0 -> 16KB, 1 -> 32KB, .. 6 -> 1MB */
+#define SMCD_DMBE_SIZES		6 /* 0 -> 16KB, 1 -> 32KB, .. 6 -> 1MB */
 
 static struct smc_buf_desc *smcd_new_buf_create(struct smc_link_group *lgr,
 						bool is_dmb, int bufsize)
@@ -1616,7 +1616,8 @@ static struct smc_buf_desc *smcd_new_buf_create(struct smc_link_group *lgr,
 		rc = smc_ism_register_dmb(lgr, bufsize, buf_desc);
 		if (rc) {
 			kfree(buf_desc);
-			return (rc == -ENOMEM) ? ERR_PTR(-EAGAIN) : ERR_PTR(rc);
+			return (rc == -ENOMEM) ? ERR_PTR(-EAGAIN) :
+						 ERR_PTR(-EIO);
 		}
 		buf_desc->pages = virt_to_page(buf_desc->cpu_addr);
 		/* CDC header stored in buf. So, pretend it was smaller */

net/smc/smc_llc.c

@@ -233,8 +233,6 @@ static bool smc_llc_flow_start(struct smc_llc_flow *flow,
 	default:
 		flow->type = SMC_LLC_FLOW_NONE;
 	}
-	if (qentry == lgr->delayed_event)
-		lgr->delayed_event = NULL;
 	smc_llc_flow_qentry_set(flow, qentry);
 	spin_unlock_bh(&lgr->llc_flow_lock);
 	return true;
@@ -1603,13 +1601,12 @@ static void smc_llc_event_work(struct work_struct *work)
 	struct smc_llc_qentry *qentry;
 
 	if (!lgr->llc_flow_lcl.type && lgr->delayed_event) {
-		if (smc_link_usable(lgr->delayed_event->link)) {
-			smc_llc_event_handler(lgr->delayed_event);
-		} else {
-			qentry = lgr->delayed_event;
-			lgr->delayed_event = NULL;
+		qentry = lgr->delayed_event;
+		lgr->delayed_event = NULL;
+		if (smc_link_usable(qentry->link))
+			smc_llc_event_handler(qentry);
+		else
 			kfree(qentry);
-		}
 	}
 
 again: