Commit 2fe8a236 authored Feb 06, 2024 by Alexandra Winter Committed by Paolo Abeni Feb 08, 2024

s390/qeth: Fix potential loss of L3-IP@ in case of network issues



Symptom:
In case of a bad cable connection (e.g. dirty optics) a fast sequence of
network DOWN-UP-DOWN-UP could happen. UP triggers recovery of the qeth
interface. In case of a second DOWN while recovery is still ongoing, it
can happen that the IP@ of a Layer3 qeth interface is lost and will not
be recovered by the second UP.

Problem:
When registration of IP addresses with Layer 3 qeth devices fails, (e.g.
because of bad address format) the respective IP address is deleted from
its hash-table in the driver. If registration fails because of a ENETDOWN
condition, the address should stay in the hashtable, so a subsequent
recovery can restore it.

3caa4af8 ("qeth: keep ip-address after LAN_OFFLINE failure")
fixes this for registration failures during normal operation, but not
during recovery.

Solution:
Keep L3-IP address in case of ENETDOWN in qeth_l3_recover_ip(). For
consistency with qeth_l3_add_ip() we also keep it in case of EADDRINUSE,
i.e. for some reason the card already/still has this address registered.

Fixes: 4a71df50 ("qeth: new qeth device driver")
Cc: stable@vger.kernel.org
Signed-off-by: Alexandra Winter <wintera@linux.ibm.com>
Link: https://lore.kernel.org/r/20240206085849.2902775-1-wintera@linux.ibm.com


Signed-off-by: Paolo Abeni <pabeni@redhat.com>

parent db010ff6

drivers/s390/net/qeth_l3_main.c

+6 −3

Original line number	Diff line number	Diff line
		@@ -255,10 +255,11 @@ static void qeth_l3_clear_ip_htable(struct qeth_card *card, int recover)
		if (!recover) {
		hash_del(&addr->hnode);
		kfree(addr);
		continue;
		}
		} else {
		/* prepare for recovery */
		addr->disp_flag = QETH_DISP_ADDR_ADD;
		}
		}

		mutex_unlock(&card->ip_lock);
		}
		@@ -278,9 +279,11 @@ static void qeth_l3_recover_ip(struct qeth_card *card)
		if (addr->disp_flag == QETH_DISP_ADDR_ADD) {
		rc = qeth_l3_register_addr_entry(card, addr);

		if (!rc) {
		if (!rc \|\| rc == -EADDRINUSE \|\| rc == -ENETDOWN) {
		/* keep it in the records */
		addr->disp_flag = QETH_DISP_ADDR_DO_NOTHING;
		} else {
		/* bad address */
		hash_del(&addr->hnode);
		kfree(addr);
		}