The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-4.19.y git checkout FETCH_HEAD git cherry-pick -x 2fe8a236436fe40d8d26a1af8d150fc80f04ee1a # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2024021907-craziness-snuggle-7e2b@gregkh' --subject-prefix 'PATCH 4.19.y' HEAD^..

Possible dependencies:

2fe8a236436f ("s390/qeth: Fix potential loss of L3-IP@ in case of network issues")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 2fe8a236436fe40d8d26a1af8d150fc80f04ee1a Mon Sep 17 00:00:00 2001 From: Alexandra Winter wintera@linux.ibm.com Date: Tue, 6 Feb 2024 09:58:49 +0100 Subject: [PATCH] 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.

3caa4af834df ("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: 4a71df50047f ("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

diff --git a/drivers/s390/net/qeth_l3_main.c b/drivers/s390/net/qeth_l3_main.c index b92a32b4b114..04c64ce0a1ca 100644 --- a/drivers/s390/net/qeth_l3_main.c +++ b/drivers/s390/net/qeth_l3_main.c @@ -255,9 +255,10 @@ 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; } - 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); }