Comment 3 for bug 1984103

Revision history for this message
bugproxy (bugproxy) wrote : Comment bridged from LTC Bugzilla

------- Comment From <email address hidden> 2022-08-10 04:10 EDT-------
clarification from development on the overall situation:

Symptoms:
A) Since
02d5cb5bb20b ("qeth: Accurate ethtool output")
query_card_info is called for each qeth_get_link_ksettings
Frequent calls to ethtool?s get_link_ksetting can put pressure on the zVM VSwitch
that lead to timeouts in the qeth driver that responds with recovering the affected interface.

B) Since
e6e771b3d897 ("s390/qeth: detach netdevice while card is offline")
there is a window condition that query_card_info can interfere with recovery and
lead to failing recovery.

7a07a29e4f67 ("s390/qeth: cache link_info for ethtool") solves both problems.

Backport considerations:
A) 02d5cb5bb20b ("qeth: Accurate ethtool output")
went into kernel v3.14 and was backported to RHEL7.9

B) e6e771b3d897 ("s390/qeth: detach netdevice while card is offline")
went into kernel v5.1 and was backported to RHEL8.2