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s390/qeth: fix dangling IO buffers after halt/clear

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The cio layer's intparm logic does not align itself well with how qeth
manages cmd IOs. When an active IO gets terminated via halt/clear, the
corresponding IRQ's intparm does not reflect the cmd buffer but rather
the intparm that was passed to ccw_device_halt() / ccw_device_clear().
This behaviour was recently clarified in
commit b91d9e67e5 ("s390/cio: fix intparm documentation").

As a result, qeth_irq() currently doesn't cancel a cmd that was
terminated via halt/clear. This primarily causes us to leak
card->read_cmd after the qeth device is removed, since our IO path still
holds a refcount for this cmd.

For qeth this means that we need to keep track of which IO is pending on
a device ('active_cmd'), and use this as the intparm when calling
halt/clear. Otherwise qeth_irq() can't match the subsequent IRQ to its
cmd buffer.
Since we now keep track of the _expected_ intparm, we can also detect
any mismatch; this would constitute a bug somewhere in the lower layers.
In this case cancel the active cmd - we effectively "lost" the IRQ and
should not expect any further notification for this IO.

Fixes: 405548959c ("s390/qeth: add support for dynamically allocated cmds")
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Julian Wiedmann
2019-12-05 14:33:04 +01:00
committed by David S. Miller
parent f677fcb9ae
commit f9e50b02a9
5 changed files with 67 additions and 46 deletions
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12
drivers/s390/net/qeth_l2_main.c
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@@ -845,9 +845,9 @@ static int qeth_l2_set_online(struct ccwgroup_device *gdev)
out_remove:
qeth_l2_stop_card(card);
ccw_device_set_offline(CARD_DDEV(card));
ccw_device_set_offline(CARD_WDEV(card));
ccw_device_set_offline(CARD_RDEV(card));
qeth_stop_channel(&card->data);
qeth_stop_channel(&card->write);
qeth_stop_channel(&card->read);
qdio_free(CARD_DDEV(card));
mutex_unlock(&card->conf_mutex);
@@ -878,9 +878,9 @@ static int __qeth_l2_set_offline(struct ccwgroup_device *cgdev,
rtnl_unlock();
qeth_l2_stop_card(card);
rc = ccw_device_set_offline(CARD_DDEV(card));
rc2 = ccw_device_set_offline(CARD_WDEV(card));
rc3 = ccw_device_set_offline(CARD_RDEV(card));
rc = qeth_stop_channel(&card->data);
rc2 = qeth_stop_channel(&card->write);
rc3 = qeth_stop_channel(&card->read);
if (!rc)
rc = (rc2) ? rc2 : rc3;
if (rc)