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s390/qeth: reduce rtnl locking for switchdev events
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call_switchdev_notifiers() doesn't require holding the RTNL lock since
commit ff5cf10 ("net: switchdev: Change notifier chain to be atomic").

We still need it for the "lost event" slow path, to avoid racing against
a concurrent .ndo_bridge_setlink().

Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Reviewed-by: Alexandra Winter <wintera@linux.ibm.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Julian Wiedmann authored and Jakub Kicinski committed Nov 19, 2020
1 parent bd4bdeb commit 09840f7
Showing 1 changed file with 15 additions and 18 deletions.
33 changes: 15 additions & 18 deletions drivers/s390/net/qeth_l2_main.c
Original file line number Diff line number Diff line change
Expand Up @@ -737,8 +737,6 @@ static void qeth_l2_dev2br_an_set_cb(void *priv,
*
* On enable, emits a series of address notifications for all
* currently registered hosts.
*
* Must be called under rtnl_lock
*/
static int qeth_l2_dev2br_an_set(struct qeth_card *card, bool enable)
{
Expand Down Expand Up @@ -1289,16 +1287,19 @@ static void qeth_l2_dev2br_worker(struct work_struct *work)
if (READ_ONCE(card->info.pnso_mode) == QETH_PNSO_NONE)
goto free;

/* Potential re-config in progress, try again later: */
if (!rtnl_trylock()) {
queue_delayed_work(card->event_wq, dwork,
msecs_to_jiffies(100));
return;
}
if (!netif_device_present(card->dev))
goto out_unlock;

if (data->ac_event.lost_event_mask) {
/* Potential re-config in progress, try again later: */
if (!rtnl_trylock()) {
queue_delayed_work(card->event_wq, dwork,
msecs_to_jiffies(100));
return;
}

if (!netif_device_present(card->dev)) {
rtnl_unlock();
goto free;
}

QETH_DBF_MESSAGE(3,
"Address change notification overflow on device %x\n",
CARD_DEVID(card));
Expand Down Expand Up @@ -1328,6 +1329,8 @@ static void qeth_l2_dev2br_worker(struct work_struct *work)
"Address Notification resynced on device %x\n",
CARD_DEVID(card));
}

rtnl_unlock();
} else {
for (i = 0; i < data->ac_event.num_entries; i++) {
struct qeth_ipacmd_addr_change_entry *entry =
Expand All @@ -1339,9 +1342,6 @@ static void qeth_l2_dev2br_worker(struct work_struct *work)
}
}

out_unlock:
rtnl_unlock();

free:
kfree(data);
}
Expand Down Expand Up @@ -2310,11 +2310,8 @@ static void qeth_l2_set_offline(struct qeth_card *card)
card->state = CARD_STATE_DOWN;

qeth_l2_set_pnso_mode(card, QETH_PNSO_NONE);
if (priv->brport_features & BR_LEARNING_SYNC) {
rtnl_lock();
if (priv->brport_features & BR_LEARNING_SYNC)
qeth_l2_dev2br_fdb_flush(card);
rtnl_unlock();
}
}

/* Returns zero if the command is successfully "consumed" */
Expand Down

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