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net: dcb: disable softirqs in dcbnl_flush_dev()

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Ido Schimmel points out that since commit 52cff74eef ("dcbnl : Disable
software interrupts before taking dcb_lock"), the DCB API can be called
by drivers from softirq context.

One such in-tree example is the chelsio cxgb4 driver:
dcb_rpl
-> cxgb4_dcb_handle_fw_update
   -> dcb_ieee_setapp

If the firmware for this driver happened to send an event which resulted
in a call to dcb_ieee_setapp() at the exact same time as another
DCB-enabled interface was unregistering on the same CPU, the softirq
would deadlock, because the interrupted process was already holding the
dcb_lock in dcbnl_flush_dev().

Fix this unlikely event by using spin_lock_bh() in dcbnl_flush_dev() as
in the rest of the dcbnl code.

Fixes: 91b0383fef ("net: dcb: flush lingering app table entries for unregistered devices")
Reported-by: Ido Schimmel <idosch@idosch.org>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://lore.kernel.org/r/20220302193939.1368823-1-vladimir.oltean@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Vladimir Oltean 2022-03-02 21:39:39 +02:00 committed by Jakub Kicinski
parent 8ccffe9ac3
commit 10b6bb62ae
1 changed files with 2 additions and 2 deletions
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4
net/dcb/dcbnl.c
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@ -2077,7 +2077,7 @@ static void dcbnl_flush_dev(struct net_device *dev)
{
struct dcb_app_type *itr, *tmp;
spin_lock(&dcb_lock);
spin_lock_bh(&dcb_lock);
list_for_each_entry_safe(itr, tmp, &dcb_app_list, list) {
if (itr->ifindex == dev->ifindex) {
@ -2086,7 +2086,7 @@ static void dcbnl_flush_dev(struct net_device *dev)
}
}
spin_unlock(&dcb_lock);
spin_unlock_bh(&dcb_lock);
}
static int dcbnl_netdevice_event(struct notifier_block *nb,