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Date: Wed, 2 Mar 2022 21:39:39 +0200 From: Vladimir Oltean <vladimir.oltean@....com> To: netdev@...r.kernel.org Cc: "David S. Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, John Fastabend <john.fastabend@...il.com>, Petr Machata <petrm@...dia.com>, Ido Schimmel <idosch@...dia.com>, Ido Schimmel <idosch@...sch.org> Subject: [PATCH net] net: dcb: disable softirqs in dcbnl_flush_dev() Ido Schimmel points out that since commit 52cff74eef5d ("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: 91b0383fef06 ("net: dcb: flush lingering app table entries for unregistered devices") Reported-by: Ido Schimmel <idosch@...sch.org> Signed-off-by: Vladimir Oltean <vladimir.oltean@....com> --- net/dcb/dcbnl.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/dcb/dcbnl.c b/net/dcb/dcbnl.c index 36c91273daac..dc4fb699b56c 100644 --- a/net/dcb/dcbnl.c +++ b/net/dcb/dcbnl.c @@ -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, -- 2.25.1
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