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net: hdlc_ppp: Fix issues when mod_timer is called while timer is running
ppp_cp_event is called directly or indirectly by ppp_rx with "ppp->lock"
held. It may call mod_timer to add a new timer. However, at the same time
ppp_timer may be already running and waiting for "ppp->lock". In this
case, there's no need for ppp_timer to continue running and it can just
exit.
If we let ppp_timer continue running, it may call add_timer. This causes
kernel panic because add_timer can't be called with a timer pending.
This patch fixes this problem.
Fixes: e022c2f07a
("WAN: new synchronous PPP implementation for generic HDLC.")
Cc: Krzysztof Halasa <khc@pm.waw.pl>
Signed-off-by: Xie He <xie.he.0141@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
parent
9b22fece78
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@ -569,6 +569,13 @@ static void ppp_timer(struct timer_list *t)
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unsigned long flags;
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spin_lock_irqsave(&ppp->lock, flags);
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/* mod_timer could be called after we entered this function but
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* before we got the lock.
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*/
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if (timer_pending(&proto->timer)) {
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spin_unlock_irqrestore(&ppp->lock, flags);
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return;
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}
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switch (proto->state) {
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case STOPPING:
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case REQ_SENT:
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