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r8152: Re-order napi_disable in rtl8152_close 

Both rtl_work_func_t() and rtl8152_close() call napi_disable().
Since the two calls aren't protected by a lock, if the close
function starts executing before the work function, we can get into a
situation where the napi_disable() function is called twice in
succession (first by rtl8152_close(), then by set_carrier()).

In such a situation, the second call would loop indefinitely, since
rtl8152_close() doesn't call napi_enable() to clear the NAPI_STATE_SCHED
bit.

The rtl8152_close() function in turn issues a
cancel_delayed_work_sync(), and so it would wait indefinitely for the
rtl_work_func_t() to complete. Since rtl8152_close() is called by a
process holding rtnl_lock() which is requested by other processes, this
eventually leads to a system deadlock and crash.

Re-order the napi_disable() call to occur after the work function
disabling and urb cancellation calls are issued.

Change-Id: I6ef0b703fc214998a037a68f722f784e1d07815e
Reported-by: http://crbug.com/1017928
Signed-off-by: Prashant Malani <pmalani@chromium.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Prashant Malani 2019-11-20 11:40:21 -08:00 committed by David S. Miller
parent b172845a40
commit 8481141246
1 changed files with 1 additions and 1 deletions
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2
drivers/net/usb/r8152.c
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@ -4283,10 +4283,10 @@ static int rtl8152_close(struct net_device *netdev)
unregister_pm_notifier(&tp->pm_notifier);
#endif
tasklet_disable(&tp->tx_tl);
napi_disable(&tp->napi);
clear_bit(WORK_ENABLE, &tp->flags);
usb_kill_urb(tp->intr_urb);
cancel_delayed_work_sync(&tp->schedule);
napi_disable(&tp->napi);
netif_stop_queue(netdev);
res = usb_autopm_get_interface(tp->intf);