| Message ID | 9867ac04591f1d30b2471cea1b091134f812fd60.1649310812.git.duoming@zju.edu.cn |
|---|---|
| State | New |
| Headers | show |
| Series | Fix deadlocks caused by del_timer_sync() | expand |
diff --git a/arch/xtensa/platforms/iss/network.c b/arch/xtensa/platforms/iss/network.c index be3aaaad8be..48340f17e39 100644 --- a/arch/xtensa/platforms/iss/network.c +++ b/arch/xtensa/platforms/iss/network.c @@ -403,7 +403,9 @@ static int iss_net_close(struct net_device *dev) list_del(&opened); spin_unlock(&opened_lock); + spin_unlock_bh(&lp->lock); del_timer_sync(&lp->timer); + spin_lock_bh(&lp->lock); lp->tp.close(lp);
There is a deadlock in iss_net_close(), which is shown below: (Thread 1) | (Thread 2) | iss_net_open() iss_net_close() | mod_timer() spin_lock_bh() //(1) | (wait a time) ... | iss_net_timer() del_timer_sync() | spin_lock() //(2) (wait timer to stop) | ... We hold lp->lock in position (1) of thread 1 and use del_timer_sync() to wait timer to stop, but timer handler also need lp->lock in position (2) of thread 2. As a result, iss_net_close() will block forever. This patch extracts del_timer_sync() from the protection of spin_lock_bh(), which could let timer handler to obtain the needed lock. Signed-off-by: Duoming Zhou <duoming@zju.edu.cn> --- arch/xtensa/platforms/iss/network.c | 2 ++ 1 file changed, 2 insertions(+)