mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson
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85670cc1fa
The move of qdisc destruction to a rcu callback broke locking in the entire qdisc layer by invalidating previously valid assumptions about the context in which changes to the qdisc tree occur. The two assumptions were: - since changes only happen in process context, read_lock doesn't need bottem half protection. Now invalid since destruction of inner qdiscs, classifiers, actions and estimators happens in the RCU callback unless they're manually deleted, resulting in dead-locks when read_lock in process context is interrupted by write_lock_bh in bottem half context. - since changes only happen under the RTNL, no additional locking is necessary for data not used during packet processing (f.e. u32_list). Again, since destruction now happens in the RCU callback, this assumption is not valid anymore, causing races while using this data, which can result in corruption or use-after-free. Instead of "fixing" this by disabling bottem halfs everywhere and adding new locks/refcounting, this patch makes these assumptions valid again by moving destruction back to process context. Since only the dev->qdisc pointer is protected by RCU, but ->enqueue and the qdisc tree are still protected by dev->qdisc_lock, destruction of the tree can be performed immediately and only the final free needs to happen in the rcu callback to make sure dev_queue_xmit doesn't access already freed memory. Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: David S. Miller <davem@davemloft.net> |
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| .. | ||
| act_api.c | ||
| act_gact.c | ||
| act_ipt.c | ||
| act_mirred.c | ||
| act_pedit.c | ||
| act_police.c | ||
| act_simple.c | ||
| cls_api.c | ||
| cls_basic.c | ||
| cls_fw.c | ||
| cls_route.c | ||
| cls_rsvp6.c | ||
| cls_rsvp.c | ||
| cls_rsvp.h | ||
| cls_tcindex.c | ||
| cls_u32.c | ||
| em_cmp.c | ||
| em_meta.c | ||
| em_nbyte.c | ||
| em_text.c | ||
| em_u32.c | ||
| ematch.c | ||
| estimator.c | ||
| Kconfig | ||
| Makefile | ||
| sch_api.c | ||
| sch_atm.c | ||
| sch_blackhole.c | ||
| sch_cbq.c | ||
| sch_dsmark.c | ||
| sch_fifo.c | ||
| sch_generic.c | ||
| sch_gred.c | ||
| sch_hfsc.c | ||
| sch_htb.c | ||
| sch_ingress.c | ||
| sch_netem.c | ||
| sch_prio.c | ||
| sch_red.c | ||
| sch_sfq.c | ||
| sch_tbf.c | ||
| sch_teql.c | ||