| Message ID | 20130820135033.GA2315@swordfish.minsk.epam.com |
|---|---|
| State | Rejected, archived |
| Delegated to: | David Miller |
| Headers | show |
> + if (need_locking) { > + /* genl_mutex could be already locked in genl_rcv_msg() */ > + rt = genl_family_find_byid(cb->nlh->nlmsg_type); > + need_locking = need_locking && rt->parallel_ops; > + } This is equivalent to reverting the patch because parallel_ops will be false for the genl family. :-) johannes
On (08/20/13 14:03), Berg, Johannes wrote: > > + if (need_locking) { > > + /* genl_mutex could be already locked in genl_rcv_msg() */ > > + rt = genl_family_find_byid(cb->nlh->nlmsg_type); > > + need_locking = need_locking && rt->parallel_ops; > > + } > > This is equivalent to reverting the patch because parallel_ops will be false for the genl family. :-) > sorry, didn't notice that there is already a thread on lkml regarding this issue. will follow that discussion. the reason was that I see an actual deadlock on my machine during certain network activities, but lockdep is silent. thanks, -ss > johannes > -- > > Intel GmbH > Dornacher Strasse 1 > 85622 Feldkirchen/Muenchen, Deutschland > Sitz der Gesellschaft: Feldkirchen bei Muenchen > Geschaeftsfuehrer: Christian Lamprechter, Hannes Schwaderer, Douglas Lusk > Registergericht: Muenchen HRB 47456 > Ust.-IdNr./VAT Registration No.: DE129385895 > Citibank Frankfurt a.M. (BLZ 502 109 00) 600119052 > -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c index f85f8a2..fca3659 100644 --- a/net/netlink/genetlink.c +++ b/net/netlink/genetlink.c @@ -791,6 +791,12 @@ static int ctrl_dumpfamily(struct sk_buff *skb, struct netlink_callback *cb) int fams_to_skip = cb->args[1]; bool need_locking = chains_to_skip || fams_to_skip; + if (need_locking) { + /* genl_mutex could be already locked in genl_rcv_msg() */ + rt = genl_family_find_byid(cb->nlh->nlmsg_type); + need_locking = need_locking && rt->parallel_ops; + } + if (need_locking) genl_lock();
Commmit 58ad436fcf49810aa006016107f494c9ac9013db Author: Johannes Berg <johannes.berg at intel.com> genetlink: fix family dump race added genl_lock() call to ctrl_dumpfamily(), which potentially can deadlock. Suppose the following case: genl_rcv_msg(): !family->parallel_ops -> genl_lock() genl_family_rcv_msg() netlink_dump_start() netlink_dump() ctrl_dumpfamily() --> genl_lock() Take in account possibility of genl_lock() in genl_rcv_msg() and do not acquire genl_mutex in ctrl_dumpfamily() for a family that supports parallel_ops. Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> --- net/netlink/genetlink.c | 6 ++++++ 1 file changed, 6 insertions(+) -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html