Ahmed S. Darwish 11d6011c2c net: core: device_rename: Use rwsem instead of a seqcount ... Sequence counters write paths are critical sections that must never be preempted, and blocking, even for CONFIG_PREEMPTION=n, is not allowed. Commit 5dbe7c178d ("net: fix kernel deadlock with interface rename and netdev name retrieval.") handled a deadlock, observed with CONFIG_PREEMPTION=n, where the devnet_rename seqcount read side was infinitely spinning: it got scheduled after the seqcount write side blocked inside its own critical section. To fix that deadlock, among other issues, the commit added a cond_resched() inside the read side section. While this will get the non-preemptible kernel eventually unstuck, the seqcount reader is fully exhausting its slice just spinning -- until TIF_NEED_RESCHED is set. The fix is also still broken: if the seqcount reader belongs to a real-time scheduling policy, it can spin forever and the kernel will livelock. Disabling preemption over the seqcount write side critical section will not work: inside it are a number of GFP_KERNEL allocations and mutex locking through the drivers/base/ :: device_rename() call chain. >From all the above, replace the seqcount with a rwsem. Fixes: 5dbe7c178d (net: fix kernel deadlock with interface rename and netdev name retrieval.) Fixes: 30e6c9fa93 (net: devnet_rename_seq should be a seqcount) Fixes: c91f6df2db (sockopt: Change getsockopt() of SO_BINDTODEVICE to return an interface name) Cc: <stable@vger.kernel.org> Reported-by: kbuild test robot <lkp@intel.com> [ v1 missing up_read() on error exit ] Reported-by: Dan Carpenter <dan.carpenter@oracle.com> [ v1 missing up_read() on error exit ] Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de> Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: David S. Miller <davem@davemloft.net>		2020-06-04 15:50:42 -07:00
..
bpf_sk_storage.c	bpf: Implement CAP_BPF	2020-05-15 17:29:41 +02:00
datagram.c
datagram.h
dev_addr_lists.c
dev_ioctl.c
dev.c	net: core: device_rename: Use rwsem instead of a seqcount	2020-06-04 15:50:42 -07:00
devlink.c	devlink: Add ACL control packet traps	2020-06-01 11:49:23 -07:00
drop_monitor.c
dst_cache.c
dst.c	net/dst: use a smaller percpu_counter batch for dst entries accounting	2020-05-08 21:33:33 -07:00
failover.c
fib_notifier.c
fib_rules.c
filter.c	seg6: fix seg6_validate_srh() to avoid slab-out-of-bounds	2020-06-04 15:39:32 -07:00
flow_dissector.c	flow_dissector: Move out netns_bpf prog callbacks	2020-06-01 15:21:02 -07:00
flow_offload.c	net: remove indirect block netdev event registration	2020-06-01 11:41:50 -07:00
gen_estimator.c
gen_stats.c
gro_cells.c
hwbm.c
link_watch.c
lwt_bpf.c
lwtunnel.c
Makefile
neighbour.c	Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net	2020-05-31 17:48:46 -07:00
net_namespace.c	nsproxy: add struct nsset	2020-05-09 13:57:12 +02:00
net-procfs.c
net-sysfs.c	net: core: recursively find netdev by device node	2020-05-15 10:18:49 -07:00
net-sysfs.h
net-traces.c
netclassid_cgroup.c
netevent.c
netpoll.c
netprio_cgroup.c	netprio_cgroup: Fix unlimited memory leak of v2 cgroups	2020-05-09 20:59:21 -07:00
page_pool.c
pktgen.c
ptp_classifier.c
request_sock.c
rtnetlink.c
scm.c	net: ignore sock_from_file errors in __scm_install_fd	2020-05-13 12:30:54 -07:00
secure_seq.c
skbuff.c	net: unexport skb_gro_receive()	2020-05-19 19:55:36 -07:00
skmsg.c	bpf: Fix running sk_skb program types with ktls	2020-06-01 14:48:32 -07:00
sock_diag.c
sock_map.c
sock_reuseport.c
sock.c	net: Make locking in sock_bindtoindex optional	2020-06-01 14:57:14 -07:00
stream.c
sysctl_net_core.c	netns: enable to inherit devconf from current netns	2020-05-16 13:46:37 -07:00
timestamping.c
tso.c
utils.c
xdp.c	xdp: Simplify xdp_return_{frame, frame_rx_napi, buff}	2020-05-21 17:31:27 -07:00