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27f0ad7169
napi_disable() is subject to an hangup, when the threaded
mode is enabled and the napi is under heavy traffic.
If the relevant napi has been scheduled and the napi_disable()
kicks in before the next napi_threaded_wait() completes - so
that the latter quits due to the napi_disable_pending() condition,
the existing code leaves the NAPI_STATE_SCHED bit set and the
napi_disable() loop waiting for such bit will hang.
This patch addresses the issue by dropping the NAPI_STATE_DISABLE
bit test in napi_thread_wait(). The later napi_threaded_poll()
iteration will take care of clearing the NAPI_STATE_SCHED.
This also addresses a related problem reported by Jakub:
before this patch a napi_disable()/napi_enable() pair killed
the napi thread, effectively disabling the threaded mode.
On the patched kernel napi_disable() simply stops scheduling
the relevant thread.
v1 -> v2:
- let the main napi_thread_poll() loop clear the SCHED bit
Reported-by: Jakub Kicinski <kuba@kernel.org>
Fixes:
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.. | ||
bpf_sk_storage.c | ||
datagram.c | ||
datagram.h | ||
dev.c | ||
dev_addr_lists.c | ||
dev_ioctl.c | ||
devlink.c | ||
drop_monitor.c | ||
dst.c | ||
dst_cache.c | ||
failover.c | ||
fib_notifier.c | ||
fib_rules.c | ||
filter.c | ||
flow_dissector.c | ||
flow_offload.c | ||
gen_estimator.c | ||
gen_stats.c | ||
gro_cells.c | ||
hwbm.c | ||
link_watch.c | ||
lwt_bpf.c | ||
lwtunnel.c | ||
Makefile | ||
neighbour.c | ||
net-procfs.c | ||
net-sysfs.c | ||
net-sysfs.h | ||
net-traces.c | ||
net_namespace.c | ||
netclassid_cgroup.c | ||
netevent.c | ||
netpoll.c | ||
netprio_cgroup.c | ||
page_pool.c | ||
pktgen.c | ||
ptp_classifier.c | ||
request_sock.c | ||
rtnetlink.c | ||
scm.c | ||
secure_seq.c | ||
skbuff.c | ||
skmsg.c | ||
sock.c | ||
sock_diag.c | ||
sock_map.c | ||
sock_reuseport.c | ||
stream.c | ||
sysctl_net_core.c | ||
timestamping.c | ||
tso.c | ||
utils.c | ||
xdp.c |