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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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| .. | ||
| 6lowpan | ||
| 9p | ||
| 802 | ||
| 8021q | ||
| appletalk | ||
| atm | ||
| ax25 | ||
| batman-adv | ||
| bluetooth | ||
| bpf | ||
| bpfilter | ||
| bridge | ||
| caif | ||
| can | ||
| ceph | ||
| core | ||
| dcb | ||
| dccp | ||
| decnet | ||
| dns_resolver | ||
| dsa | ||
| ethernet | ||
| ethtool | ||
| hsr | ||
| ieee802154 | ||
| ife | ||
| ipv4 | ||
| ipv6 | ||
| iucv | ||
| kcm | ||
| key | ||
| l2tp | ||
| l3mdev | ||
| lapb | ||
| llc | ||
| mac80211 | ||
| mac802154 | ||
| mpls | ||
| mptcp | ||
| ncsi | ||
| netfilter | ||
| netlabel | ||
| netlink | ||
| netrom | ||
| nfc | ||
| nsh | ||
| openvswitch | ||
| packet | ||
| phonet | ||
| psample | ||
| qrtr | ||
| rds | ||
| rfkill | ||
| rose | ||
| rxrpc | ||
| sched | ||
| sctp | ||
| smc | ||
| strparser | ||
| sunrpc | ||
| switchdev | ||
| tipc | ||
| tls | ||
| unix | ||
| vmw_vsock | ||
| wireless | ||
| x25 | ||
| xdp | ||
| xfrm | ||
| compat.c | ||
| devres.c | ||
| Kconfig | ||
| Makefile | ||
| socket.c | ||
| sysctl_net.c | ||