forked from luck/tmp_suning_uos_patched
95503d295a
In the rpc server, When something happens that might be reason to wake up a thread to do something, what we do is - modify xpt_flags, sk_sock->flags, xpt_reserved, or xpt_nr_rqsts to indicate the new situation - call svc_xprt_enqueue() to decide whether to wake up a thread. svc_xprt_enqueue may require multiple conditions to be true before queueing up a thread to handle the xprt. In the SMP case, one of the other CPU's may have set another required condition, and in that case, although both CPUs run svc_xprt_enqueue(), it's possible that neither call sees the writes done by the other CPU in time, and neither one recognizes that all the required conditions have been set. A socket could therefore be ignored indefinitely. Add memory barries to ensure that any svc_xprt_enqueue() call will always see the conditions changed by other CPUs before deciding to ignore a socket. I've never seen this race reported. In the unlikely event it happens, another event will usually come along and the problem will fix itself. So I don't think this is worth backporting to stable. Chuck tried this patch and said "I don't see any performance regressions, but my server has only a single last-level CPU cache." Tested-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com> |
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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 | ||
| hsr | ||
| ieee802154 | ||
| ife | ||
| ipv4 | ||
| ipv6 | ||
| iucv | ||
| kcm | ||
| key | ||
| l2tp | ||
| l3mdev | ||
| lapb | ||
| llc | ||
| mac80211 | ||
| mac802154 | ||
| mpls | ||
| 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 | ||
| wimax | ||
| wireless | ||
| x25 | ||
| xdp | ||
| xfrm | ||
| compat.c | ||
| Kconfig | ||
| Makefile | ||
| socket.c | ||
| sysctl_net.c | ||