J. Bruce Fields b4f36f88b3 svcrpc: avoid memory-corruption on pool shutdown ... Socket callbacks use svc_xprt_enqueue() to add an xprt to a pool->sp_sockets list. In normal operation a server thread will later come along and take the xprt off that list. On shutdown, after all the threads have exited, we instead manually walk the sv_tempsocks and sv_permsocks lists to find all the xprt's and delete them. So the sp_sockets lists don't really matter any more. As a result, we've mostly just ignored them and hoped they would go away. Which has gotten us into trouble; witness for example ebc63e531c "svcrpc: fix list-corrupting race on nfsd shutdown", the result of Ben Greear noticing that a still-running svc_xprt_enqueue() could re-add an xprt to an sp_sockets list just before it was deleted. The fix was to remove it from the list at the end of svc_delete_xprt(). But that only made corruption less likely--I can see nothing that prevents a svc_xprt_enqueue() from adding another xprt to the list at the same moment that we're removing this xprt from the list. In fact, despite the earlier xpo_detach(), I don't even see what guarantees that svc_xprt_enqueue() couldn't still be running on this xprt. So, instead, note that svc_xprt_enqueue() essentially does: lock sp_lock if XPT_BUSY unset add to sp_sockets unlock sp_lock So, if we do: set XPT_BUSY on every xprt. Empty every sp_sockets list, under the sp_socks locks. Then we're left knowing that the sp_sockets lists are all empty and will stay that way, since any svc_xprt_enqueue() will check XPT_BUSY under the sp_lock and see it set. And *then* we can continue deleting the xprt's. (Thanks to Jeff Layton for being correctly suspicious of this code....) Cc: Ben Greear <greearb@candelatech.com> Cc: Jeff Layton <jlayton@redhat.com> Cc: stable@kernel.org Signed-off-by: J. Bruce Fields <bfields@redhat.com>		2011-12-06 16:18:58 -05:00
..
auth_gss	Merge branch 'nfs-for-3.2' of git://git.linux-nfs.org/projects/trondmy/linux-nfs	2011-10-25 15:44:06 +02:00
xprtrdma	net: Add export.h for EXPORT_SYMBOL/THIS_MODULE to non-modules	2011-10-31 19:30:30 -04:00
addr.c	net: Add export.h for EXPORT_SYMBOL/THIS_MODULE to non-modules	2011-10-31 19:30:30 -04:00
auth.c
auth_generic.c
auth_null.c
auth_unix.c	NFS/sunrpc: don't use a credential with extra groups.	2011-10-25 11:20:58 +02:00
backchannel_rqst.c	net: Add export.h for EXPORT_SYMBOL/THIS_MODULE to non-modules	2011-10-31 19:30:30 -04:00
bc_svc.c
cache.c
clnt.c	NFS: Get rid of nfs_restart_rpc()	2011-10-19 13:58:30 -07:00
Kconfig
Makefile
netns.h
rpc_pipe.c	Merge branch 'nfs-for-3.2' of git://git.linux-nfs.org/projects/trondmy/linux-nfs	2011-10-25 15:44:06 +02:00
rpcb_clnt.c	SUNRPC: remove rpcbind clients destruction on module cleanup	2011-10-25 13:20:50 +02:00
sched.c
socklib.c	net: Add export.h for EXPORT_SYMBOL/THIS_MODULE to non-modules	2011-10-31 19:30:30 -04:00
stats.c
sunrpc.h
sunrpc_syms.c	SUNRPC: remove rpcbind clients destruction on module cleanup	2011-10-25 13:20:50 +02:00
svc.c	svcrpc: avoid memory-corruption on pool shutdown	2011-12-06 16:18:58 -05:00
svc_xprt.c	svcrpc: avoid memory-corruption on pool shutdown	2011-12-06 16:18:58 -05:00
svcauth.c
svcauth_unix.c
svcsock.c	net: Fix files explicitly needing to include module.h	2011-10-31 19:30:28 -04:00
sysctl.c
timer.c
xdr.c
xprt.c	net: fix new sunrpc kernel-doc warning	2011-07-28 18:20:21 -07:00
xprtsock.c