linux-toradex.git/net/sunrpc/svc.c, branch v3.0.75

NFSv4.1: Fix a request leak on the back channel

2012-06-22T18:34:13+00:00

commit b3b02ae5865c2dcd506322e0fc6def59a042e72f upstream.

If the call to svc_process_common() fails, then the request
needs to be freed before we can exit bc_svc_process.

Signed-off-by: Trond Myklebust 
Signed-off-by: Greg Kroah-Hartman

svcrpc: avoid memory-corruption on pool shutdown

2012-01-26T01:24:48+00:00

commit b4f36f88b3ee7cf26bf0be84e6c7fc15f84dcb71 upstream.

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 ebc63e531cc6
"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 
Cc: Jeff Layton 
Signed-off-by: J. Bruce Fields 
Signed-off-by: Greg Kroah-Hartman

svcrpc: destroy server sockets all at once

2012-01-26T01:24:48+00:00

commit 2fefb8a09e7ed251ae8996e0c69066e74c5aa560 upstream.

There's no reason I can see that we need to call sv_shutdown between
closing the two lists of sockets.

Signed-off-by: J. Bruce Fields 
Signed-off-by: Greg Kroah-Hartman

svcrpc: fix double-free on shutdown of nfsd after changing pool mode

2012-01-26T01:24:47+00:00

commit 61c8504c428edcebf23b97775a129c5b393a302b upstream.

The pool_to and to_pool fields of the global svc_pool_map are freed on
shutdown, but are initialized in nfsd startup only in the
SVC_POOL_PERCPU and SVC_POOL_PERNODE cases.

They *are* initialized to zero on kernel startup.  So as long as you use
only SVC_POOL_GLOBAL (the default), this will never be a problem.

You're also OK if you only ever use SVC_POOL_PERCPU or SVC_POOL_PERNODE.

However, the following sequence events leads to a double-free:

	1. set SVC_POOL_PERCPU or SVC_POOL_PERNODE
	2. start nfsd: both fields are initialized.
	3. shutdown nfsd: both fields are freed.
	4. set SVC_POOL_GLOBAL
	5. start nfsd: the fields are left untouched.
	6. shutdown nfsd: now we try to free them again.

Step 4 is actually unnecessary, since (for some bizarre reason), nfsd
automatically resets the pool mode to SVC_POOL_GLOBAL on shutdown.

Signed-off-by: J. Bruce Fields 
Signed-off-by: Greg Kroah-Hartman

SUNRPC: Use AF_LOCAL for rpcbind upcalls

2011-05-27T21:42:47+00:00

As libtirpc does in user space, have our registration API try using an
AF_LOCAL transport first when registering and unregistering.

This means we don't chew up privileged ports, and our registration is
bound to an "owner" (the effective uid of the process on the sending
end of the transport).  Only that "owner" may unregister the service.

The kernel could probe rpcbind via an rpcbind query to determine
whether rpcbind has an AF_LOCAL service. For simplicity, we use the
same technique that libtirpc uses: simply fail over to network
loopback if creating an AF_LOCAL transport to the well-known rpcbind
service socket fails.

This means we open-code the pathname of the rpcbind socket in the
kernel.  For now we have to do that anyway because the kernel's
RPC over AF_LOCAL implementation does not support autobind.  That may
be undesirable in the long term.

Signed-off-by: Chuck Lever 
Signed-off-by: Trond Myklebust

Merge branch 'for-2.6.38' of git://linux-nfs.org/~bfields/linux

2011-01-14T21:17:26+00:00

* 'for-2.6.38' of git://linux-nfs.org/~bfields/linux: (62 commits)
  nfsd4: fix callback restarting
  nfsd: break lease on unlink, link, and rename
  nfsd4: break lease on nfsd setattr
  nfsd: don't support msnfs export option
  nfsd4: initialize cb_per_client
  nfsd4: allow restarting callbacks
  nfsd4: simplify nfsd4_cb_prepare
  nfsd4: give out delegations more quickly in 4.1 case
  nfsd4: add helper function to run callbacks
  nfsd4: make sure sequence flags are set after destroy_session
  nfsd4: re-probe callback on connection loss
  nfsd4: set sequence flag when backchannel is down
  nfsd4: keep finer-grained callback status
  rpc: allow xprt_class->setup to return a preexisting xprt
  rpc: keep backchannel xprt as long as server connection
  rpc: move sk_bc_xprt to svc_xprt
  nfsd4: allow backchannel recovery
  nfsd4: support BIND_CONN_TO_SESSION
  nfsd4: modify session list under cl_lock
  Documentation: fl_mylease no longer exists
  ...

Fix up conflicts in fs/nfsd/vfs.c with the vfs-scale work.  The
vfs-scale work touched some msnfs cases, and this merge removes support
for that entirely, so the conflict was trivial to resolve.

NFS rename client back channel transport field

2011-01-06T19:46:25+00:00

Differentiate from server backchannel

Signed-off-by: Andy Adamson 
Acked-by: Bruce Fields 
Signed-off-by: Trond Myklebust

SUNRPC new transport for the NFSv4.1 shared back channel

2011-01-06T19:46:23+00:00

Move the current sock create and destroy routines into the new transport ops.
Back channel socket will be destroyed by the svc_closs_all call in svc_destroy.

Added check: only TCP supported on shared back channel.

Signed-off-by: Andy Adamson 
Acked-by: Bruce Fields 
Signed-off-by: Trond Myklebust

SUNRPC move svc_drop to caller of svc_process_common

2011-01-06T19:46:23+00:00

The NFSv4.1 shared back channel does not need to call svc_drop because the
callback service never outlives the single connection it services, and it
reuses it's buffers and keeps the trasport.

Signed-off-by: Andy Adamson 
Acked-by: Bruce Fields 
Signed-off-by: Trond Myklebust

svcrpc: simpler request dropping

2011-01-04T21:49:22+00:00

Currently we use -EAGAIN returns to determine when to drop a deferred
request.  On its own, that is error-prone, as it makes us treat -EAGAIN
returns from other functions specially to prevent inadvertent dropping.

So, use a flag on the request instead.

Returning an error on request deferral is still required, to prevent
further processing, but we no longer need worry that an error return on
its own could result in a drop.

Signed-off-by: J. Bruce Fields