linux-stable.git/include/linux/sunrpc/svc.h, branch v6.15

sunrpc: remove all connection limit configuration

2025-01-06T14:37:36+00:00

Now that the connection limit only apply to unconfirmed connections,
there is no need to configure it.  So remove all the configuration and
fix the number of unconfirmed connections as always 64 - which is
now given a name: XPT_MAX_TMP_CONN

Signed-off-by: NeilBrown 
Reviewed-by: Jeff Layton 
Signed-off-by: Chuck Lever

nfsd: don't use sv_nrthreads in connection limiting calculations.

2025-01-06T14:37:36+00:00

The heuristic for limiting the number of incoming connections to nfsd
currently uses sv_nrthreads - allowing more connections if more threads
were configured.

A future patch will allow number of threads to grow dynamically so that
there will be no need to configure sv_nrthreads.  So we need a different
solution for limiting connections.

It isn't clear what problem is solved by limiting connections (as
mentioned in a code comment) but the most likely problem is a connection
storm - many connections that are not doing productive work.  These will
be closed after about 6 minutes already but it might help to slow down a
storm.

This patch adds a per-connection flag XPT_PEER_VALID which indicates
that the peer has presented a filehandle for which it has some sort of
access.  i.e the peer is known to be trusted in some way.  We now only
count connections which have NOT been determined to be valid.  There
should be relative few of these at any given time.

If the number of non-validated peer exceed a limit - currently 64 - we
close the oldest non-validated peer to avoid having too many of these
useless connections.

Note that this patch significantly changes the meaning of the various
configuration parameters for "max connections".  The next patch will
remove all of these.

Signed-off-by: NeilBrown 
Reviewed-by: Jeff Layton 
Signed-off-by: Chuck Lever

sunrpc/svc: use store_release_wake_up()

2025-01-06T14:37:34+00:00

svc_thread_init_status() contains an open-coded
store_release_wake_up().  It is cleaner to use that function directly
rather than needing to remember the barrier.

Signed-off-by: NeilBrown 
Reviewed-by: Jeff Layton 
Signed-off-by: Chuck Lever

SUNRPC: replace program list with program array

2024-09-23T19:03:30+00:00

A service created with svc_create_pooled() can be given a linked list of
programs and all of these will be served.

Using a linked list makes it cumbersome when there are several programs
that can be optionally selected with CONFIG settings.

After this patch is applied, API consumers must use only
svc_create_pooled() when creating an RPC service that listens for more
than one RPC program.

Signed-off-by: NeilBrown 
Signed-off-by: Mike Snitzer 
Acked-by: Chuck Lever 
Reviewed-by: Jeff Layton 
Signed-off-by: Anna Schumaker

sunrpc: allow svc threads to fail initialisation cleanly

2024-09-20T23:31:03+00:00

If an svc thread needs to perform some initialisation that might fail,
it has no good way to handle the failure.

Before the thread can exit it must call svc_exit_thread(), but that
requires the service mutex to be held.  The thread cannot simply take
the mutex as that could deadlock if there is a concurrent attempt to
shut down all threads (which is unlikely, but not impossible).

nfsd currently call svc_exit_thread() unprotected in the unlikely event
that unshare_fs_struct() fails.

We can clean this up by introducing svc_thread_init_status() by which an
svc thread can report whether initialisation has succeeded.  If it has,
it continues normally into the action loop.  If it has not,
svc_thread_init_status() immediately aborts the thread.
svc_start_kthread() waits for either of these to happen, and calls
svc_exit_thread() (under the mutex) if the thread aborted.

Signed-off-by: NeilBrown 
Reviewed-by: Jeff Layton 
Signed-off-by: Chuck Lever

sunrpc: change sp_nrthreads from atomic_t to unsigned int.

2024-09-20T23:31:03+00:00

sp_nrthreads is only ever accessed under the service mutex
  nlmsvc_mutex nfs_callback_mutex nfsd_mutex
so these is no need for it to be an atomic_t.

The fact that all code using it is single-threaded means that we can
simplify svc_pool_victim and remove the temporary elevation of
sp_nrthreads.

Signed-off-by: NeilBrown 
Signed-off-by: Chuck Lever

SUNRPC: make various functions static, or not exported.

2024-09-01T14:04:56+00:00

Various functions are only used within the sunrpc module, and several
are only use in the one file.  So clean up:

These are marked static, and any EXPORT is removed.
  svc_rcpb_setup()
  svc_rqst_alloc()
  svc_rqst_free()  - also moved before first use
  svc_rpcbind_set_version()
  svc_drop() - also moved to svc.c

These are now not EXPORTed, but are not static.
  svc_authenticate()
  svc_sock_update_bufs()

Signed-off-by: NeilBrown 
Signed-off-by: Chuck Lever

sunrpc: refactor pool_mode setting code

2024-07-08T18:10:05+00:00

Allow the pool_mode setting code to be called from internal callers
so we can call it from a new netlink op. Add a new svc_pool_map_get
function to return the current setting. Change the existing module
parameter handling to use the new interfaces under the hood.

Signed-off-by: Jeff Layton 
Signed-off-by: Chuck Lever

sunrpc: fix up the special handling of sv_nrpools == 1

2024-07-08T18:10:04+00:00

Only pooled services take a reference to the svc_pool_map. The sunrpc
code has always used the sv_nrpools value to detect whether the service
is pooled.

The problem there is that nfsd is a pooled service, but when it's
running in "global" pool_mode, it doesn't take a reference to the pool
map because it has a sv_nrpools value of 1. This means that we have
two separate codepaths for starting the server, depending on whether
it's pooled or not.

Fix this by adding a new flag to the svc_serv, that indicates whether
the serv is pooled. With this we can have the nfsd service
unconditionally take a reference, regardless of pool_mode.

Note that this is a behavior change for
/sys/module/sunrpc/parameters/pool_mode. Usually this file does not
allow you to change the pool-mode while there are nfsd threads running,
but if the pool-mode is "global" it's allowed. My assumption is that
this is a bug, since it probably should never have worked this way.

This patch changes the behavior such that you get back EBUSY even
when nfsd is running in global mode. I think this is more reasonable
behavior, and given that most people set this today using the module
parameter, it's doubtful anyone will notice.

Signed-off-by: Jeff Layton 
Signed-off-by: Chuck Lever

sunrpc: remove ->pg_stats from svc_program

2024-03-01T14:12:09+00:00

Now that this isn't used anywhere, remove it.

Signed-off-by: Josef Bacik 
Reviewed-by: Jeff Layton 
Signed-off-by: Chuck Lever