linux-toradex.git/fs/lockd/svc.c, branch v6.7

SUNRPC: change how svc threads are asked to exit.

2023-10-16T16:44:04+00:00

svc threads are currently stopped using kthread_stop().  This requires
identifying a specific thread.  However we don't care which thread
stops, just as long as one does.

So instead, set a flag in the svc_pool to say that a thread needs to
die, and have each thread check this flag instead of calling
kthread_should_stop().  The first thread to find and clear this flag
then moves towards exiting.

This removes an explicit dependency on sp_all_threads which will make a
future patch simpler.

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

lockd: hold a reference to nlmsvc_serv while stopping the thread.

2023-10-16T16:44:04+00:00

Both nfsd and nfsv4-callback take a temporary reference to the svc_serv
while calling svc_set_num_threads() to stop the last thread.  lockd does
not.

This extra reference prevents the scv_serv from being freed when the
last thread drops its reference count.  This is not currently needed
for lockd as the svc_serv is not accessed after the last thread is told
to exit.

However a future patch will require svc_exit_thread() to access the
svc_serv after the svc_put() so it will need the code that calls
svc_set_num_threads() to keep a reference and keep the svc_serv active.

So copy the pattern from nfsd and nfsv4-cb to lockd, and take a
reference around svc_set_num_threads(.., 0)

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

SUNRPC: Add enum svc_auth_status

2023-08-29T21:45:22+00:00

In addition to the benefits of using an enum rather than a set of
macros, we now have a named type that can improve static type
checking of function return values.

As part of this change, I removed a stale comment from svcauth.h;
the return values from current implementations of the
auth_ops::release method are all zero/negative errno, not the SVC_OK
enum values as the old comment suggested.

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

SUNRPC: remove timeout arg from svc_recv()

2023-08-29T21:45:22+00:00

Most svc threads have no interest in a timeout.
nfsd sets it to 1 hour, but this is a wart of no significance.

lockd uses the timeout so that it can call nlmsvc_retry_blocked().
It also sometimes calls svc_wake_up() to ensure this is called.

So change lockd to be consistent and always use svc_wake_up() to trigger
nlmsvc_retry_blocked() - using a timer instead of a timeout to
svc_recv().

And change svc_recv() to not take a timeout arg.

This makes the sp_threads_timedout counter always zero.

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

SUNRPC: change svc_recv() to return void.

2023-08-29T21:45:22+00:00

svc_recv() currently returns a 0 on success or one of two errors:
 - -EAGAIN means no message was successfully received
 - -EINTR means the thread has been told to stop

Previously nfsd would stop as the result of a signal as well as
following kthread_stop().  In that case the difference was useful: EINTR
means stop unconditionally.  EAGAIN means stop if kthread_should_stop(),
continue otherwise.

Now threads only exit when kthread_should_stop() so we don't need the
distinction.

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

SUNRPC: call svc_process() from svc_recv().

2023-08-29T21:45:22+00:00

All callers of svc_recv() go on to call svc_process() on success.
Simplify callers by having svc_recv() do that for them.

This loses one call to validate_process_creds() in nfsd.  That was
debugging code added 14 years ago.  I don't think we need to keep it.

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

lockd: remove SIGKILL handling

2023-08-29T21:45:22+00:00

lockd allows SIGKILL and responds by dropping all locks and restarting
the grace period.  This functionality has been present since 2.1.32 when
lockd was added to Linux.

This functionality is undocumented and most likely added as a useful
debug aid.  When there is a need to drop locks, the better approach is
to use /proc/fs/nfsd/unlock_*.

This patch removes SIGKILL handling as part of preparation for removing
all signal handling from sunrpc service threads.

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

lockd: drop inappropriate svc_get() from locked_get()

2023-06-12T16:16:34+00:00

The below-mentioned patch was intended to simplify refcounting on the
svc_serv used by locked.  The goal was to only ever have a single
reference from the single thread.  To that end we dropped a call to
lockd_start_svc() (except when creating thread) which would take a
reference, and dropped the svc_put(serv) that would drop that reference.

Unfortunately we didn't also remove the svc_get() from
lockd_create_svc() in the case where the svc_serv already existed.
So after the patch:
 - on the first call the svc_serv was allocated and the one reference
   was given to the thread, so there are no extra references
 - on subsequent calls svc_get() was called so there is now an extra
   reference.
This is clearly not consistent.

The inconsistency is also clear in the current code in lockd_get()
takes *two* references, one on nlmsvc_serv and one by incrementing
nlmsvc_users.   This clearly does not match lockd_put().

So: drop that svc_get() from lockd_get() (which used to be in
lockd_create_svc().

Reported-by: Ido Schimmel 
Closes: https://lore.kernel.org/linux-nfs/ZHsI%2FH16VX9kJQX1@shredder/T/#u
Fixes: b73a2972041b ("lockd: move lockd_start_svc() call into lockd_create_svc()")
Signed-off-by: NeilBrown 
Tested-by: Ido Schimmel 
Signed-off-by: Chuck Lever

Merge tag 'nfsd-6.4-1' of git://git.kernel.org/pub/scm/linux/kernel/git/cel/linux

2023-05-17T16:56:01+00:00

Pull nfsd fixes from Chuck Lever:

 - A collection of minor bug fixes

* tag 'nfsd-6.4-1' of git://git.kernel.org/pub/scm/linux/kernel/git/cel/linux:
  NFSD: Remove open coding of string copy
  SUNRPC: Fix trace_svc_register() call site
  SUNRPC: always free ctxt when freeing deferred request
  SUNRPC: double free xprt_ctxt while still in use
  SUNRPC: Fix error handling in svc_setup_socket()
  SUNRPC: Fix encoding of accepted but unsuccessful RPC replies
  lockd: define nlm_port_min,max with CONFIG_SYSCTL
  nfsd: define exports_proc_ops with CONFIG_PROC_FS
  SUNRPC: Avoid relying on crypto API to derive CBC-CTS output IV

lockd: define nlm_port_min,max with CONFIG_SYSCTL

2023-05-02T19:47:33+00:00

gcc with W=1 and ! CONFIG_SYSCTL
fs/lockd/svc.c:80:51: error: ‘nlm_port_max’ defined but not used [-Werror=unused-const-variable=]
   80 | static const int                nlm_port_min = 0, nlm_port_max = 65535;
      |                                                   ^~~~~~~~~~~~
fs/lockd/svc.c:80:33: error: ‘nlm_port_min’ defined but not used [-Werror=unused-const-variable=]
   80 | static const int                nlm_port_min = 0, nlm_port_max = 65535;
      |                                 ^~~~~~~~~~~~

The only use of these variables is when CONFIG_SYSCTL
is defined, so their definition should be likewise conditional.

Signed-off-by: Tom Rix 
Reviewed-by: Jeff Layton 
Signed-off-by: Chuck Lever