nfsd: don't allow nfsd threads to be signalled.

commit 3903902401451b1cd9d797a8c79769eb26ac7fe5 upstream.

The original implementation of nfsd used signals to stop threads during
shutdown.
In Linux 2.3.46pre5 nfsd gained the ability to shutdown threads
internally it if was asked to run "0" threads.  After this user-space
transitioned to using "rpc.nfsd 0" to stop nfsd and sending signals to
threads was no longer an important part of the API.

In commit 3ebdbe5203a8 ("SUNRPC: discard svo_setup and rename
svc_set_num_threads_sync()") (v5.17-rc1~75^2~41) we finally removed the
use of signals for stopping threads, using kthread_stop() instead.

This patch makes the "obvious" next step and removes the ability to
signal nfsd threads - or any svc threads.  nfsd stops allowing signals
and we don't check for their delivery any more.

This will allow for some simplification in later patches.

A change worth noting is in nfsd4_ssc_setup_dul().  There was previously
a signal_pending() check which would only succeed when the thread was
being shut down.  It should really have tested kthread_should_stop() as
well.  Now it just does the latter, not the former.

Signed-off-by: NeilBrown <neilb@suse.de>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/nfs/callback.c b/fs/nfs/callback.c
index 456af7d230cf180ec0b7d22dc1d498726ce70a7a..46a0a2d6962e1c81b8dbb6663748befb5bb93f3a 100644 (file)
--- a/fs/nfs/callback.c
+++ b/fs/nfs/callback.c
@@ -80,9 +80,6 @@ nfs4_callback_svc(void *vrqstp)
        set_freezable();
 
        while (!kthread_freezable_should_stop(NULL)) {
-
-               if (signal_pending(current))
-                       flush_signals(current);
                /*
                 * Listen for a request on the socket
                 */
@@ -112,11 +109,7 @@ nfs41_callback_svc(void *vrqstp)
        set_freezable();
 
        while (!kthread_freezable_should_stop(NULL)) {
-
-               if (signal_pending(current))
-                       flush_signals(current);
-
-               prepare_to_wait(&serv->sv_cb_waitq, &wq, TASK_INTERRUPTIBLE);
+               prepare_to_wait(&serv->sv_cb_waitq, &wq, TASK_IDLE);
                spin_lock_bh(&serv->sv_cb_lock);
                if (!list_empty(&serv->sv_cb_list)) {
                        req = list_first_entry(&serv->sv_cb_list,

diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index c14f5ac1484c9a2d94fd16b75aebc9e5cf39dbdc..6779291efca9ede8fda556123e8900211f76e1c0 100644 (file)
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -1317,12 +1317,11 @@ try_again:
                /* found a match */
                if (ni->nsui_busy) {
                        /*  wait - and try again */
-                       prepare_to_wait(&nn->nfsd_ssc_waitq, &wait,
-                               TASK_INTERRUPTIBLE);
+                       prepare_to_wait(&nn->nfsd_ssc_waitq, &wait, TASK_IDLE);
                        spin_unlock(&nn->nfsd_ssc_lock);
 
                        /* allow 20secs for mount/unmount for now - revisit */
-                       if (signal_pending(current) ||
+                       if (kthread_should_stop() ||
                                        (schedule_timeout(20*HZ) == 0)) {
                                finish_wait(&nn->nfsd_ssc_waitq, &wait);
                                kfree(work);

diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
index 4c1a0a1623e5e73cba7dfd4fe88757cb48bce2cc..3d4fd40c987bd7a445845f22c99c4efffe94523b 100644 (file)
--- a/fs/nfsd/nfssvc.c
+++ b/fs/nfsd/nfssvc.c
@@ -938,15 +938,6 @@ nfsd(void *vrqstp)
 
        current->fs->umask = 0;
 
-       /*
-        * thread is spawned with all signals set to SIG_IGN, re-enable
-        * the ones that will bring down the thread
-        */
-       allow_signal(SIGKILL);
-       allow_signal(SIGHUP);
-       allow_signal(SIGINT);
-       allow_signal(SIGQUIT);
-
        atomic_inc(&nfsdstats.th_cnt);
 
        set_freezable();
@@ -971,9 +962,6 @@ nfsd(void *vrqstp)
                validate_process_creds();
        }
 
-       /* Clear signals before calling svc_exit_thread() */
-       flush_signals(current);
-
        atomic_dec(&nfsdstats.th_cnt);
 
 out:

diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
index 67ccf1a6459ae37b0938e079cadad8ab2c0d6e06..b19592673eef2bca6cc19cf11ccc49cbe79b3f4f 100644 (file)
--- a/net/sunrpc/svc_xprt.c
+++ b/net/sunrpc/svc_xprt.c
@@ -700,8 +700,8 @@ static int svc_alloc_arg(struct svc_rqst *rqstp)
                        /* Made progress, don't sleep yet */
                        continue;
 
-               set_current_state(TASK_INTERRUPTIBLE);
-               if (signalled() || kthread_should_stop()) {
+               set_current_state(TASK_IDLE);
+               if (kthread_should_stop()) {
                        set_current_state(TASK_RUNNING);
                        return -EINTR;
                }
@@ -736,7 +736,7 @@ rqst_should_sleep(struct svc_rqst *rqstp)
                return false;
 
        /* are we shutting down? */
-       if (signalled() || kthread_should_stop())
+       if (kthread_should_stop())
                return false;
 
        /* are we freezing? */
@@ -758,11 +758,7 @@ static struct svc_xprt *svc_get_next_xprt(struct svc_rqst *rqstp, long timeout)
        if (rqstp->rq_xprt)
                goto out_found;
 
-       /*
-        * We have to be able to interrupt this wait
-        * to bring down the daemons ...
-        */
-       set_current_state(TASK_INTERRUPTIBLE);
+       set_current_state(TASK_IDLE);
        smp_mb__before_atomic();
        clear_bit(SP_CONGESTED, &pool->sp_flags);
        clear_bit(RQ_BUSY, &rqstp->rq_flags);
@@ -784,7 +780,7 @@ static struct svc_xprt *svc_get_next_xprt(struct svc_rqst *rqstp, long timeout)
        if (!time_left)
                atomic_long_inc(&pool->sp_stats.threads_timedout);
 
-       if (signalled() || kthread_should_stop())
+       if (kthread_should_stop())
                return ERR_PTR(-EINTR);
        return ERR_PTR(-EAGAIN);
 out_found:
@@ -882,7 +878,7 @@ int svc_recv(struct svc_rqst *rqstp, long timeout)
        try_to_freeze();
        cond_resched();
        err = -EINTR;
-       if (signalled() || kthread_should_stop())
+       if (kthread_should_stop())
                goto out;
 
        xprt = svc_get_next_xprt(rqstp, timeout);