Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 539 insertions, 0 deletions

diff --git a/fs/afs/fs_probe.c b/fs/afs/fs_probe.c
new file mode 100644
index 000000000..a91ad1938
--- /dev/null
+++ b/fs/afs/fs_probe.c
@@ -0,0 +1,539 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* AFS fileserver probing
+ *
+ * Copyright (C) 2018, 2020 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include "afs_fs.h"
+#include "internal.h"
+#include "protocol_afs.h"
+#include "protocol_yfs.h"
+
+static unsigned int afs_fs_probe_fast_poll_interval = 30 * HZ;
+static unsigned int afs_fs_probe_slow_poll_interval = 5 * 60 * HZ;
+
+struct afs_endpoint_state *afs_get_endpoint_state(struct afs_endpoint_state *estate,
+						  enum afs_estate_trace where)
+{
+	if (estate) {
+		int r;
+
+		__refcount_inc(&estate->ref, &r);
+		trace_afs_estate(estate->server_id, estate->probe_seq, r, where);
+	}
+	return estate;
+}
+
+static void afs_endpoint_state_rcu(struct rcu_head *rcu)
+{
+	struct afs_endpoint_state *estate = container_of(rcu, struct afs_endpoint_state, rcu);
+
+	trace_afs_estate(estate->server_id, estate->probe_seq, refcount_read(&estate->ref),
+			 afs_estate_trace_free);
+	afs_put_addrlist(estate->addresses, afs_alist_trace_put_estate);
+	kfree(estate);
+}
+
+void afs_put_endpoint_state(struct afs_endpoint_state *estate, enum afs_estate_trace where)
+{
+	if (estate) {
+		unsigned int server_id = estate->server_id, probe_seq = estate->probe_seq;
+		bool dead;
+		int r;
+
+		dead = __refcount_dec_and_test(&estate->ref, &r);
+		trace_afs_estate(server_id, probe_seq, r, where);
+		if (dead)
+			call_rcu(&estate->rcu, afs_endpoint_state_rcu);
+	}
+}
+
+/*
+ * Start the probe polling timer.  We have to supply it with an inc on the
+ * outstanding server count.
+ */
+static void afs_schedule_fs_probe(struct afs_net *net,
+				  struct afs_server *server, bool fast)
+{
+	unsigned long atj;
+
+	if (!net->live)
+		return;
+
+	atj = server->probed_at;
+	atj += fast ? afs_fs_probe_fast_poll_interval : afs_fs_probe_slow_poll_interval;
+
+	afs_inc_servers_outstanding(net);
+	if (timer_reduce(&net->fs_probe_timer, atj))
+		afs_dec_servers_outstanding(net);
+}
+
+/*
+ * Handle the completion of a set of probes.
+ */
+static void afs_finished_fs_probe(struct afs_net *net, struct afs_server *server,
+				  struct afs_endpoint_state *estate)
+{
+	bool responded = test_bit(AFS_ESTATE_RESPONDED, &estate->flags);
+
+	write_seqlock(&net->fs_lock);
+	if (responded) {
+		list_add_tail(&server->probe_link, &net->fs_probe_slow);
+	} else {
+		server->rtt = UINT_MAX;
+		clear_bit(AFS_SERVER_FL_RESPONDING, &server->flags);
+		list_add_tail(&server->probe_link, &net->fs_probe_fast);
+	}
+
+	write_sequnlock(&net->fs_lock);
+
+	afs_schedule_fs_probe(net, server, !responded);
+}
+
+/*
+ * Handle the completion of a probe.
+ */
+static void afs_done_one_fs_probe(struct afs_net *net, struct afs_server *server,
+				  struct afs_endpoint_state *estate)
+{
+	_enter("");
+
+	if (atomic_dec_and_test(&estate->nr_probing))
+		afs_finished_fs_probe(net, server, estate);
+
+	wake_up_all(&server->probe_wq);
+}
+
+/*
+ * Handle inability to send a probe due to ENOMEM when trying to allocate a
+ * call struct.
+ */
+static void afs_fs_probe_not_done(struct afs_net *net,
+				  struct afs_server *server,
+				  struct afs_endpoint_state *estate,
+				  int index)
+{
+	_enter("");
+
+	trace_afs_io_error(0, -ENOMEM, afs_io_error_fs_probe_fail);
+	spin_lock(&server->probe_lock);
+
+	set_bit(AFS_ESTATE_LOCAL_FAILURE, &estate->flags);
+	if (estate->error == 0)
+		estate->error = -ENOMEM;
+
+	set_bit(index, &estate->failed_set);
+
+	spin_unlock(&server->probe_lock);
+	return afs_done_one_fs_probe(net, server, estate);
+}
+
+/*
+ * Process the result of probing a fileserver.  This is called after successful
+ * or failed delivery of an FS.GetCapabilities operation.
+ */
+void afs_fileserver_probe_result(struct afs_call *call)
+{
+	struct afs_endpoint_state *estate = call->probe;
+	struct afs_addr_list *alist = estate->addresses;
+	struct afs_address *addr = &alist->addrs[call->probe_index];
+	struct afs_server *server = call->server;
+	unsigned int index = call->probe_index;
+	unsigned int rtt_us = -1, cap0;
+	int ret = call->error;
+
+	_enter("%pU,%u", &server->uuid, index);
+
+	WRITE_ONCE(addr->last_error, ret);
+
+	spin_lock(&server->probe_lock);
+
+	switch (ret) {
+	case 0:
+		estate->error = 0;
+		goto responded;
+	case -ECONNABORTED:
+		if (!test_bit(AFS_ESTATE_RESPONDED, &estate->flags)) {
+			estate->abort_code = call->abort_code;
+			estate->error = ret;
+		}
+		goto responded;
+	case -ENOMEM:
+	case -ENONET:
+		clear_bit(index, &estate->responsive_set);
+		set_bit(AFS_ESTATE_LOCAL_FAILURE, &estate->flags);
+		trace_afs_io_error(call->debug_id, ret, afs_io_error_fs_probe_fail);
+		goto out;
+	case -ECONNRESET: /* Responded, but call expired. */
+	case -ERFKILL:
+	case -EADDRNOTAVAIL:
+	case -ENETUNREACH:
+	case -EHOSTUNREACH:
+	case -EHOSTDOWN:
+	case -ECONNREFUSED:
+	case -ETIMEDOUT:
+	case -ETIME:
+	default:
+		clear_bit(index, &estate->responsive_set);
+		set_bit(index, &estate->failed_set);
+		if (!test_bit(AFS_ESTATE_RESPONDED, &estate->flags) &&
+		    (estate->error == 0 ||
+		     estate->error == -ETIMEDOUT ||
+		     estate->error == -ETIME))
+			estate->error = ret;
+		trace_afs_io_error(call->debug_id, ret, afs_io_error_fs_probe_fail);
+		goto out;
+	}
+
+responded:
+	clear_bit(index, &estate->failed_set);
+
+	if (call->service_id == YFS_FS_SERVICE) {
+		set_bit(AFS_ESTATE_IS_YFS, &estate->flags);
+		set_bit(AFS_SERVER_FL_IS_YFS, &server->flags);
+		server->service_id = call->service_id;
+	} else {
+		set_bit(AFS_ESTATE_NOT_YFS, &estate->flags);
+		if (!test_bit(AFS_ESTATE_IS_YFS, &estate->flags)) {
+			clear_bit(AFS_SERVER_FL_IS_YFS, &server->flags);
+			server->service_id = call->service_id;
+		}
+		cap0 = ntohl(call->tmp);
+		if (cap0 & AFS3_VICED_CAPABILITY_64BITFILES)
+			set_bit(AFS_SERVER_FL_HAS_FS64, &server->flags);
+		else
+			clear_bit(AFS_SERVER_FL_HAS_FS64, &server->flags);
+	}
+
+	rtt_us = rxrpc_kernel_get_srtt(addr->peer);
+	if (rtt_us < estate->rtt) {
+		estate->rtt = rtt_us;
+		server->rtt = rtt_us;
+		alist->preferred = index;
+	}
+
+	smp_wmb(); /* Set rtt before responded. */
+	set_bit(AFS_ESTATE_RESPONDED, &estate->flags);
+	set_bit(index, &estate->responsive_set);
+	set_bit(AFS_SERVER_FL_RESPONDING, &server->flags);
+out:
+	spin_unlock(&server->probe_lock);
+
+	trace_afs_fs_probe(server, false, estate, index, call->error, call->abort_code, rtt_us);
+	_debug("probe[%x] %pU [%u] %pISpc rtt=%d ret=%d",
+	       estate->probe_seq, &server->uuid, index,
+	       rxrpc_kernel_remote_addr(alist->addrs[index].peer),
+	       rtt_us, ret);
+
+	return afs_done_one_fs_probe(call->net, server, estate);
+}
+
+/*
+ * Probe all of a fileserver's addresses to find out the best route and to
+ * query its capabilities.
+ */
+int afs_fs_probe_fileserver(struct afs_net *net, struct afs_server *server,
+			    struct afs_addr_list *new_alist, struct key *key)
+{
+	struct afs_endpoint_state *estate, *old;
+	struct afs_addr_list *old_alist = NULL, *alist;
+	unsigned long unprobed;
+
+	_enter("%pU", &server->uuid);
+
+	estate = kzalloc_obj(*estate);
+	if (!estate)
+		return -ENOMEM;
+
+	refcount_set(&estate->ref, 2);
+	estate->server_id = server->debug_id;
+	estate->rtt = UINT_MAX;
+
+	write_lock(&server->fs_lock);
+
+	old = rcu_dereference_protected(server->endpoint_state,
+					lockdep_is_held(&server->fs_lock));
+	if (old) {
+		estate->responsive_set = old->responsive_set;
+		if (!new_alist)
+			new_alist = old->addresses;
+	}
+
+	if (old_alist != new_alist)
+		afs_set_peer_appdata(server, old_alist, new_alist);
+
+	estate->addresses = afs_get_addrlist(new_alist, afs_alist_trace_get_estate);
+	alist = estate->addresses;
+	estate->probe_seq = ++server->probe_counter;
+	atomic_set(&estate->nr_probing, alist->nr_addrs);
+
+	if (new_alist)
+		server->addr_version = new_alist->version;
+	rcu_assign_pointer(server->endpoint_state, estate);
+	write_unlock(&server->fs_lock);
+	if (old)
+		set_bit(AFS_ESTATE_SUPERSEDED, &old->flags);
+
+	trace_afs_estate(estate->server_id, estate->probe_seq, refcount_read(&estate->ref),
+			 afs_estate_trace_alloc_probe);
+
+	afs_get_address_preferences(net, new_alist);
+
+	server->probed_at = jiffies;
+	unprobed = (1UL << alist->nr_addrs) - 1;
+	while (unprobed) {
+		unsigned int index = 0, i;
+		int best_prio = -1;
+
+		for (i = 0; i < alist->nr_addrs; i++) {
+			if (test_bit(i, &unprobed) &&
+			    alist->addrs[i].prio > best_prio) {
+				index = i;
+				best_prio = alist->addrs[i].prio;
+			}
+		}
+		__clear_bit(index, &unprobed);
+
+		trace_afs_fs_probe(server, true, estate, index, 0, 0, 0);
+		if (!afs_fs_get_capabilities(net, server, estate, index, key))
+			afs_fs_probe_not_done(net, server, estate, index);
+	}
+
+	afs_put_endpoint_state(old, afs_estate_trace_put_probe);
+	afs_put_endpoint_state(estate, afs_estate_trace_put_probe);
+	return 0;
+}
+
+/*
+ * Wait for the first as-yet untried fileserver to respond, for the probe state
+ * to be superseded or for all probes to finish.
+ */
+int afs_wait_for_fs_probes(struct afs_operation *op, struct afs_server_state *states, bool intr)
+{
+	struct afs_endpoint_state *estate;
+	struct afs_server_list *slist = op->server_list;
+	bool still_probing = true;
+	int ret = 0, i;
+
+	_enter("%u", slist->nr_servers);
+
+	for (i = 0; i < slist->nr_servers; i++) {
+		estate = states[i].endpoint_state;
+		if (test_bit(AFS_ESTATE_SUPERSEDED, &estate->flags))
+			return 2;
+		if (atomic_read(&estate->nr_probing))
+			still_probing = true;
+		if (estate->responsive_set & states[i].untried_addrs)
+			return 1;
+	}
+	if (!still_probing)
+		return 0;
+
+	for (i = 0; i < slist->nr_servers; i++)
+		add_wait_queue(&slist->servers[i].server->probe_wq, &states[i].probe_waiter);
+
+	for (;;) {
+		still_probing = false;
+
+		set_current_state(intr ? TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE);
+		for (i = 0; i < slist->nr_servers; i++) {
+			estate = states[i].endpoint_state;
+			if (test_bit(AFS_ESTATE_SUPERSEDED, &estate->flags)) {
+				ret = 2;
+				goto stop;
+			}
+			if (atomic_read(&estate->nr_probing))
+				still_probing = true;
+			if (estate->responsive_set & states[i].untried_addrs) {
+				ret = 1;
+				goto stop;
+			}
+		}
+
+		if (!still_probing || signal_pending(current))
+			goto stop;
+		schedule();
+	}
+
+stop:
+	set_current_state(TASK_RUNNING);
+
+	for (i = 0; i < slist->nr_servers; i++)
+		remove_wait_queue(&slist->servers[i].server->probe_wq, &states[i].probe_waiter);
+
+	if (!ret && signal_pending(current))
+		ret = -ERESTARTSYS;
+	return ret;
+}
+
+/*
+ * Probe timer.  We have an increment on fs_outstanding that we need to pass
+ * along to the work item.
+ */
+void afs_fs_probe_timer(struct timer_list *timer)
+{
+	struct afs_net *net = container_of(timer, struct afs_net, fs_probe_timer);
+
+	if (!net->live || !queue_work(afs_wq, &net->fs_prober))
+		afs_dec_servers_outstanding(net);
+}
+
+/*
+ * Dispatch a probe to a server.
+ */
+static void afs_dispatch_fs_probe(struct afs_net *net, struct afs_server *server)
+	__releases(&net->fs_lock)
+{
+	struct key *key = NULL;
+
+	/* We remove it from the queues here - it will be added back to
+	 * one of the queues on the completion of the probe.
+	 */
+	list_del_init(&server->probe_link);
+
+	afs_get_server(server, afs_server_trace_get_probe);
+	write_sequnlock(&net->fs_lock);
+
+	afs_fs_probe_fileserver(net, server, NULL, key);
+	afs_put_server(net, server, afs_server_trace_put_probe);
+}
+
+/*
+ * Probe a server immediately without waiting for its due time to come
+ * round.  This is used when all of the addresses have been tried.
+ */
+void afs_probe_fileserver(struct afs_net *net, struct afs_server *server)
+{
+	write_seqlock(&net->fs_lock);
+	if (!list_empty(&server->probe_link))
+		return afs_dispatch_fs_probe(net, server);
+	write_sequnlock(&net->fs_lock);
+}
+
+/*
+ * Probe dispatcher to regularly dispatch probes to keep NAT alive.
+ */
+void afs_fs_probe_dispatcher(struct work_struct *work)
+{
+	struct afs_net *net = container_of(work, struct afs_net, fs_prober);
+	struct afs_server *fast, *slow, *server;
+	unsigned long nowj, timer_at, poll_at;
+	bool first_pass = true, set_timer = false;
+
+	if (!net->live) {
+		afs_dec_servers_outstanding(net);
+		return;
+	}
+
+	_enter("");
+
+	if (list_empty(&net->fs_probe_fast) && list_empty(&net->fs_probe_slow)) {
+		afs_dec_servers_outstanding(net);
+		_leave(" [none]");
+		return;
+	}
+
+again:
+	write_seqlock(&net->fs_lock);
+
+	fast = slow = server = NULL;
+	nowj = jiffies;
+	timer_at = nowj + MAX_JIFFY_OFFSET;
+
+	if (!list_empty(&net->fs_probe_fast)) {
+		fast = list_first_entry(&net->fs_probe_fast, struct afs_server, probe_link);
+		poll_at = fast->probed_at + afs_fs_probe_fast_poll_interval;
+		if (time_before(nowj, poll_at)) {
+			timer_at = poll_at;
+			set_timer = true;
+			fast = NULL;
+		}
+	}
+
+	if (!list_empty(&net->fs_probe_slow)) {
+		slow = list_first_entry(&net->fs_probe_slow, struct afs_server, probe_link);
+		poll_at = slow->probed_at + afs_fs_probe_slow_poll_interval;
+		if (time_before(nowj, poll_at)) {
+			if (time_before(poll_at, timer_at))
+			    timer_at = poll_at;
+			set_timer = true;
+			slow = NULL;
+		}
+	}
+
+	server = fast ?: slow;
+	if (server)
+		_debug("probe %pU", &server->uuid);
+
+	if (server && (first_pass || !need_resched())) {
+		afs_dispatch_fs_probe(net, server);
+		first_pass = false;
+		goto again;
+	}
+
+	write_sequnlock(&net->fs_lock);
+
+	if (server) {
+		if (!queue_work(afs_wq, &net->fs_prober))
+			afs_dec_servers_outstanding(net);
+		_leave(" [requeue]");
+	} else if (set_timer) {
+		if (timer_reduce(&net->fs_probe_timer, timer_at))
+			afs_dec_servers_outstanding(net);
+		_leave(" [timer]");
+	} else {
+		afs_dec_servers_outstanding(net);
+		_leave(" [quiesce]");
+	}
+}
+
+/*
+ * Wait for a probe on a particular fileserver to complete for 2s.
+ */
+int afs_wait_for_one_fs_probe(struct afs_server *server, struct afs_endpoint_state *estate,
+			      unsigned long exclude, bool is_intr)
+{
+	struct wait_queue_entry wait;
+	unsigned long timo = 2 * HZ;
+
+	if (atomic_read(&estate->nr_probing) == 0)
+		goto dont_wait;
+
+	init_wait_entry(&wait, 0);
+	for (;;) {
+		prepare_to_wait_event(&server->probe_wq, &wait,
+				      is_intr ? TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE);
+		if (timo == 0 ||
+		    test_bit(AFS_ESTATE_SUPERSEDED, &estate->flags) ||
+		    (estate->responsive_set & ~exclude) ||
+		    atomic_read(&estate->nr_probing) == 0 ||
+		    (is_intr && signal_pending(current)))
+			break;
+		timo = schedule_timeout(timo);
+	}
+
+	finish_wait(&server->probe_wq, &wait);
+
+dont_wait:
+	if (test_bit(AFS_ESTATE_SUPERSEDED, &estate->flags))
+		return 0;
+	if (estate->responsive_set & ~exclude)
+		return 1;
+	if (is_intr && signal_pending(current))
+		return -ERESTARTSYS;
+	if (timo == 0)
+		return -ETIME;
+	return -EDESTADDRREQ;
+}
+
+/*
+ * Clean up the probing when the namespace is killed off.
+ */
+void afs_fs_probe_cleanup(struct afs_net *net)
+{
+	if (timer_delete_sync(&net->fs_probe_timer))
+		afs_dec_servers_outstanding(net);
+}