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, 470 insertions, 0 deletions

diff --git a/drivers/md/dm-delay.c b/drivers/md/dm-delay.c
new file mode 100644
index 000000000..4864671c2
--- /dev/null
+++ b/drivers/md/dm-delay.c
@@ -0,0 +1,470 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2005-2007 Red Hat GmbH
+ *
+ * A target that delays reads and/or writes and can send
+ * them to different devices.
+ *
+ * This file is released under the GPL.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/blkdev.h>
+#include <linux/bio.h>
+#include <linux/slab.h>
+#include <linux/kthread.h>
+#include <linux/delay.h>
+
+#include <linux/device-mapper.h>
+
+#define DM_MSG_PREFIX "delay"
+
+#define SLEEP_SHIFT 3
+
+struct delay_class {
+	struct dm_dev *dev;
+	sector_t start;
+	unsigned int delay;
+	unsigned int ops;
+};
+
+struct delay_c {
+	struct timer_list delay_timer;
+	struct mutex process_bios_lock; /* hold while removing bios to be processed from list */
+	spinlock_t delayed_bios_lock; /* hold on all accesses to delayed_bios list */
+	struct workqueue_struct *kdelayd_wq;
+	struct work_struct flush_expired_bios;
+	struct list_head delayed_bios;
+	struct task_struct *worker;
+	unsigned int worker_sleep_us;
+	bool may_delay;
+
+	struct delay_class read;
+	struct delay_class write;
+	struct delay_class flush;
+
+	int argc;
+};
+
+struct dm_delay_info {
+	struct delay_c *context;
+	struct delay_class *class;
+	struct list_head list;
+	unsigned long expires;
+};
+
+static void handle_delayed_timer(struct timer_list *t)
+{
+	struct delay_c *dc = timer_container_of(dc, t, delay_timer);
+
+	queue_work(dc->kdelayd_wq, &dc->flush_expired_bios);
+}
+
+static void queue_timeout(struct delay_c *dc, unsigned long expires)
+{
+	timer_reduce(&dc->delay_timer, expires);
+}
+
+static inline bool delay_is_fast(struct delay_c *dc)
+{
+	return !!dc->worker;
+}
+
+static void flush_bios(struct bio *bio)
+{
+	struct bio *n;
+
+	while (bio) {
+		n = bio->bi_next;
+		bio->bi_next = NULL;
+		dm_submit_bio_remap(bio, NULL);
+		bio = n;
+	}
+}
+
+static void flush_delayed_bios(struct delay_c *dc, bool flush_all)
+{
+	struct dm_delay_info *delayed, *next;
+	struct bio_list flush_bio_list;
+	LIST_HEAD(local_list);
+	unsigned long next_expires = 0;
+	bool start_timer = false;
+	bio_list_init(&flush_bio_list);
+
+	mutex_lock(&dc->process_bios_lock);
+	spin_lock(&dc->delayed_bios_lock);
+	list_replace_init(&dc->delayed_bios, &local_list);
+	spin_unlock(&dc->delayed_bios_lock);
+	list_for_each_entry_safe(delayed, next, &local_list, list) {
+		cond_resched();
+		if (flush_all || time_after_eq(jiffies, delayed->expires)) {
+			struct bio *bio = dm_bio_from_per_bio_data(delayed,
+						sizeof(struct dm_delay_info));
+			list_del(&delayed->list);
+			bio_list_add(&flush_bio_list, bio);
+			delayed->class->ops--;
+			continue;
+		}
+
+		if (!delay_is_fast(dc)) {
+			if (!start_timer) {
+				start_timer = true;
+				next_expires = delayed->expires;
+			} else {
+				next_expires = min(next_expires, delayed->expires);
+			}
+		}
+	}
+	spin_lock(&dc->delayed_bios_lock);
+	list_splice(&local_list, &dc->delayed_bios);
+	spin_unlock(&dc->delayed_bios_lock);
+	mutex_unlock(&dc->process_bios_lock);
+
+	if (start_timer)
+		queue_timeout(dc, next_expires);
+
+	flush_bios(bio_list_get(&flush_bio_list));
+}
+
+static int flush_worker_fn(void *data)
+{
+	struct delay_c *dc = data;
+
+	while (!kthread_should_stop()) {
+		flush_delayed_bios(dc, false);
+		spin_lock(&dc->delayed_bios_lock);
+		if (unlikely(list_empty(&dc->delayed_bios))) {
+			set_current_state(TASK_INTERRUPTIBLE);
+			spin_unlock(&dc->delayed_bios_lock);
+			schedule();
+		} else {
+			spin_unlock(&dc->delayed_bios_lock);
+			fsleep(dc->worker_sleep_us);
+			cond_resched();
+		}
+	}
+
+	return 0;
+}
+
+static void flush_expired_bios(struct work_struct *work)
+{
+	struct delay_c *dc;
+
+	dc = container_of(work, struct delay_c, flush_expired_bios);
+	flush_delayed_bios(dc, false);
+}
+
+static void delay_dtr(struct dm_target *ti)
+{
+	struct delay_c *dc = ti->private;
+
+	if (dc->kdelayd_wq) {
+		timer_shutdown_sync(&dc->delay_timer);
+		destroy_workqueue(dc->kdelayd_wq);
+	}
+
+	if (dc->read.dev)
+		dm_put_device(ti, dc->read.dev);
+	if (dc->write.dev)
+		dm_put_device(ti, dc->write.dev);
+	if (dc->flush.dev)
+		dm_put_device(ti, dc->flush.dev);
+	if (dc->worker)
+		kthread_stop(dc->worker);
+
+	mutex_destroy(&dc->process_bios_lock);
+
+	kfree(dc);
+}
+
+static int delay_class_ctr(struct dm_target *ti, struct delay_class *c, char **argv)
+{
+	int ret;
+	unsigned long long tmpll;
+	char dummy;
+
+	if (sscanf(argv[1], "%llu%c", &tmpll, &dummy) != 1 || tmpll != (sector_t)tmpll) {
+		ti->error = "Invalid device sector";
+		return -EINVAL;
+	}
+	c->start = tmpll;
+
+	if (sscanf(argv[2], "%u%c", &c->delay, &dummy) != 1) {
+		ti->error = "Invalid delay";
+		return -EINVAL;
+	}
+
+	ret = dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &c->dev);
+	if (ret) {
+		ti->error = "Device lookup failed";
+		return ret;
+	}
+
+	return 0;
+}
+
+/*
+ * Mapping parameters:
+ *    <device> <offset> <delay> [<write_device> <write_offset> <write_delay>]
+ *
+ * With separate write parameters, the first set is only used for reads.
+ * Offsets are specified in sectors.
+ * Delays are specified in milliseconds.
+ */
+static int delay_ctr(struct dm_target *ti, unsigned int argc, char **argv)
+{
+	struct delay_c *dc;
+	int ret;
+	unsigned int max_delay, min_delay;
+
+	if (argc != 3 && argc != 6 && argc != 9) {
+		ti->error = "Requires exactly 3, 6 or 9 arguments";
+		return -EINVAL;
+	}
+
+	dc = kzalloc_obj(*dc);
+	if (!dc) {
+		ti->error = "Cannot allocate context";
+		return -ENOMEM;
+	}
+
+	ti->private = dc;
+	INIT_LIST_HEAD(&dc->delayed_bios);
+	mutex_init(&dc->process_bios_lock);
+	spin_lock_init(&dc->delayed_bios_lock);
+	dc->may_delay = true;
+	dc->argc = argc;
+
+	ret = delay_class_ctr(ti, &dc->read, argv);
+	if (ret)
+		goto bad;
+	min_delay = max_delay = dc->read.delay;
+
+	if (argc == 3) {
+		ret = delay_class_ctr(ti, &dc->write, argv);
+		if (ret)
+			goto bad;
+		ret = delay_class_ctr(ti, &dc->flush, argv);
+		if (ret)
+			goto bad;
+		goto out;
+	}
+
+	ret = delay_class_ctr(ti, &dc->write, argv + 3);
+	if (ret)
+		goto bad;
+	max_delay = max(max_delay, dc->write.delay);
+	min_delay = min_not_zero(min_delay, dc->write.delay);
+
+	if (argc == 6) {
+		ret = delay_class_ctr(ti, &dc->flush, argv + 3);
+		if (ret)
+			goto bad;
+		goto out;
+	}
+
+	ret = delay_class_ctr(ti, &dc->flush, argv + 6);
+	if (ret)
+		goto bad;
+	max_delay = max(max_delay, dc->flush.delay);
+	min_delay = min_not_zero(min_delay, dc->flush.delay);
+
+out:
+	if (max_delay < 50) {
+		if (min_delay >> SLEEP_SHIFT)
+			dc->worker_sleep_us = 1000;
+		else
+			dc->worker_sleep_us = (min_delay * 1000) >> SLEEP_SHIFT;
+		/*
+		 * In case of small requested delays, use kthread instead of
+		 * timers and workqueue to achieve better latency.
+		 */
+		dc->worker = kthread_run(&flush_worker_fn, dc, "dm-delay-flush-worker");
+		if (IS_ERR(dc->worker)) {
+			ret = PTR_ERR(dc->worker);
+			dc->worker = NULL;
+			goto bad;
+		}
+	} else {
+		timer_setup(&dc->delay_timer, handle_delayed_timer, 0);
+		INIT_WORK(&dc->flush_expired_bios, flush_expired_bios);
+		dc->kdelayd_wq = alloc_workqueue("kdelayd",
+						 WQ_MEM_RECLAIM | WQ_PERCPU,
+						 0);
+		if (!dc->kdelayd_wq) {
+			ret = -EINVAL;
+			DMERR("Couldn't start kdelayd");
+			goto bad;
+		}
+	}
+
+	ti->num_flush_bios = 1;
+	ti->num_discard_bios = 1;
+	ti->accounts_remapped_io = true;
+	ti->per_io_data_size = sizeof(struct dm_delay_info);
+	return 0;
+
+bad:
+	delay_dtr(ti);
+	return ret;
+}
+
+static int delay_bio(struct delay_c *dc, struct delay_class *c, struct bio *bio)
+{
+	struct dm_delay_info *delayed;
+	unsigned long expires = 0;
+
+	if (!c->delay)
+		return DM_MAPIO_REMAPPED;
+
+	delayed = dm_per_bio_data(bio, sizeof(struct dm_delay_info));
+
+	delayed->context = dc;
+	delayed->expires = expires = jiffies + msecs_to_jiffies(c->delay);
+
+	spin_lock(&dc->delayed_bios_lock);
+	if (unlikely(!dc->may_delay)) {
+		spin_unlock(&dc->delayed_bios_lock);
+		return DM_MAPIO_REMAPPED;
+	}
+	c->ops++;
+	list_add_tail(&delayed->list, &dc->delayed_bios);
+	spin_unlock(&dc->delayed_bios_lock);
+
+	if (delay_is_fast(dc))
+		wake_up_process(dc->worker);
+	else
+		queue_timeout(dc, expires);
+
+	return DM_MAPIO_SUBMITTED;
+}
+
+static void delay_presuspend(struct dm_target *ti)
+{
+	struct delay_c *dc = ti->private;
+
+	spin_lock(&dc->delayed_bios_lock);
+	dc->may_delay = false;
+	spin_unlock(&dc->delayed_bios_lock);
+
+	if (!delay_is_fast(dc))
+		timer_delete(&dc->delay_timer);
+	flush_delayed_bios(dc, true);
+}
+
+static void delay_resume(struct dm_target *ti)
+{
+	struct delay_c *dc = ti->private;
+
+	dc->may_delay = true;
+}
+
+static int delay_map(struct dm_target *ti, struct bio *bio)
+{
+	struct delay_c *dc = ti->private;
+	struct delay_class *c;
+	struct dm_delay_info *delayed = dm_per_bio_data(bio, sizeof(struct dm_delay_info));
+
+	if (bio_data_dir(bio) == WRITE) {
+		if (unlikely(bio->bi_opf & REQ_PREFLUSH))
+			c = &dc->flush;
+		else
+			c = &dc->write;
+	} else {
+		c = &dc->read;
+	}
+	delayed->class = c;
+	bio_set_dev(bio, c->dev->bdev);
+	bio->bi_iter.bi_sector = c->start + dm_target_offset(ti, bio->bi_iter.bi_sector);
+
+	return delay_bio(dc, c, bio);
+}
+
+#ifdef CONFIG_BLK_DEV_ZONED
+static int delay_report_zones(struct dm_target *ti,
+		struct dm_report_zones_args *args, unsigned int nr_zones)
+{
+	struct delay_c *dc = ti->private;
+	struct delay_class *c = &dc->read;
+
+	return dm_report_zones(c->dev->bdev, c->start,
+			c->start + dm_target_offset(ti, args->next_sector),
+			args, nr_zones);
+}
+#else
+#define delay_report_zones	NULL
+#endif
+
+#define DMEMIT_DELAY_CLASS(c) \
+	DMEMIT("%s %llu %u", (c)->dev->name, (unsigned long long)(c)->start, (c)->delay)
+
+static void delay_status(struct dm_target *ti, status_type_t type,
+			 unsigned int status_flags, char *result, unsigned int maxlen)
+{
+	struct delay_c *dc = ti->private;
+	int sz = 0;
+
+	switch (type) {
+	case STATUSTYPE_INFO:
+		DMEMIT("%u %u %u", dc->read.ops, dc->write.ops, dc->flush.ops);
+		break;
+
+	case STATUSTYPE_TABLE:
+		DMEMIT_DELAY_CLASS(&dc->read);
+		if (dc->argc >= 6) {
+			DMEMIT(" ");
+			DMEMIT_DELAY_CLASS(&dc->write);
+		}
+		if (dc->argc >= 9) {
+			DMEMIT(" ");
+			DMEMIT_DELAY_CLASS(&dc->flush);
+		}
+		break;
+
+	case STATUSTYPE_IMA:
+		*result = '\0';
+		break;
+	}
+}
+
+static int delay_iterate_devices(struct dm_target *ti,
+				 iterate_devices_callout_fn fn, void *data)
+{
+	struct delay_c *dc = ti->private;
+	int ret = 0;
+
+	ret = fn(ti, dc->read.dev, dc->read.start, ti->len, data);
+	if (ret)
+		goto out;
+	ret = fn(ti, dc->write.dev, dc->write.start, ti->len, data);
+	if (ret)
+		goto out;
+	ret = fn(ti, dc->flush.dev, dc->flush.start, ti->len, data);
+	if (ret)
+		goto out;
+
+out:
+	return ret;
+}
+
+static struct target_type delay_target = {
+	.name	     = "delay",
+	.version     = {1, 5, 0},
+	.features    = DM_TARGET_PASSES_INTEGRITY | DM_TARGET_ZONED_HM,
+	.module      = THIS_MODULE,
+	.ctr	     = delay_ctr,
+	.dtr	     = delay_dtr,
+	.map	     = delay_map,
+	.report_zones = delay_report_zones,
+	.presuspend  = delay_presuspend,
+	.resume	     = delay_resume,
+	.status	     = delay_status,
+	.iterate_devices = delay_iterate_devices,
+};
+module_dm(delay);
+
+MODULE_DESCRIPTION(DM_NAME " delay target");
+MODULE_AUTHOR("Heinz Mauelshagen <mauelshagen@redhat.com>");
+MODULE_LICENSE("GPL");