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, 534 insertions, 0 deletions

diff --git a/drivers/md/dm-io.c b/drivers/md/dm-io.c
new file mode 100644
index 000000000..777b917be
--- /dev/null
+++ b/drivers/md/dm-io.c
@@ -0,0 +1,534 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2003 Sistina Software
+ * Copyright (C) 2006 Red Hat GmbH
+ *
+ * This file is released under the GPL.
+ */
+
+#include "dm-core.h"
+
+#include <linux/device-mapper.h>
+
+#include <linux/bio.h>
+#include <linux/completion.h>
+#include <linux/mempool.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/dm-io.h>
+
+#define DM_MSG_PREFIX "io"
+
+#define DM_IO_MAX_REGIONS	BITS_PER_LONG
+
+struct dm_io_client {
+	mempool_t pool;
+	struct bio_set bios;
+};
+
+/*
+ * Aligning 'struct io' reduces the number of bits required to store
+ * its address.  Refer to store_io_and_region_in_bio() below.
+ */
+struct io {
+	unsigned long error_bits;
+	unsigned long unsup_bits;
+	atomic_t count;
+	struct dm_io_client *client;
+	io_notify_fn callback;
+	void *context;
+	void *vma_invalidate_address;
+	unsigned long vma_invalidate_size;
+} __aligned(DM_IO_MAX_REGIONS);
+
+static struct kmem_cache *_dm_io_cache;
+
+/*
+ * Create a client with mempool and bioset.
+ */
+struct dm_io_client *dm_io_client_create(void)
+{
+	struct dm_io_client *client;
+	unsigned int min_ios = dm_get_reserved_bio_based_ios();
+	int ret;
+
+	client = kzalloc_obj(*client);
+	if (!client)
+		return ERR_PTR(-ENOMEM);
+
+	ret = mempool_init_slab_pool(&client->pool, min_ios, _dm_io_cache);
+	if (ret)
+		goto bad;
+
+	ret = bioset_init(&client->bios, min_ios, 0, BIOSET_NEED_BVECS);
+	if (ret)
+		goto bad;
+
+	return client;
+
+bad:
+	mempool_exit(&client->pool);
+	kfree(client);
+	return ERR_PTR(ret);
+}
+EXPORT_SYMBOL(dm_io_client_create);
+
+void dm_io_client_destroy(struct dm_io_client *client)
+{
+	mempool_exit(&client->pool);
+	bioset_exit(&client->bios);
+	kfree(client);
+}
+EXPORT_SYMBOL(dm_io_client_destroy);
+
+/*
+ *-------------------------------------------------------------------
+ * We need to keep track of which region a bio is doing io for.
+ * To avoid a memory allocation to store just 5 or 6 bits, we
+ * ensure the 'struct io' pointer is aligned so enough low bits are
+ * always zero and then combine it with the region number directly in
+ * bi_private.
+ *-------------------------------------------------------------------
+ */
+static void store_io_and_region_in_bio(struct bio *bio, struct io *io,
+				       unsigned int region)
+{
+	if (unlikely(!IS_ALIGNED((unsigned long)io, DM_IO_MAX_REGIONS))) {
+		DMCRIT("Unaligned struct io pointer %p", io);
+		BUG();
+	}
+
+	bio->bi_private = (void *)((unsigned long)io | region);
+}
+
+static void retrieve_io_and_region_from_bio(struct bio *bio, struct io **io,
+				       unsigned int *region)
+{
+	unsigned long val = (unsigned long)bio->bi_private;
+
+	*io = (void *)(val & -(unsigned long)DM_IO_MAX_REGIONS);
+	*region = val & (DM_IO_MAX_REGIONS - 1);
+}
+
+/*
+ *--------------------------------------------------------------
+ * We need an io object to keep track of the number of bios that
+ * have been dispatched for a particular io.
+ *--------------------------------------------------------------
+ */
+static void complete_io(struct io *io)
+{
+	unsigned long error_bits = io->error_bits;
+	unsigned long unsup_bits = io->unsup_bits;
+	io_notify_fn fn = io->callback;
+	void *context = io->context;
+
+	if (io->vma_invalidate_size)
+		invalidate_kernel_vmap_range(io->vma_invalidate_address,
+					     io->vma_invalidate_size);
+
+	mempool_free(io, &io->client->pool);
+	fn(error_bits, unsup_bits, context);
+}
+
+static void dec_count(struct io *io, unsigned int region, blk_status_t error)
+{
+	if (unlikely(error)) {
+		if (error == BLK_STS_NOTSUPP || error == BLK_STS_INVAL)
+			set_bit(region, &io->unsup_bits);
+		else
+			set_bit(region, &io->error_bits);
+	}
+
+	if (atomic_dec_and_test(&io->count))
+		complete_io(io);
+}
+
+static void endio(struct bio *bio)
+{
+	struct io *io;
+	unsigned int region;
+	blk_status_t error;
+
+	if (bio->bi_status && bio_data_dir(bio) == READ)
+		zero_fill_bio(bio);
+
+	/*
+	 * The bio destructor in bio_put() may use the io object.
+	 */
+	retrieve_io_and_region_from_bio(bio, &io, &region);
+
+	error = bio->bi_status;
+	bio_put(bio);
+
+	dec_count(io, region, error);
+}
+
+/*
+ *--------------------------------------------------------------
+ * These little objects provide an abstraction for getting a new
+ * destination page for io.
+ *--------------------------------------------------------------
+ */
+struct dpages {
+	void (*get_page)(struct dpages *dp,
+			 struct page **p, unsigned long *len, unsigned int *offset);
+	void (*next_page)(struct dpages *dp);
+
+	unsigned int context_u;
+	void *context_ptr;
+
+	struct bio *orig_bio;
+
+	void *vma_invalidate_address;
+	unsigned long vma_invalidate_size;
+};
+
+/*
+ * Functions for getting the pages from a list.
+ */
+static void list_get_page(struct dpages *dp,
+		  struct page **p, unsigned long *len, unsigned int *offset)
+{
+	unsigned int o = dp->context_u;
+	struct page_list *pl = dp->context_ptr;
+
+	*p = pl->page;
+	*len = PAGE_SIZE - o;
+	*offset = o;
+}
+
+static void list_next_page(struct dpages *dp)
+{
+	struct page_list *pl = dp->context_ptr;
+
+	dp->context_ptr = pl->next;
+	dp->context_u = 0;
+}
+
+static void list_dp_init(struct dpages *dp, struct page_list *pl, unsigned int offset)
+{
+	dp->get_page = list_get_page;
+	dp->next_page = list_next_page;
+	dp->context_u = offset;
+	dp->context_ptr = pl;
+}
+
+/*
+ * Functions for getting the pages from a VMA.
+ */
+static void vm_get_page(struct dpages *dp,
+		 struct page **p, unsigned long *len, unsigned int *offset)
+{
+	*p = vmalloc_to_page(dp->context_ptr);
+	*offset = dp->context_u;
+	*len = PAGE_SIZE - dp->context_u;
+}
+
+static void vm_next_page(struct dpages *dp)
+{
+	dp->context_ptr += PAGE_SIZE - dp->context_u;
+	dp->context_u = 0;
+}
+
+static void vm_dp_init(struct dpages *dp, void *data)
+{
+	dp->get_page = vm_get_page;
+	dp->next_page = vm_next_page;
+	dp->context_u = offset_in_page(data);
+	dp->context_ptr = data;
+}
+
+/*
+ * Functions for getting the pages from kernel memory.
+ */
+static void km_get_page(struct dpages *dp, struct page **p, unsigned long *len,
+			unsigned int *offset)
+{
+	*p = virt_to_page(dp->context_ptr);
+	*offset = dp->context_u;
+	*len = PAGE_SIZE - dp->context_u;
+}
+
+static void km_next_page(struct dpages *dp)
+{
+	dp->context_ptr += PAGE_SIZE - dp->context_u;
+	dp->context_u = 0;
+}
+
+static void km_dp_init(struct dpages *dp, void *data)
+{
+	dp->get_page = km_get_page;
+	dp->next_page = km_next_page;
+	dp->context_u = offset_in_page(data);
+	dp->context_ptr = data;
+}
+
+/*
+ *---------------------------------------------------------------
+ * IO routines that accept a list of pages.
+ *---------------------------------------------------------------
+ */
+static void do_region(const blk_opf_t opf, unsigned int region,
+		      struct dm_io_region *where, struct dpages *dp,
+		      struct io *io, unsigned short ioprio)
+{
+	struct bio *bio;
+	struct page *page;
+	unsigned long len;
+	unsigned int offset;
+	unsigned int num_bvecs;
+	sector_t remaining = where->count;
+	struct request_queue *q = bdev_get_queue(where->bdev);
+	sector_t num_sectors;
+	unsigned int special_cmd_max_sectors;
+	const enum req_op op = opf & REQ_OP_MASK;
+
+	/*
+	 * Reject unsupported discard and write same requests.
+	 */
+	if (op == REQ_OP_DISCARD)
+		special_cmd_max_sectors = bdev_max_discard_sectors(where->bdev);
+	else if (op == REQ_OP_WRITE_ZEROES)
+		special_cmd_max_sectors = q->limits.max_write_zeroes_sectors;
+	if ((op == REQ_OP_DISCARD || op == REQ_OP_WRITE_ZEROES) &&
+	    special_cmd_max_sectors == 0) {
+		atomic_inc(&io->count);
+		dec_count(io, region, BLK_STS_NOTSUPP);
+		return;
+	}
+
+	if (dp->orig_bio) {
+		bio = bio_alloc_clone(where->bdev, dp->orig_bio, GFP_NOIO,
+				      &io->client->bios);
+		bio->bi_iter.bi_sector = where->sector;
+		bio->bi_iter.bi_size = where->count << SECTOR_SHIFT;
+		bio->bi_opf = opf;
+		bio->bi_end_io = endio;
+		bio->bi_ioprio = ioprio;
+		store_io_and_region_in_bio(bio, io, region);
+
+		atomic_inc(&io->count);
+		submit_bio(bio);
+		return;
+	}
+
+	/*
+	 * where->count may be zero if op holds a flush and we need to
+	 * send a zero-sized flush.
+	 */
+	do {
+		/*
+		 * Allocate a suitably sized-bio.
+		 */
+		switch (op) {
+		case REQ_OP_DISCARD:
+		case REQ_OP_WRITE_ZEROES:
+			num_bvecs = 0;
+			break;
+		default:
+			num_bvecs = bio_max_segs(dm_sector_div_up(remaining,
+						(PAGE_SIZE >> SECTOR_SHIFT)) + 1);
+		}
+
+		bio = bio_alloc_bioset(where->bdev, num_bvecs, opf, GFP_NOIO,
+				       &io->client->bios);
+		bio->bi_iter.bi_sector = where->sector + (where->count - remaining);
+		bio->bi_end_io = endio;
+		bio->bi_ioprio = ioprio;
+		store_io_and_region_in_bio(bio, io, region);
+
+		if (op == REQ_OP_DISCARD || op == REQ_OP_WRITE_ZEROES) {
+			num_sectors = min_t(sector_t, special_cmd_max_sectors, remaining);
+			bio->bi_iter.bi_size = num_sectors << SECTOR_SHIFT;
+			remaining -= num_sectors;
+		} else {
+			while (remaining) {
+				/*
+				 * Try and add as many pages as possible.
+				 */
+				dp->get_page(dp, &page, &len, &offset);
+				len = min(len, to_bytes(remaining));
+				if (!bio_add_page(bio, page, len, offset))
+					break;
+
+				offset = 0;
+				remaining -= to_sector(len);
+				dp->next_page(dp);
+			}
+		}
+
+		atomic_inc(&io->count);
+		submit_bio(bio);
+		WARN_ON_ONCE(opf & REQ_ATOMIC && remaining);
+	} while (remaining);
+}
+
+static void dispatch_io(blk_opf_t opf, unsigned int num_regions,
+			struct dm_io_region *where, struct dpages *dp,
+			struct io *io, unsigned short ioprio)
+{
+	int i;
+	struct dpages old_pages = *dp;
+
+	BUG_ON(num_regions > DM_IO_MAX_REGIONS);
+
+	/*
+	 * For multiple regions we need to be careful to rewind
+	 * the dp object for each call to do_region.
+	 */
+	for (i = 0; i < num_regions; i++) {
+		*dp = old_pages;
+		if (where[i].count || (opf & REQ_PREFLUSH))
+			do_region(opf, i, where + i, dp, io, ioprio);
+	}
+
+	/*
+	 * Drop the extra reference that we were holding to avoid
+	 * the io being completed too early.
+	 */
+	dec_count(io, 0, 0);
+}
+
+static void async_io(struct dm_io_client *client, unsigned int num_regions,
+		     struct dm_io_region *where, blk_opf_t opf,
+		     struct dpages *dp, io_notify_fn fn, void *context,
+		     unsigned short ioprio)
+{
+	struct io *io;
+
+	io = mempool_alloc(&client->pool, GFP_NOIO);
+	io->error_bits = 0;
+	io->unsup_bits = 0;
+	atomic_set(&io->count, 1); /* see dispatch_io() */
+	io->client = client;
+	io->callback = fn;
+	io->context = context;
+
+	io->vma_invalidate_address = dp->vma_invalidate_address;
+	io->vma_invalidate_size = dp->vma_invalidate_size;
+
+	dispatch_io(opf, num_regions, where, dp, io, ioprio);
+}
+
+struct sync_io {
+	unsigned long error_bits;
+	unsigned long unsup_bits;
+	struct completion wait;
+};
+
+static void sync_io_complete(unsigned long error, unsigned long unsup, void *context)
+{
+	struct sync_io *sio = context;
+
+	sio->error_bits = error;
+	sio->unsup_bits = unsup;
+	complete(&sio->wait);
+}
+
+static int sync_io(struct dm_io_client *client, unsigned int num_regions,
+		   struct dm_io_region *where, blk_opf_t opf, struct dpages *dp,
+		   unsigned long *error_bits, unsigned long *unsup_bits,
+		   unsigned short ioprio)
+{
+	struct sync_io sio;
+
+	init_completion(&sio.wait);
+
+	async_io(client, num_regions, where, opf | REQ_SYNC, dp,
+		 sync_io_complete, &sio, ioprio);
+
+	wait_for_completion_io(&sio.wait);
+
+	if (error_bits)
+		*error_bits = sio.error_bits;
+	if (unsup_bits)
+		*unsup_bits = sio.unsup_bits;
+
+	return sio.error_bits ? -EIO : sio.unsup_bits ? -EOPNOTSUPP : 0;
+}
+
+static int dp_init(struct dm_io_request *io_req, struct dpages *dp,
+		   unsigned long size)
+{
+	/* Set up dpages based on memory type */
+
+	dp->vma_invalidate_address = NULL;
+	dp->vma_invalidate_size = 0;
+	dp->orig_bio = NULL;
+
+	switch (io_req->mem.type) {
+	case DM_IO_PAGE_LIST:
+		list_dp_init(dp, io_req->mem.ptr.pl, io_req->mem.offset);
+		break;
+
+	case DM_IO_BIO:
+		/*
+		 * The destination bios clone this bio's biovec directly, so
+		 * there are no per-page accessors to set up here.
+		 */
+		dp->orig_bio = io_req->mem.ptr.bio;
+		break;
+
+	case DM_IO_VMA:
+		flush_kernel_vmap_range(io_req->mem.ptr.vma, size);
+		if ((io_req->bi_opf & REQ_OP_MASK) == REQ_OP_READ) {
+			dp->vma_invalidate_address = io_req->mem.ptr.vma;
+			dp->vma_invalidate_size = size;
+		}
+		vm_dp_init(dp, io_req->mem.ptr.vma);
+		break;
+
+	case DM_IO_KMEM:
+		km_dp_init(dp, io_req->mem.ptr.addr);
+		break;
+
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+int dm_io(struct dm_io_request *io_req, unsigned int num_regions,
+	  struct dm_io_region *where, unsigned long *sync_error_bits,
+	  unsigned long *sync_unsup_bits, unsigned short ioprio)
+{
+	int r;
+	struct dpages dp;
+
+	if (num_regions > 1 && !op_is_write(io_req->bi_opf)) {
+		WARN_ON(1);
+		return -EIO;
+	}
+
+	r = dp_init(io_req, &dp, (unsigned long)where->count << SECTOR_SHIFT);
+	if (r)
+		return r;
+
+	if (!io_req->notify.fn)
+		return sync_io(io_req->client, num_regions, where,
+			       io_req->bi_opf, &dp, sync_error_bits,
+			       sync_unsup_bits, ioprio);
+
+	async_io(io_req->client, num_regions, where, io_req->bi_opf, &dp,
+		 io_req->notify.fn, io_req->notify.context, ioprio);
+	return 0;
+}
+EXPORT_SYMBOL(dm_io);
+
+int __init dm_io_init(void)
+{
+	_dm_io_cache = KMEM_CACHE(io, 0);
+	if (!_dm_io_cache)
+		return -ENOMEM;
+
+	return 0;
+}
+
+void dm_io_exit(void)
+{
+	kmem_cache_destroy(_dm_io_cache);
+	_dm_io_cache = NULL;
+}