[GIT PULL] tracing/eventfs: Fixes for 6.8

From: Steven Rostedt
Date: Fri Feb 02 2024 - 17:04:38 EST


Linus,

Tracing and eventfs fixes for v6.8:

- Fix the return code for ring_buffer_poll_wait()
It was returing a -EINVAL instead of EPOLLERR.

- Zero out the tracefs_inode so that all fields are initialized.
The ti->private could have had stale data, but instead of
just initializing it to NULL, clear out the entire structure
when it is allocated.

- Fix a crash in timerlat
The hrtimer was initialized at read and not open, but is
canceled at close. If the file was opened and never read
the close will pass a NULL pointer to hrtime_cancel().

- Rewrite of eventfs.
Linus wrote a patch series to remove the dentry references in the
eventfs_inode and to use ref counting and more of proper VFS
interfaces to make it work.

- Add warning to put_ei() if ei is not set to free. That means
something is about to free it when it shouldn't.

- Restructure the eventfs_inode to make it more compact, and remove
the unused llist field.

- Remove the fsnotify*() funtions for when the inodes were being created
in the lookup code. It doesn't make sense to notify about creation
just because something is being looked up.

- The inode hard link count was not accurate. It was being updated
when a file was looked up. The inodes of directories were updating
their parent inode hard link count every time the inode was created.
That means if memory reclaim cleaned a stale directory inode and
the inode was lookup up again, it would increment the parent inode
again as well. Al Viro said to just have all eventfs directories
have a hard link count of 1. That tells user space not to trust it.


Please pull the latest trace-v6.8-rc2 tree, which can be found at:


git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace.git
trace-v6.8-rc2

Tag SHA1: e80590234dfed2854bbab2689a0ae38626e8f7d6
Head SHA1: ca185770db914869ff9fe773bac5e0e5e4165b83


Daniel Bristot de Oliveira (1):
tracing/timerlat: Move hrtimer_init to timerlat_fd open()

Linus Torvalds (6):
eventfs: Initialize the tracefs inode properly
tracefs: Avoid using the ei->dentry pointer unnecessarily
tracefs: dentry lookup crapectomy
eventfs: Remove unused d_parent pointer field
eventfs: Clean up dentry ops and add revalidate function
eventfs: Get rid of dentry pointers without refcounts

Steven Rostedt (Google) (5):
tracefs: Zero out the tracefs_inode when allocating it
eventfs: Warn if an eventfs_inode is freed without is_freed being set
eventfs: Restructure eventfs_inode structure to be more condensed
eventfs: Remove fsnotify*() functions from lookup()
eventfs: Keep all directory links at 1

Vincent Donnefort (1):
ring-buffer: Clean ring_buffer_poll_wait() error return

----
fs/tracefs/event_inode.c | 568 ++++++++++++-------------------------------
fs/tracefs/inode.c | 102 ++------
fs/tracefs/internal.h | 43 ++--
kernel/trace/ring_buffer.c | 2 +-
kernel/trace/trace_osnoise.c | 6 +-
5 files changed, 195 insertions(+), 526 deletions(-)
---------------------------
diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c
index 1c3dd0ad4660..110e8a272189 100644
--- a/fs/tracefs/event_inode.c
+++ b/fs/tracefs/event_inode.c
@@ -62,6 +62,46 @@ enum {

#define EVENTFS_MODE_MASK (EVENTFS_SAVE_MODE - 1)

+/*
+ * eventfs_inode reference count management.
+ *
+ * NOTE! We count only references from dentries, in the
+ * form 'dentry->d_fsdata'. There are also references from
+ * directory inodes ('ti->private'), but the dentry reference
+ * count is always a superset of the inode reference count.
+ */
+static void release_ei(struct kref *ref)
+{
+ struct eventfs_inode *ei = container_of(ref, struct eventfs_inode, kref);
+
+ WARN_ON_ONCE(!ei->is_freed);
+
+ kfree(ei->entry_attrs);
+ kfree_const(ei->name);
+ kfree_rcu(ei, rcu);
+}
+
+static inline void put_ei(struct eventfs_inode *ei)
+{
+ if (ei)
+ kref_put(&ei->kref, release_ei);
+}
+
+static inline void free_ei(struct eventfs_inode *ei)
+{
+ if (ei) {
+ ei->is_freed = 1;
+ put_ei(ei);
+ }
+}
+
+static inline struct eventfs_inode *get_ei(struct eventfs_inode *ei)
+{
+ if (ei)
+ kref_get(&ei->kref);
+ return ei;
+}
+
static struct dentry *eventfs_root_lookup(struct inode *dir,
struct dentry *dentry,
unsigned int flags);
@@ -156,33 +196,30 @@ static int eventfs_set_attr(struct mnt_idmap *idmap, struct dentry *dentry,
return ret;
}

-static void update_top_events_attr(struct eventfs_inode *ei, struct dentry *dentry)
+static void update_top_events_attr(struct eventfs_inode *ei, struct super_block *sb)
{
- struct inode *inode;
+ struct inode *root;

/* Only update if the "events" was on the top level */
if (!ei || !(ei->attr.mode & EVENTFS_TOPLEVEL))
return;

/* Get the tracefs root inode. */
- inode = d_inode(dentry->d_sb->s_root);
- ei->attr.uid = inode->i_uid;
- ei->attr.gid = inode->i_gid;
+ root = d_inode(sb->s_root);
+ ei->attr.uid = root->i_uid;
+ ei->attr.gid = root->i_gid;
}

static void set_top_events_ownership(struct inode *inode)
{
struct tracefs_inode *ti = get_tracefs(inode);
struct eventfs_inode *ei = ti->private;
- struct dentry *dentry;

/* The top events directory doesn't get automatically updated */
if (!ei || !ei->is_events || !(ei->attr.mode & EVENTFS_TOPLEVEL))
return;

- dentry = ei->dentry;
-
- update_top_events_attr(ei, dentry);
+ update_top_events_attr(ei, inode->i_sb);

if (!(ei->attr.mode & EVENTFS_SAVE_UID))
inode->i_uid = ei->attr.uid;
@@ -233,10 +270,11 @@ static struct eventfs_inode *eventfs_find_events(struct dentry *dentry)
{
struct eventfs_inode *ei;

- mutex_lock(&eventfs_mutex);
do {
- /* The parent always has an ei, except for events itself */
- ei = dentry->d_parent->d_fsdata;
+ // The parent is stable because we do not do renames
+ dentry = dentry->d_parent;
+ // ... and directories always have d_fsdata
+ ei = dentry->d_fsdata;

/*
* If the ei is being freed, the ownership of the children
@@ -246,12 +284,10 @@ static struct eventfs_inode *eventfs_find_events(struct dentry *dentry)
ei = NULL;
break;
}
-
- dentry = ei->dentry;
+ // Walk upwards until you find the events inode
} while (!ei->is_events);
- mutex_unlock(&eventfs_mutex);

- update_top_events_attr(ei, dentry);
+ update_top_events_attr(ei, dentry->d_sb);

return ei;
}
@@ -282,11 +318,10 @@ static void update_inode_attr(struct dentry *dentry, struct inode *inode,
}

/**
- * create_file - create a file in the tracefs filesystem
- * @name: the name of the file to create.
+ * lookup_file - look up a file in the tracefs filesystem
+ * @dentry: the dentry to look up
* @mode: the permission that the file should have.
* @attr: saved attributes changed by user
- * @parent: parent dentry for this file.
* @data: something that the caller will want to get to later on.
* @fop: struct file_operations that should be used for this file.
*
@@ -294,30 +329,25 @@ static void update_inode_attr(struct dentry *dentry, struct inode *inode,
* directory. The inode.i_private pointer will point to @data in the open()
* call.
*/
-static struct dentry *create_file(const char *name, umode_t mode,
+static struct dentry *lookup_file(struct eventfs_inode *parent_ei,
+ struct dentry *dentry,
+ umode_t mode,
struct eventfs_attr *attr,
- struct dentry *parent, void *data,
+ void *data,
const struct file_operations *fop)
{
struct tracefs_inode *ti;
- struct dentry *dentry;
struct inode *inode;

if (!(mode & S_IFMT))
mode |= S_IFREG;

if (WARN_ON_ONCE(!S_ISREG(mode)))
- return NULL;
-
- WARN_ON_ONCE(!parent);
- dentry = eventfs_start_creating(name, parent);
-
- if (IS_ERR(dentry))
- return dentry;
+ return ERR_PTR(-EIO);

inode = tracefs_get_inode(dentry->d_sb);
if (unlikely(!inode))
- return eventfs_failed_creating(dentry);
+ return ERR_PTR(-ENOMEM);

/* If the user updated the directory's attributes, use them */
update_inode_attr(dentry, inode, attr, mode);
@@ -331,32 +361,31 @@ static struct dentry *create_file(const char *name, umode_t mode,

ti = get_tracefs(inode);
ti->flags |= TRACEFS_EVENT_INODE;
- d_instantiate(dentry, inode);
- fsnotify_create(dentry->d_parent->d_inode, dentry);
- return eventfs_end_creating(dentry);
+
+ // Files have their parent's ei as their fsdata
+ dentry->d_fsdata = get_ei(parent_ei);
+
+ d_add(dentry, inode);
+ return NULL;
};

/**
- * create_dir - create a dir in the tracefs filesystem
+ * lookup_dir_entry - look up a dir in the tracefs filesystem
+ * @dentry: the directory to look up
* @ei: the eventfs_inode that represents the directory to create
- * @parent: parent dentry for this file.
*
- * This function will create a dentry for a directory represented by
+ * This function will look up a dentry for a directory represented by
* a eventfs_inode.
*/
-static struct dentry *create_dir(struct eventfs_inode *ei, struct dentry *parent)
+static struct dentry *lookup_dir_entry(struct dentry *dentry,
+ struct eventfs_inode *pei, struct eventfs_inode *ei)
{
struct tracefs_inode *ti;
- struct dentry *dentry;
struct inode *inode;

- dentry = eventfs_start_creating(ei->name, parent);
- if (IS_ERR(dentry))
- return dentry;
-
inode = tracefs_get_inode(dentry->d_sb);
if (unlikely(!inode))
- return eventfs_failed_creating(dentry);
+ return ERR_PTR(-ENOMEM);

/* If the user updated the directory's attributes, use them */
update_inode_attr(dentry, inode, &ei->attr,
@@ -370,64 +399,46 @@ static struct dentry *create_dir(struct eventfs_inode *ei, struct dentry *parent

ti = get_tracefs(inode);
ti->flags |= TRACEFS_EVENT_INODE;
+ /* Only directories have ti->private set to an ei, not files */
+ ti->private = ei;

- inc_nlink(inode);
- d_instantiate(dentry, inode);
- inc_nlink(dentry->d_parent->d_inode);
- fsnotify_mkdir(dentry->d_parent->d_inode, dentry);
- return eventfs_end_creating(dentry);
+ dentry->d_fsdata = get_ei(ei);
+
+ d_add(dentry, inode);
+ return NULL;
}

-static void free_ei(struct eventfs_inode *ei)
+static inline struct eventfs_inode *alloc_ei(const char *name)
{
- kfree_const(ei->name);
- kfree(ei->d_children);
- kfree(ei->entry_attrs);
- kfree(ei);
+ struct eventfs_inode *ei = kzalloc(sizeof(*ei), GFP_KERNEL);
+
+ if (!ei)
+ return NULL;
+
+ ei->name = kstrdup_const(name, GFP_KERNEL);
+ if (!ei->name) {
+ kfree(ei);
+ return NULL;
+ }
+ kref_init(&ei->kref);
+ return ei;
}

/**
- * eventfs_set_ei_status_free - remove the dentry reference from an eventfs_inode
- * @ti: the tracefs_inode of the dentry
+ * eventfs_d_release - dentry is going away
* @dentry: dentry which has the reference to remove.
*
* Remove the association between a dentry from an eventfs_inode.
*/
-void eventfs_set_ei_status_free(struct tracefs_inode *ti, struct dentry *dentry)
+void eventfs_d_release(struct dentry *dentry)
{
- struct eventfs_inode *ei;
- int i;
-
- mutex_lock(&eventfs_mutex);
-
- ei = dentry->d_fsdata;
- if (!ei)
- goto out;
-
- /* This could belong to one of the files of the ei */
- if (ei->dentry != dentry) {
- for (i = 0; i < ei->nr_entries; i++) {
- if (ei->d_children[i] == dentry)
- break;
- }
- if (WARN_ON_ONCE(i == ei->nr_entries))
- goto out;
- ei->d_children[i] = NULL;
- } else if (ei->is_freed) {
- free_ei(ei);
- } else {
- ei->dentry = NULL;
- }
-
- dentry->d_fsdata = NULL;
- out:
- mutex_unlock(&eventfs_mutex);
+ put_ei(dentry->d_fsdata);
}

/**
- * create_file_dentry - create a dentry for a file of an eventfs_inode
+ * lookup_file_dentry - create a dentry for a file of an eventfs_inode
* @ei: the eventfs_inode that the file will be created under
- * @idx: the index into the d_children[] of the @ei
+ * @idx: the index into the entry_attrs[] of the @ei
* @parent: The parent dentry of the created file.
* @name: The name of the file to create
* @mode: The mode of the file.
@@ -438,163 +449,17 @@ void eventfs_set_ei_status_free(struct tracefs_inode *ti, struct dentry *dentry)
* address located at @e_dentry.
*/
static struct dentry *
-create_file_dentry(struct eventfs_inode *ei, int idx,
- struct dentry *parent, const char *name, umode_t mode, void *data,
+lookup_file_dentry(struct dentry *dentry,
+ struct eventfs_inode *ei, int idx,
+ umode_t mode, void *data,
const struct file_operations *fops)
{
struct eventfs_attr *attr = NULL;
- struct dentry **e_dentry = &ei->d_children[idx];
- struct dentry *dentry;
-
- WARN_ON_ONCE(!inode_is_locked(parent->d_inode));

- mutex_lock(&eventfs_mutex);
- if (ei->is_freed) {
- mutex_unlock(&eventfs_mutex);
- return NULL;
- }
- /* If the e_dentry already has a dentry, use it */
- if (*e_dentry) {
- dget(*e_dentry);
- mutex_unlock(&eventfs_mutex);
- return *e_dentry;
- }
-
- /* ei->entry_attrs are protected by SRCU */
if (ei->entry_attrs)
attr = &ei->entry_attrs[idx];

- mutex_unlock(&eventfs_mutex);
-
- dentry = create_file(name, mode, attr, parent, data, fops);
-
- mutex_lock(&eventfs_mutex);
-
- if (IS_ERR_OR_NULL(dentry)) {
- /*
- * When the mutex was released, something else could have
- * created the dentry for this e_dentry. In which case
- * use that one.
- *
- * If ei->is_freed is set, the e_dentry is currently on its
- * way to being freed, don't return it. If e_dentry is NULL
- * it means it was already freed.
- */
- if (ei->is_freed) {
- dentry = NULL;
- } else {
- dentry = *e_dentry;
- dget(dentry);
- }
- mutex_unlock(&eventfs_mutex);
- return dentry;
- }
-
- if (!*e_dentry && !ei->is_freed) {
- *e_dentry = dentry;
- dentry->d_fsdata = ei;
- } else {
- /*
- * Should never happen unless we get here due to being freed.
- * Otherwise it means two dentries exist with the same name.
- */
- WARN_ON_ONCE(!ei->is_freed);
- dentry = NULL;
- }
- mutex_unlock(&eventfs_mutex);
-
- return dentry;
-}
-
-/**
- * eventfs_post_create_dir - post create dir routine
- * @ei: eventfs_inode of recently created dir
- *
- * Map the meta-data of files within an eventfs dir to their parent dentry
- */
-static void eventfs_post_create_dir(struct eventfs_inode *ei)
-{
- struct eventfs_inode *ei_child;
- struct tracefs_inode *ti;
-
- lockdep_assert_held(&eventfs_mutex);
-
- /* srcu lock already held */
- /* fill parent-child relation */
- list_for_each_entry_srcu(ei_child, &ei->children, list,
- srcu_read_lock_held(&eventfs_srcu)) {
- ei_child->d_parent = ei->dentry;
- }
-
- ti = get_tracefs(ei->dentry->d_inode);
- ti->private = ei;
-}
-
-/**
- * create_dir_dentry - Create a directory dentry for the eventfs_inode
- * @pei: The eventfs_inode parent of ei.
- * @ei: The eventfs_inode to create the directory for
- * @parent: The dentry of the parent of this directory
- *
- * This creates and attaches a directory dentry to the eventfs_inode @ei.
- */
-static struct dentry *
-create_dir_dentry(struct eventfs_inode *pei, struct eventfs_inode *ei,
- struct dentry *parent)
-{
- struct dentry *dentry = NULL;
-
- WARN_ON_ONCE(!inode_is_locked(parent->d_inode));
-
- mutex_lock(&eventfs_mutex);
- if (pei->is_freed || ei->is_freed) {
- mutex_unlock(&eventfs_mutex);
- return NULL;
- }
- if (ei->dentry) {
- /* If the eventfs_inode already has a dentry, use it */
- dentry = ei->dentry;
- dget(dentry);
- mutex_unlock(&eventfs_mutex);
- return dentry;
- }
- mutex_unlock(&eventfs_mutex);
-
- dentry = create_dir(ei, parent);
-
- mutex_lock(&eventfs_mutex);
-
- if (IS_ERR_OR_NULL(dentry) && !ei->is_freed) {
- /*
- * When the mutex was released, something else could have
- * created the dentry for this e_dentry. In which case
- * use that one.
- *
- * If ei->is_freed is set, the e_dentry is currently on its
- * way to being freed.
- */
- dentry = ei->dentry;
- if (dentry)
- dget(dentry);
- mutex_unlock(&eventfs_mutex);
- return dentry;
- }
-
- if (!ei->dentry && !ei->is_freed) {
- ei->dentry = dentry;
- eventfs_post_create_dir(ei);
- dentry->d_fsdata = ei;
- } else {
- /*
- * Should never happen unless we get here due to being freed.
- * Otherwise it means two dentries exist with the same name.
- */
- WARN_ON_ONCE(!ei->is_freed);
- dentry = NULL;
- }
- mutex_unlock(&eventfs_mutex);
-
- return dentry;
+ return lookup_file(ei, dentry, mode, attr, data, fops);
}

/**
@@ -611,79 +476,50 @@ static struct dentry *eventfs_root_lookup(struct inode *dir,
struct dentry *dentry,
unsigned int flags)
{
- const struct file_operations *fops;
- const struct eventfs_entry *entry;
struct eventfs_inode *ei_child;
struct tracefs_inode *ti;
struct eventfs_inode *ei;
- struct dentry *ei_dentry = NULL;
- struct dentry *ret = NULL;
- struct dentry *d;
const char *name = dentry->d_name.name;
- umode_t mode;
- void *data;
- int idx;
- int i;
- int r;
+ struct dentry *result = NULL;

ti = get_tracefs(dir);
if (!(ti->flags & TRACEFS_EVENT_INODE))
- return NULL;
+ return ERR_PTR(-EIO);

- /* Grab srcu to prevent the ei from going away */
- idx = srcu_read_lock(&eventfs_srcu);
-
- /*
- * Grab the eventfs_mutex to consistent value from ti->private.
- * This s
- */
mutex_lock(&eventfs_mutex);
- ei = READ_ONCE(ti->private);
- if (ei && !ei->is_freed)
- ei_dentry = READ_ONCE(ei->dentry);
- mutex_unlock(&eventfs_mutex);

- if (!ei || !ei_dentry)
+ ei = ti->private;
+ if (!ei || ei->is_freed)
goto out;

- data = ei->data;
-
- list_for_each_entry_srcu(ei_child, &ei->children, list,
- srcu_read_lock_held(&eventfs_srcu)) {
+ list_for_each_entry(ei_child, &ei->children, list) {
if (strcmp(ei_child->name, name) != 0)
continue;
- ret = simple_lookup(dir, dentry, flags);
- if (IS_ERR(ret))
+ if (ei_child->is_freed)
goto out;
- d = create_dir_dentry(ei, ei_child, ei_dentry);
- dput(d);
+ result = lookup_dir_entry(dentry, ei, ei_child);
goto out;
}

- for (i = 0; i < ei->nr_entries; i++) {
- entry = &ei->entries[i];
- if (strcmp(name, entry->name) == 0) {
- void *cdata = data;
- mutex_lock(&eventfs_mutex);
- /* If ei->is_freed, then the event itself may be too */
- if (!ei->is_freed)
- r = entry->callback(name, &mode, &cdata, &fops);
- else
- r = -1;
- mutex_unlock(&eventfs_mutex);
- if (r <= 0)
- continue;
- ret = simple_lookup(dir, dentry, flags);
- if (IS_ERR(ret))
- goto out;
- d = create_file_dentry(ei, i, ei_dentry, name, mode, cdata, fops);
- dput(d);
- break;
- }
+ for (int i = 0; i < ei->nr_entries; i++) {
+ void *data;
+ umode_t mode;
+ const struct file_operations *fops;
+ const struct eventfs_entry *entry = &ei->entries[i];
+
+ if (strcmp(name, entry->name) != 0)
+ continue;
+
+ data = ei->data;
+ if (entry->callback(name, &mode, &data, &fops) <= 0)
+ goto out;
+
+ result = lookup_file_dentry(dentry, ei, i, mode, data, fops);
+ goto out;
}
out:
- srcu_read_unlock(&eventfs_srcu, idx);
- return ret;
+ mutex_unlock(&eventfs_mutex);
+ return result;
}

/*
@@ -833,25 +669,10 @@ struct eventfs_inode *eventfs_create_dir(const char *name, struct eventfs_inode
if (!parent)
return ERR_PTR(-EINVAL);

- ei = kzalloc(sizeof(*ei), GFP_KERNEL);
+ ei = alloc_ei(name);
if (!ei)
return ERR_PTR(-ENOMEM);

- ei->name = kstrdup_const(name, GFP_KERNEL);
- if (!ei->name) {
- kfree(ei);
- return ERR_PTR(-ENOMEM);
- }
-
- if (size) {
- ei->d_children = kcalloc(size, sizeof(*ei->d_children), GFP_KERNEL);
- if (!ei->d_children) {
- kfree_const(ei->name);
- kfree(ei);
- return ERR_PTR(-ENOMEM);
- }
- }
-
ei->entries = entries;
ei->nr_entries = size;
ei->data = data;
@@ -859,10 +680,8 @@ struct eventfs_inode *eventfs_create_dir(const char *name, struct eventfs_inode
INIT_LIST_HEAD(&ei->list);

mutex_lock(&eventfs_mutex);
- if (!parent->is_freed) {
+ if (!parent->is_freed)
list_add_tail(&ei->list, &parent->children);
- ei->d_parent = parent->dentry;
- }
mutex_unlock(&eventfs_mutex);

/* Was the parent freed? */
@@ -902,28 +721,20 @@ struct eventfs_inode *eventfs_create_events_dir(const char *name, struct dentry
if (IS_ERR(dentry))
return ERR_CAST(dentry);

- ei = kzalloc(sizeof(*ei), GFP_KERNEL);
+ ei = alloc_ei(name);
if (!ei)
- goto fail_ei;
+ goto fail;

inode = tracefs_get_inode(dentry->d_sb);
if (unlikely(!inode))
goto fail;

- if (size) {
- ei->d_children = kcalloc(size, sizeof(*ei->d_children), GFP_KERNEL);
- if (!ei->d_children)
- goto fail;
- }
-
- ei->dentry = dentry;
+ // Note: we have a ref to the dentry from tracefs_start_creating()
+ ei->events_dir = dentry;
ei->entries = entries;
ei->nr_entries = size;
ei->is_events = 1;
ei->data = data;
- ei->name = kstrdup_const(name, GFP_KERNEL);
- if (!ei->name)
- goto fail;

/* Save the ownership of this directory */
uid = d_inode(dentry->d_parent)->i_uid;
@@ -954,11 +765,19 @@ struct eventfs_inode *eventfs_create_events_dir(const char *name, struct dentry
inode->i_op = &eventfs_root_dir_inode_operations;
inode->i_fop = &eventfs_file_operations;

- dentry->d_fsdata = ei;
+ dentry->d_fsdata = get_ei(ei);

- /* directory inodes start off with i_nlink == 2 (for "." entry) */
- inc_nlink(inode);
+ /*
+ * Keep all eventfs directories with i_nlink == 1.
+ * Due to the dynamic nature of the dentry creations and not
+ * wanting to add a pointer to the parent eventfs_inode in the
+ * eventfs_inode structure, keeping the i_nlink in sync with the
+ * number of directories would cause too much complexity for
+ * something not worth much. Keeping directory links at 1
+ * tells userspace not to trust the link number.
+ */
d_instantiate(dentry, inode);
+ /* The dentry of the "events" parent does keep track though */
inc_nlink(dentry->d_parent->d_inode);
fsnotify_mkdir(dentry->d_parent->d_inode, dentry);
tracefs_end_creating(dentry);
@@ -966,72 +785,11 @@ struct eventfs_inode *eventfs_create_events_dir(const char *name, struct dentry
return ei;

fail:
- kfree(ei->d_children);
- kfree(ei);
- fail_ei:
+ free_ei(ei);
tracefs_failed_creating(dentry);
return ERR_PTR(-ENOMEM);
}

-static LLIST_HEAD(free_list);
-
-static void eventfs_workfn(struct work_struct *work)
-{
- struct eventfs_inode *ei, *tmp;
- struct llist_node *llnode;
-
- llnode = llist_del_all(&free_list);
- llist_for_each_entry_safe(ei, tmp, llnode, llist) {
- /* This dput() matches the dget() from unhook_dentry() */
- for (int i = 0; i < ei->nr_entries; i++) {
- if (ei->d_children[i])
- dput(ei->d_children[i]);
- }
- /* This should only get here if it had a dentry */
- if (!WARN_ON_ONCE(!ei->dentry))
- dput(ei->dentry);
- }
-}
-
-static DECLARE_WORK(eventfs_work, eventfs_workfn);
-
-static void free_rcu_ei(struct rcu_head *head)
-{
- struct eventfs_inode *ei = container_of(head, struct eventfs_inode, rcu);
-
- if (ei->dentry) {
- /* Do not free the ei until all references of dentry are gone */
- if (llist_add(&ei->llist, &free_list))
- queue_work(system_unbound_wq, &eventfs_work);
- return;
- }
-
- /* If the ei doesn't have a dentry, neither should its children */
- for (int i = 0; i < ei->nr_entries; i++) {
- WARN_ON_ONCE(ei->d_children[i]);
- }
-
- free_ei(ei);
-}
-
-static void unhook_dentry(struct dentry *dentry)
-{
- if (!dentry)
- return;
- /*
- * Need to add a reference to the dentry that is expected by
- * simple_recursive_removal(), which will include a dput().
- */
- dget(dentry);
-
- /*
- * Also add a reference for the dput() in eventfs_workfn().
- * That is required as that dput() will free the ei after
- * the SRCU grace period is over.
- */
- dget(dentry);
-}
-
/**
* eventfs_remove_rec - remove eventfs dir or file from list
* @ei: eventfs_inode to be removed.
@@ -1044,8 +802,6 @@ static void eventfs_remove_rec(struct eventfs_inode *ei, int level)
{
struct eventfs_inode *ei_child;

- if (!ei)
- return;
/*
* Check recursion depth. It should never be greater than 3:
* 0 - events/
@@ -1057,28 +813,11 @@ static void eventfs_remove_rec(struct eventfs_inode *ei, int level)
return;

/* search for nested folders or files */
- list_for_each_entry_srcu(ei_child, &ei->children, list,
- lockdep_is_held(&eventfs_mutex)) {
- /* Children only have dentry if parent does */
- WARN_ON_ONCE(ei_child->dentry && !ei->dentry);
+ list_for_each_entry(ei_child, &ei->children, list)
eventfs_remove_rec(ei_child, level + 1);
- }
-

- ei->is_freed = 1;
-
- for (int i = 0; i < ei->nr_entries; i++) {
- if (ei->d_children[i]) {
- /* Children only have dentry if parent does */
- WARN_ON_ONCE(!ei->dentry);
- unhook_dentry(ei->d_children[i]);
- }
- }
-
- unhook_dentry(ei->dentry);
-
- list_del_rcu(&ei->list);
- call_srcu(&eventfs_srcu, &ei->rcu, free_rcu_ei);
+ list_del(&ei->list);
+ free_ei(ei);
}

/**
@@ -1089,22 +828,12 @@ static void eventfs_remove_rec(struct eventfs_inode *ei, int level)
*/
void eventfs_remove_dir(struct eventfs_inode *ei)
{
- struct dentry *dentry;
-
if (!ei)
return;

mutex_lock(&eventfs_mutex);
- dentry = ei->dentry;
eventfs_remove_rec(ei, 0);
mutex_unlock(&eventfs_mutex);
-
- /*
- * If any of the ei children has a dentry, then the ei itself
- * must have a dentry.
- */
- if (dentry)
- simple_recursive_removal(dentry, NULL);
}

/**
@@ -1117,7 +846,11 @@ void eventfs_remove_events_dir(struct eventfs_inode *ei)
{
struct dentry *dentry;

- dentry = ei->dentry;
+ dentry = ei->events_dir;
+ if (!dentry)
+ return;
+
+ ei->events_dir = NULL;
eventfs_remove_dir(ei);

/*
@@ -1127,5 +860,6 @@ void eventfs_remove_events_dir(struct eventfs_inode *ei)
* sticks around while the other ei->dentry are created
* and destroyed dynamically.
*/
+ d_invalidate(dentry);
dput(dentry);
}
diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c
index e1b172c0e091..d65ffad4c327 100644
--- a/fs/tracefs/inode.c
+++ b/fs/tracefs/inode.c
@@ -38,8 +38,6 @@ static struct inode *tracefs_alloc_inode(struct super_block *sb)
if (!ti)
return NULL;

- ti->flags = 0;
-
return &ti->vfs_inode;
}

@@ -379,21 +377,30 @@ static const struct super_operations tracefs_super_operations = {
.show_options = tracefs_show_options,
};

-static void tracefs_dentry_iput(struct dentry *dentry, struct inode *inode)
+/*
+ * It would be cleaner if eventfs had its own dentry ops.
+ *
+ * Note that d_revalidate is called potentially under RCU,
+ * so it can't take the eventfs mutex etc. It's fine - if
+ * we open a file just as it's marked dead, things will
+ * still work just fine, and just see the old stale case.
+ */
+static void tracefs_d_release(struct dentry *dentry)
{
- struct tracefs_inode *ti;
+ if (dentry->d_fsdata)
+ eventfs_d_release(dentry);
+}

- if (!dentry || !inode)
- return;
+static int tracefs_d_revalidate(struct dentry *dentry, unsigned int flags)
+{
+ struct eventfs_inode *ei = dentry->d_fsdata;

- ti = get_tracefs(inode);
- if (ti && ti->flags & TRACEFS_EVENT_INODE)
- eventfs_set_ei_status_free(ti, dentry);
- iput(inode);
+ return !(ei && ei->is_freed);
}

static const struct dentry_operations tracefs_dentry_operations = {
- .d_iput = tracefs_dentry_iput,
+ .d_revalidate = tracefs_d_revalidate,
+ .d_release = tracefs_d_release,
};

static int trace_fill_super(struct super_block *sb, void *data, int silent)
@@ -497,75 +504,6 @@ struct dentry *tracefs_end_creating(struct dentry *dentry)
return dentry;
}

-/**
- * eventfs_start_creating - start the process of creating a dentry
- * @name: Name of the file created for the dentry
- * @parent: The parent dentry where this dentry will be created
- *
- * This is a simple helper function for the dynamically created eventfs
- * files. When the directory of the eventfs files are accessed, their
- * dentries are created on the fly. This function is used to start that
- * process.
- */
-struct dentry *eventfs_start_creating(const char *name, struct dentry *parent)
-{
- struct dentry *dentry;
- int error;
-
- /* Must always have a parent. */
- if (WARN_ON_ONCE(!parent))
- return ERR_PTR(-EINVAL);
-
- error = simple_pin_fs(&trace_fs_type, &tracefs_mount,
- &tracefs_mount_count);
- if (error)
- return ERR_PTR(error);
-
- if (unlikely(IS_DEADDIR(parent->d_inode)))
- dentry = ERR_PTR(-ENOENT);
- else
- dentry = lookup_one_len(name, parent, strlen(name));
-
- if (!IS_ERR(dentry) && dentry->d_inode) {
- dput(dentry);
- dentry = ERR_PTR(-EEXIST);
- }
-
- if (IS_ERR(dentry))
- simple_release_fs(&tracefs_mount, &tracefs_mount_count);
-
- return dentry;
-}
-
-/**
- * eventfs_failed_creating - clean up a failed eventfs dentry creation
- * @dentry: The dentry to clean up
- *
- * If after calling eventfs_start_creating(), a failure is detected, the
- * resources created by eventfs_start_creating() needs to be cleaned up. In
- * that case, this function should be called to perform that clean up.
- */
-struct dentry *eventfs_failed_creating(struct dentry *dentry)
-{
- dput(dentry);
- simple_release_fs(&tracefs_mount, &tracefs_mount_count);
- return NULL;
-}
-
-/**
- * eventfs_end_creating - Finish the process of creating a eventfs dentry
- * @dentry: The dentry that has successfully been created.
- *
- * This function is currently just a place holder to match
- * eventfs_start_creating(). In case any synchronization needs to be added,
- * this function will be used to implement that without having to modify
- * the callers of eventfs_start_creating().
- */
-struct dentry *eventfs_end_creating(struct dentry *dentry)
-{
- return dentry;
-}
-
/* Find the inode that this will use for default */
static struct inode *instance_inode(struct dentry *parent, struct inode *inode)
{
@@ -779,7 +717,11 @@ static void init_once(void *foo)
{
struct tracefs_inode *ti = (struct tracefs_inode *) foo;

+ /* inode_init_once() calls memset() on the vfs_inode portion */
inode_init_once(&ti->vfs_inode);
+
+ /* Zero out the rest */
+ memset_after(ti, 0, vfs_inode);
}

static int __init tracefs_init(void)
diff --git a/fs/tracefs/internal.h b/fs/tracefs/internal.h
index 91c2bf0b91d9..beb3dcd0e434 100644
--- a/fs/tracefs/internal.h
+++ b/fs/tracefs/internal.h
@@ -11,9 +11,10 @@ enum {
};

struct tracefs_inode {
+ struct inode vfs_inode;
+ /* The below gets initialized with memset_after(ti, 0, vfs_inode) */
unsigned long flags;
void *private;
- struct inode vfs_inode;
};

/*
@@ -31,43 +32,37 @@ struct eventfs_attr {
/*
* struct eventfs_inode - hold the properties of the eventfs directories.
* @list: link list into the parent directory
+ * @rcu: Union with @list for freeing
+ * @children: link list into the child eventfs_inode
* @entries: the array of entries representing the files in the directory
* @name: the name of the directory to create
- * @children: link list into the child eventfs_inode
- * @dentry: the dentry of the directory
- * @d_parent: pointer to the parent's dentry
- * @d_children: The array of dentries to represent the files when created
+ * @events_dir: the dentry of the events directory
* @entry_attrs: Saved mode and ownership of the @d_children
- * @attr: Saved mode and ownership of eventfs_inode itself
* @data: The private data to pass to the callbacks
+ * @attr: Saved mode and ownership of eventfs_inode itself
* @is_freed: Flag set if the eventfs is on its way to be freed
* Note if is_freed is set, then dentry is corrupted.
+ * @is_events: Flag set for only the top level "events" directory
* @nr_entries: The number of items in @entries
+ * @ino: The saved inode number
*/
struct eventfs_inode {
- struct list_head list;
+ union {
+ struct list_head list;
+ struct rcu_head rcu;
+ };
+ struct list_head children;
const struct eventfs_entry *entries;
const char *name;
- struct list_head children;
- struct dentry *dentry; /* Check is_freed to access */
- struct dentry *d_parent;
- struct dentry **d_children;
+ struct dentry *events_dir;
struct eventfs_attr *entry_attrs;
- struct eventfs_attr attr;
void *data;
+ struct eventfs_attr attr;
+ struct kref kref;
unsigned int is_freed:1;
unsigned int is_events:1;
unsigned int nr_entries:30;
unsigned int ino;
- /*
- * Union - used for deletion
- * @llist: for calling dput() if needed after RCU
- * @rcu: eventfs_inode to delete in RCU
- */
- union {
- struct llist_node llist;
- struct rcu_head rcu;
- };
};

static inline struct tracefs_inode *get_tracefs(const struct inode *inode)
@@ -79,9 +74,7 @@ struct dentry *tracefs_start_creating(const char *name, struct dentry *parent);
struct dentry *tracefs_end_creating(struct dentry *dentry);
struct dentry *tracefs_failed_creating(struct dentry *dentry);
struct inode *tracefs_get_inode(struct super_block *sb);
-struct dentry *eventfs_start_creating(const char *name, struct dentry *parent);
-struct dentry *eventfs_failed_creating(struct dentry *dentry);
-struct dentry *eventfs_end_creating(struct dentry *dentry);
-void eventfs_set_ei_status_free(struct tracefs_inode *ti, struct dentry *dentry);
+
+void eventfs_d_release(struct dentry *dentry);

#endif /* _TRACEFS_INTERNAL_H */
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 13aaf5e85b81..fd4bfe3ecf01 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -944,7 +944,7 @@ __poll_t ring_buffer_poll_wait(struct trace_buffer *buffer, int cpu,
full = 0;
} else {
if (!cpumask_test_cpu(cpu, buffer->cpumask))
- return -EINVAL;
+ return EPOLLERR;

cpu_buffer = buffer->buffers[cpu];
work = &cpu_buffer->irq_work;
diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c
index bd0d01d00fb9..a8e28f9b9271 100644
--- a/kernel/trace/trace_osnoise.c
+++ b/kernel/trace/trace_osnoise.c
@@ -2444,6 +2444,9 @@ static int timerlat_fd_open(struct inode *inode, struct file *file)
tlat = this_cpu_tmr_var();
tlat->count = 0;

+ hrtimer_init(&tlat->timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS_PINNED_HARD);
+ tlat->timer.function = timerlat_irq;
+
migrate_enable();
return 0;
};
@@ -2526,9 +2529,6 @@ timerlat_fd_read(struct file *file, char __user *ubuf, size_t count,
tlat->tracing_thread = false;
tlat->kthread = current;

- hrtimer_init(&tlat->timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS_PINNED_HARD);
- tlat->timer.function = timerlat_irq;
-
/* Annotate now to drift new period */
tlat->abs_period = hrtimer_cb_get_time(&tlat->timer);