From: "Steven Rostedt (Google)" rostedt@goodmis.org

The creation of the trace event directory requires that a TRACE_SYSTEM is defined that the trace event directory is added within the system it was defined in.

The code handled the case where a TRACE_SYSTEM was not added, and would then add the event at the events directory. But nothing should be doing this. This code also prevents the implementation of creating dynamic dentrys for the eventfs system.

As this path has never been hit on correct code, remove it. If it does get hit, issues a WARN_ON_ONCE() and return ENODEV.

Signed-off-by: Steven Rostedt (Google) rostedt@goodmis.org Signed-off-by: Ajay Kaher akaher@vmware.com --- kernel/trace/trace_events.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index 654ffa404..16bc5ba45 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -2424,14 +2424,15 @@ event_create_dir(struct dentry *parent, struct trace_event_file *file)

/* * If the trace point header did not define TRACE_SYSTEM - * then the system would be called "TRACE_SYSTEM". + * then the system would be called "TRACE_SYSTEM". This should + * never happen. */ - if (strcmp(call->class->system, TRACE_SYSTEM) != 0) { - d_events = event_subsystem_dir(tr, call->class->system, file, parent); - if (!d_events) - return -ENOMEM; - } else - d_events = parent; + if (WARN_ON_ONCE(strcmp(call->class->system, TRACE_SYSTEM) == 0)) + return -ENODEV; + + d_events = event_subsystem_dir(tr, call->class->system, file, parent); + if (!d_events) + return -ENOMEM;

name = trace_event_name(call); file->dir = tracefs_create_dir(name, d_events);

Adding eventfs_file structure which will hold properties of file or dir.

Adding following functions to add dir in eventfs:

eventfs_create_events_dir() directly creates events dir with-in tracing folder.

eventfs_add_subsystem_dir() adds the information of subsystem_dir to eventfs and dynamically creates subsystem_dir as and when requires.

eventfs_add_dir() adds the information of dir (which is with-in subsystem_dir) to eventfs and dynamically creates these dir as and when requires.

Signed-off-by: Ajay Kaher akaher@vmware.com Co-developed-by: Steven Rostedt (VMware) rostedt@goodmis.org Signed-off-by: Steven Rostedt (VMware) rostedt@goodmis.org Tested-by: Ching-lin Yu chinglinyu@google.com Reported-by: kernel test robot lkp@intel.com Link: https://lore.kernel.org/oe-lkp/202305051619.9a469a9a-yujie.liu@intel.com --- fs/tracefs/Makefile | 1 + fs/tracefs/event_inode.c | 272 +++++++++++++++++++++++++++++++++++++++ include/linux/tracefs.h | 29 +++++ kernel/trace/trace.h | 1 + 4 files changed, 303 insertions(+) create mode 100644 fs/tracefs/event_inode.c

diff --git a/fs/tracefs/Makefile b/fs/tracefs/Makefile index 7c35a282b..73c56da8e 100644 --- a/fs/tracefs/Makefile +++ b/fs/tracefs/Makefile @@ -1,5 +1,6 @@ # SPDX-License-Identifier: GPL-2.0-only tracefs-objs := inode.o +tracefs-objs += event_inode.o

obj-$(CONFIG_TRACING) += tracefs.o

diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c new file mode 100644 index 000000000..a48ce23c0 --- /dev/null +++ b/fs/tracefs/event_inode.c @@ -0,0 +1,272 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * event_inode.c - part of tracefs, a pseudo file system for activating tracing + * + * Copyright (C) 2020-22 VMware Inc, author: Steven Rostedt (VMware) rostedt@goodmis.org + * Copyright (C) 2020-22 VMware Inc, author: Ajay Kaher akaher@vmware.com + * + * eventfs is used to show trace events with one set of dentries + * + * eventfs stores meta-data of files/dirs and skip to create object of + * inodes/dentries. As and when requires, eventfs will create the + * inodes/dentries for only required files/directories. Also eventfs + * would delete the inodes/dentries once no more requires but preserve + * the meta data. + */ +#include <linux/fsnotify.h> +#include <linux/fs.h> +#include <linux/namei.h> +#include <linux/security.h> +#include <linux/tracefs.h> +#include <linux/kref.h> +#include <linux/delay.h> +#include "internal.h" + +/** + * eventfs_dentry_to_rwsem - Return corresponding eventfs_rwsem + * @dentry: a pointer to dentry + * + * helper function to return crossponding eventfs_rwsem for given dentry + */ +static struct rw_semaphore *eventfs_dentry_to_rwsem(struct dentry *dentry) +{ + if (S_ISDIR(dentry->d_inode->i_mode)) + return (struct rw_semaphore *)dentry->d_inode->i_private; + else + return (struct rw_semaphore *)dentry->d_parent->d_inode->i_private; +} + +/** + * eventfs_down_read - acquire read lock function + * @eventfs_rwsem: a pointer to rw_semaphore + * + * helper function to perform read lock. Nested locking requires because + * lookup(), release() requires read lock, these could be called directly + * or from open(), remove() which already hold the read/write lock. + */ +static void eventfs_down_read(struct rw_semaphore *eventfs_rwsem) +{ + down_read_nested(eventfs_rwsem, SINGLE_DEPTH_NESTING); +} + +/** + * eventfs_up_read - release read lock function + * @eventfs_rwsem: a pointer to rw_semaphore + * + * helper function to release eventfs_rwsem lock if locked + */ +static void eventfs_up_read(struct rw_semaphore *eventfs_rwsem) +{ + up_read(eventfs_rwsem); +} + +/** + * eventfs_down_write - acquire write lock function + * @eventfs_rwsem: a pointer to rw_semaphore + * + * helper function to perform write lock on eventfs_rwsem + */ +static void eventfs_down_write(struct rw_semaphore *eventfs_rwsem) +{ + while (!down_write_trylock(eventfs_rwsem)) + msleep(10); +} + +/** + * eventfs_up_write - release write lock function + * @eventfs_rwsem: a pointer to rw_semaphore + * + * helper function to perform write lock on eventfs_rwsem + */ +static void eventfs_up_write(struct rw_semaphore *eventfs_rwsem) +{ + up_write(eventfs_rwsem); +} + +static const struct file_operations eventfs_file_operations = { +}; + +static const struct inode_operations eventfs_root_dir_inode_operations = { +}; + +/** + * eventfs_prepare_ef - helper function to prepare eventfs_file + * @name: a pointer to a string containing the name of the file/directory + * to create. + * @mode: the permission that the file should have. + * @fop: a pointer to a struct file_operations that should be used for + * this file/directory. + * @iop: a pointer to a struct inode_operations that should be used for + * this file/directory. + * @data: a pointer to something that the caller will want to get to later + * on. The inode.i_private pointer will point to this value on + * the open() call. + * + * This function allocate the fill eventfs_file structure. + */ +static struct eventfs_file *eventfs_prepare_ef(const char *name, umode_t mode, + const struct file_operations *fop, + const struct inode_operations *iop, + void *data) +{ + struct eventfs_file *ef; + + ef = kzalloc(sizeof(*ef), GFP_KERNEL); + if (!ef) + return ERR_PTR(-ENOMEM); + + ef->name = kstrdup(name, GFP_KERNEL); + if (!ef->name) { + kfree(ef); + return ERR_PTR(-ENOMEM); + } + + if (S_ISDIR(mode)) { + ef->ei = kzalloc(sizeof(*ef->ei), GFP_KERNEL); + if (!ef->ei) { + kfree(ef->name); + kfree(ef); + return ERR_PTR(-ENOMEM); + } + INIT_LIST_HEAD(&ef->ei->e_top_files); + } else { + ef->ei = NULL; + } + + ef->iop = iop; + ef->fop = fop; + ef->mode = mode; + ef->data = data; + ef->dentry = NULL; + ef->d_parent = NULL; + ef->created = false; + return ef; +} + +/** + * eventfs_create_events_dir - create the trace event structure + * @name: a pointer to a string containing the name of the directory to + * create. + * @parent: a pointer to the parent dentry for this file. This should be a + * directory dentry if set. If this parameter is NULL, then the + * directory will be created in the root of the tracefs filesystem. + * @eventfs_rwsem: a pointer to rw_semaphore + * + * This function creates the top of the trace event directory. + */ +struct dentry *eventfs_create_events_dir(const char *name, + struct dentry *parent, + struct rw_semaphore *eventfs_rwsem) +{ + struct dentry *dentry = tracefs_start_creating(name, parent); + struct eventfs_inode *ei; + struct tracefs_inode *ti; + struct inode *inode; + + if (IS_ERR(dentry)) + return dentry; + + ei = kzalloc(sizeof(*ei), GFP_KERNEL); + if (!ei) + return ERR_PTR(-ENOMEM); + inode = tracefs_get_inode(dentry->d_sb); + if (unlikely(!inode)) { + kfree(ei); + tracefs_failed_creating(dentry); + return ERR_PTR(-ENOMEM); + } + + init_rwsem(eventfs_rwsem); + INIT_LIST_HEAD(&ei->e_top_files); + + ti = get_tracefs(inode); + ti->flags |= TRACEFS_EVENT_INODE; + ti->private = ei; + + inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO; + inode->i_op = &eventfs_root_dir_inode_operations; + inode->i_fop = &eventfs_file_operations; + inode->i_private = eventfs_rwsem; + + /* directory inodes start off with i_nlink == 2 (for "." entry) */ + inc_nlink(inode); + d_instantiate(dentry, inode); + inc_nlink(dentry->d_parent->d_inode); + fsnotify_mkdir(dentry->d_parent->d_inode, dentry); + return tracefs_end_creating(dentry); +} + +/** + * eventfs_add_subsystem_dir - add eventfs subsystem_dir to list to create later + * @name: a pointer to a string containing the name of the file to create. + * @parent: a pointer to the parent dentry for this dir. + * @eventfs_rwsem: a pointer to rw_semaphore + * + * This function adds eventfs subsystem dir to list. + * And all these dirs are created on the fly when they are looked up, + * and the dentry and inodes will be removed when they are done. + */ +struct eventfs_file *eventfs_add_subsystem_dir(const char *name, + struct dentry *parent, + struct rw_semaphore *eventfs_rwsem) +{ + struct tracefs_inode *ti_parent; + struct eventfs_inode *ei_parent; + struct eventfs_file *ef; + + if (!parent) + return ERR_PTR(-EINVAL); + + ti_parent = get_tracefs(parent->d_inode); + ei_parent = ti_parent->private; + + ef = eventfs_prepare_ef(name, + S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO, + &eventfs_file_operations, + &eventfs_root_dir_inode_operations, + (void *) eventfs_rwsem); + + if (IS_ERR(ef)) + return ef; + + eventfs_down_write(eventfs_rwsem); + list_add_tail(&ef->list, &ei_parent->e_top_files); + ef->d_parent = parent; + eventfs_up_write(eventfs_rwsem); + return ef; +} + +/** + * eventfs_add_dir - add eventfs dir to list to create later + * @name: a pointer to a string containing the name of the file to create. + * @ef_parent: a pointer to the parent eventfs_file for this dir. + * @eventfs_rwsem: a pointer to rw_semaphore + * + * This function adds eventfs dir to list. + * And all these dirs are created on the fly when they are looked up, + * and the dentry and inodes will be removed when they are done. + */ +struct eventfs_file *eventfs_add_dir(const char *name, + struct eventfs_file *ef_parent, + struct rw_semaphore *eventfs_rwsem) +{ + struct eventfs_file *ef; + + if (!ef_parent) + return ERR_PTR(-EINVAL); + + ef = eventfs_prepare_ef(name, + S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO, + &eventfs_file_operations, + &eventfs_root_dir_inode_operations, + (void *) eventfs_rwsem); + + if (IS_ERR(ef)) + return ef; + + eventfs_down_write(eventfs_rwsem); + list_add_tail(&ef->list, &ef_parent->ei->e_top_files); + ef->d_parent = ef_parent->dentry; + eventfs_up_write(eventfs_rwsem); + return ef; +} diff --git a/include/linux/tracefs.h b/include/linux/tracefs.h index 999124459..aeca6761f 100644 --- a/include/linux/tracefs.h +++ b/include/linux/tracefs.h @@ -21,6 +21,35 @@ struct file_operations;

#ifdef CONFIG_TRACING

+struct eventfs_inode { + struct list_head e_top_files; +}; + +struct eventfs_file { + const char *name; + struct dentry *d_parent; + struct dentry *dentry; + struct list_head list; + struct eventfs_inode *ei; + const struct file_operations *fop; + const struct inode_operations *iop; + void *data; + umode_t mode; + bool created; +}; + +struct dentry *eventfs_create_events_dir(const char *name, + struct dentry *parent, + struct rw_semaphore *eventfs_rwsem); + +struct eventfs_file *eventfs_add_subsystem_dir(const char *name, + struct dentry *parent, + struct rw_semaphore *eventfs_rwsem); + +struct eventfs_file *eventfs_add_dir(const char *name, + struct eventfs_file *ef_parent, + struct rw_semaphore *eventfs_rwsem); + struct dentry *tracefs_create_file(const char *name, umode_t mode, struct dentry *parent, void *data, const struct file_operations *fops); diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 79bdefe92..b895c3346 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -359,6 +359,7 @@ struct trace_array { struct dentry *options; struct dentry *percpu_dir; struct dentry *event_dir; + struct rw_semaphore eventfs_rwsem; struct trace_options *topts; struct list_head systems; struct list_head events;

Adding following function to eventfs to add files:

eventfs_add_top_file() adds the information of top file to eventfs and dynamically creates these files as and when required.

eventfs_add_file() adds the information of nested files to eventfs and dynamically creates these dir as and when required.

Signed-off-by: Ajay Kaher akaher@vmware.com Co-developed-by: Steven Rostedt (VMware) rostedt@goodmis.org Signed-off-by: Steven Rostedt (VMware) rostedt@goodmis.org Tested-by: Ching-lin Yu chinglinyu@google.com Reported-by: kernel test robot lkp@intel.com Link: https://lore.kernel.org/oe-lkp/202305051619.9a469a9a-yujie.liu@intel.com --- fs/tracefs/event_inode.c | 94 ++++++++++++++++++++++++++++++++++++++++ include/linux/tracefs.h | 8 ++++ 2 files changed, 102 insertions(+)

diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c index a48ce23c0..17afb7476 100644 --- a/fs/tracefs/event_inode.c +++ b/fs/tracefs/event_inode.c @@ -270,3 +270,97 @@ struct eventfs_file *eventfs_add_dir(const char *name, eventfs_up_write(eventfs_rwsem); return ef; } + +/** + * eventfs_add_top_file - add event top file to list to create later + * @name: a pointer to a string containing the name of the file to create. + * @mode: the permission that the file should have. + * @parent: a pointer to the parent dentry for this file. This should be a + * directory dentry if set. If this parameter is NULL, then the + * file will be created in the root of the tracefs filesystem. + * @data: a pointer to something that the caller will want to get to later + * on. The inode.i_private pointer will point to this value on + * the open() call. + * @fop: a pointer to a struct file_operations that should be used for + * this file. + * + * This function adds top files of event dir to list. + * And all these files are created on the fly when they are looked up, + * and the dentry and inodes will be removed when they are done. + */ +int eventfs_add_top_file(const char *name, umode_t mode, + struct dentry *parent, void *data, + const struct file_operations *fop) +{ + struct tracefs_inode *ti; + struct eventfs_inode *ei; + struct eventfs_file *ef; + struct rw_semaphore *eventfs_rwsem; + + if (!parent) + return -EINVAL; + + if (!(mode & S_IFMT)) + mode |= S_IFREG; + + if (!parent->d_inode) + return -EINVAL; + + ti = get_tracefs(parent->d_inode); + if (!(ti->flags & TRACEFS_EVENT_INODE)) + return -EINVAL; + + ei = ti->private; + ef = eventfs_prepare_ef(name, mode, fop, NULL, data); + + if (IS_ERR(ef)) + return -ENOMEM; + + eventfs_rwsem = (struct rw_semaphore *) parent->d_inode->i_private; + eventfs_down_write(eventfs_rwsem); + list_add_tail(&ef->list, &ei->e_top_files); + ef->d_parent = parent; + eventfs_up_write(eventfs_rwsem); + return 0; +} + +/** + * eventfs_add_file - add eventfs file to list to create later + * @name: a pointer to a string containing the name of the file to create. + * @mode: the permission that the file should have. + * @ef_parent: a pointer to the parent eventfs_file for this file. + * @data: a pointer to something that the caller will want to get to later + * on. The inode.i_private pointer will point to this value on + * the open() call. + * @fop: a pointer to a struct file_operations that should be used for + * this file. + * + * This function adds top files of event dir to list. + * And all these files are created on the fly when they are looked up, + * and the dentry and inodes will be removed when they are done. + */ +int eventfs_add_file(const char *name, umode_t mode, + struct eventfs_file *ef_parent, + void *data, + const struct file_operations *fop) +{ + struct eventfs_file *ef; + struct rw_semaphore *eventfs_rwsem; + + if (!ef_parent) + return -EINVAL; + + if (!(mode & S_IFMT)) + mode |= S_IFREG; + + ef = eventfs_prepare_ef(name, mode, fop, NULL, data); + if (IS_ERR(ef)) + return -ENOMEM; + + eventfs_rwsem = (struct rw_semaphore *) ef_parent->data; + eventfs_down_write(eventfs_rwsem); + list_add_tail(&ef->list, &ef_parent->ei->e_top_files); + ef->d_parent = ef_parent->dentry; + eventfs_up_write(eventfs_rwsem); + return 0; +} diff --git a/include/linux/tracefs.h b/include/linux/tracefs.h index aeca6761f..1e1780a61 100644 --- a/include/linux/tracefs.h +++ b/include/linux/tracefs.h @@ -50,6 +50,14 @@ struct eventfs_file *eventfs_add_dir(const char *name, struct eventfs_file *ef_parent, struct rw_semaphore *eventfs_rwsem);

+int eventfs_add_file(const char *name, umode_t mode, + struct eventfs_file *ef_parent, void *data, + const struct file_operations *fops); + +int eventfs_add_top_file(const char *name, umode_t mode, + struct dentry *parent, void *data, + const struct file_operations *fops); + struct dentry *tracefs_create_file(const char *name, umode_t mode, struct dentry *parent, void *data, const struct file_operations *fops);

Adding eventfs_create_file(), eventfs_create_dir() to create file, dir at runtime as and when requires.

These function will be called either from lookup of inode_operations or open of file_operations.

Signed-off-by: Ajay Kaher akaher@vmware.com Co-developed-by: Steven Rostedt (VMware) rostedt@goodmis.org Signed-off-by: Steven Rostedt (VMware) rostedt@goodmis.org Tested-by: Ching-lin Yu chinglinyu@google.com --- fs/tracefs/event_inode.c | 125 +++++++++++++++++++++++++++++++++++++++ fs/tracefs/inode.c | 47 +++++++++++++++ include/linux/tracefs.h | 6 ++ 3 files changed, 178 insertions(+)

diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c index 874ef88bd..0ac1913cf 100644 --- a/fs/tracefs/event_inode.c +++ b/fs/tracefs/event_inode.c @@ -83,6 +83,131 @@ static void eventfs_up_write(struct rw_semaphore *eventfs_rwsem) up_write(eventfs_rwsem); }

+/** + * eventfs_create_file - create a file in the tracefs filesystem + * @name: a pointer to a string containing the name of the file to create. + * @mode: the permission that the file should have. + * @parent: a pointer to the parent dentry for this file. This should be a + * directory dentry if set. If this parameter is NULL, then the + * file will be created in the root of the tracefs filesystem. + * @data: a pointer to something that the caller will want to get to later + * on. The inode.i_private pointer will point to this value on + * the open() call. + * @fop: a pointer to a struct file_operations that should be used for + * this file. + * + * This is the basic "create a file" function for tracefs. It allows for a + * wide range of flexibility in creating a file. + * + * This function will return a pointer to a dentry if it succeeds. This + * pointer must be passed to the tracefs_remove() function when the file is + * to be removed (no automatic cleanup happens if your module is unloaded, + * you are responsible here.) If an error occurs, %NULL will be returned. + * + * If tracefs is not enabled in the kernel, the value -%ENODEV will be + * returned. + */ +static struct dentry *eventfs_create_file(const char *name, umode_t mode, + struct dentry *parent, void *data, + const struct file_operations *fop) +{ + struct tracefs_inode *ti; + struct dentry *dentry; + struct inode *inode; + + if (security_locked_down(LOCKDOWN_TRACEFS)) + return NULL; + + if (!(mode & S_IFMT)) + mode |= S_IFREG; + + if (WARN_ON_ONCE(!S_ISREG(mode))) + return NULL; + + dentry = eventfs_start_creating(name, parent); + + if (IS_ERR(dentry)) + return dentry; + + inode = tracefs_get_inode(dentry->d_sb); + if (unlikely(!inode)) + return eventfs_failed_creating(dentry); + + inode->i_mode = mode; + inode->i_fop = fop; + inode->i_private = data; + + 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); +} + +/** + * eventfs_create_dir - create a dir in the tracefs filesystem + * @name: a pointer to a string containing the name of the file to create. + * @mode: the permission that the file should have. + * @parent: a pointer to the parent dentry for this file. This should be a + * directory dentry if set. If this parameter is NULL, then the + * file will be created in the root of the tracefs filesystem. + * @data: a pointer to something that the caller will want to get to later + * on. The inode.i_private pointer will point to this value on + * the open() call. + * @fop: a pointer to a struct file_operations that should be used for + * this dir. + * @iop: a pointer to a struct inode_operations that should be used for + * this dir. + * + * This is the basic "create a dir" function for eventfs. It allows for a + * wide range of flexibility in creating a dir. + * + * This function will return a pointer to a dentry if it succeeds. This + * pointer must be passed to the tracefs_remove() function when the file is + * to be removed (no automatic cleanup happens if your module is unloaded, + * you are responsible here.) If an error occurs, %NULL will be returned. + * + * If tracefs is not enabled in the kernel, the value -%ENODEV will be + * returned. + */ +static struct dentry *eventfs_create_dir(const char *name, umode_t mode, + struct dentry *parent, void *data, + const struct file_operations *fop, + const struct inode_operations *iop) +{ + struct tracefs_inode *ti; + struct dentry *dentry; + struct inode *inode; + + if (security_locked_down(LOCKDOWN_TRACEFS)) + return NULL; + + WARN_ON(!S_ISDIR(mode)); + + dentry = eventfs_start_creating(name, parent); + + if (IS_ERR(dentry)) + return dentry; + + inode = tracefs_get_inode(dentry->d_sb); + if (unlikely(!inode)) + return eventfs_failed_creating(dentry); + + inode->i_mode = mode; + inode->i_op = iop; + inode->i_fop = fop; + inode->i_private = data; + + ti = get_tracefs(inode); + ti->flags |= TRACEFS_EVENT_INODE; + + 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); +} + static const struct file_operations eventfs_file_operations = { };

diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c index 7df1752e8..66c4df734 100644 --- a/fs/tracefs/inode.c +++ b/fs/tracefs/inode.c @@ -452,6 +452,53 @@ struct dentry *tracefs_end_creating(struct dentry *dentry) return dentry; }

+struct dentry *eventfs_start_creating(const char *name, struct dentry *parent) +{ + struct dentry *dentry; + int error; + + error = simple_pin_fs(&trace_fs_type, &tracefs_mount, + &tracefs_mount_count); + if (error) + return ERR_PTR(error); + + /* + * If the parent is not specified, we create it in the root. + * We need the root dentry to do this, which is in the super + * block. A pointer to that is in the struct vfsmount that we + * have around. + */ + if (!parent) + parent = tracefs_mount->mnt_root; + + 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; +} + +struct dentry *eventfs_failed_creating(struct dentry *dentry) +{ + dput(dentry); + simple_release_fs(&tracefs_mount, &tracefs_mount_count); + return NULL; +} + +struct dentry *eventfs_end_creating(struct dentry *dentry) +{ + return dentry; +} + /** * tracefs_create_file - create a file in the tracefs filesystem * @name: a pointer to a string containing the name of the file to create. diff --git a/include/linux/tracefs.h b/include/linux/tracefs.h index ea10ccc87..57bfd1322 100644 --- a/include/linux/tracefs.h +++ b/include/linux/tracefs.h @@ -38,6 +38,12 @@ struct eventfs_file { bool created; };

+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); + struct dentry *eventfs_create_events_dir(const char *name, struct dentry *parent, struct rw_semaphore *eventfs_rwsem);

Creating tracefs_inode_cache which is a cache of tracefs_inode. Adding helping functions: tracefs_alloc_inode() tracefs_free_inode()

Signed-off-by: Ajay Kaher akaher@vmware.com Co-developed-by: Steven Rostedt (VMware) rostedt@goodmis.org Signed-off-by: Steven Rostedt (VMware) rostedt@goodmis.org Tested-by: Ching-lin Yu chinglinyu@google.com --- fs/tracefs/inode.c | 38 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 38 insertions(+)

diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c index 66c4df734..76820d3e9 100644 --- a/fs/tracefs/inode.c +++ b/fs/tracefs/inode.c @@ -24,11 +24,30 @@ #include "internal.h"

#define TRACEFS_DEFAULT_MODE 0700 +static struct kmem_cache *tracefs_inode_cachep __ro_after_init;

static struct vfsmount *tracefs_mount; static int tracefs_mount_count; static bool tracefs_registered;

+static struct inode *tracefs_alloc_inode(struct super_block *sb) +{ + struct tracefs_inode *ti; + + ti = kmem_cache_alloc(tracefs_inode_cachep, GFP_KERNEL); + if (!ti) + return NULL; + + ti->flags = 0; + + return &ti->vfs_inode; +} + +static void tracefs_free_inode(struct inode *inode) +{ + kmem_cache_free(tracefs_inode_cachep, get_tracefs(inode)); +} + static ssize_t default_read_file(struct file *file, char __user *buf, size_t count, loff_t *ppos) { @@ -347,6 +366,9 @@ static int tracefs_show_options(struct seq_file *m, struct dentry *root) }

static const struct super_operations tracefs_super_operations = { + .alloc_inode = tracefs_alloc_inode, + .free_inode = tracefs_free_inode, + .drop_inode = generic_delete_inode, .statfs = simple_statfs, .remount_fs = tracefs_remount, .show_options = tracefs_show_options, @@ -676,10 +698,26 @@ bool tracefs_initialized(void) return tracefs_registered; }

+static void init_once(void *foo) +{ + struct tracefs_inode *ti = (struct tracefs_inode *) foo; + + inode_init_once(&ti->vfs_inode); +} + static int __init tracefs_init(void) { int retval;

+ tracefs_inode_cachep = kmem_cache_create("tracefs_inode_cache", + sizeof(struct tracefs_inode), + 0, (SLAB_RECLAIM_ACCOUNT| + SLAB_MEM_SPREAD| + SLAB_ACCOUNT), + init_once); + if (!tracefs_inode_cachep) + return -ENOMEM; + retval = sysfs_create_mount_point(kernel_kobj, "tracing"); if (retval) return -EINVAL;

kprobe_args_char.tc, kprobe_args_string.tc has validation check for tracefs_create_dir, for eventfs it should be eventfs_create_dir.

Signed-off-by: Ajay Kaher akaher@vmware.com Co-developed-by: Steven Rostedt (VMware) rostedt@goodmis.org Signed-off-by: Steven Rostedt (VMware) rostedt@goodmis.org Tested-by: Ching-lin Yu chinglinyu@google.com --- .../selftests/ftrace/test.d/kprobe/kprobe_args_char.tc | 4 ++-- .../selftests/ftrace/test.d/kprobe/kprobe_args_string.tc | 4 ++-- 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_args_char.tc b/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_args_char.tc index 285b4770e..523cfb645 100644 --- a/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_args_char.tc +++ b/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_args_char.tc @@ -34,14 +34,14 @@ mips*) esac

: "Test get argument (1)" -echo "p:testprobe tracefs_create_dir arg1=+0(${ARG1}):char" > kprobe_events +echo "p:testprobe eventfs_add_dir arg1=+0(${ARG1}):char" > kprobe_events echo 1 > events/kprobes/testprobe/enable echo "p:test $FUNCTION_FORK" >> kprobe_events grep -qe "testprobe.* arg1='t'" trace

echo 0 > events/kprobes/testprobe/enable : "Test get argument (2)" -echo "p:testprobe tracefs_create_dir arg1=+0(${ARG1}):char arg2=+0(${ARG1}):char[4]" > kprobe_events +echo "p:testprobe eventfs_add_dir arg1=+0(${ARG1}):char arg2=+0(${ARG1}):char[4]" > kprobe_events echo 1 > events/kprobes/testprobe/enable echo "p:test $FUNCTION_FORK" >> kprobe_events grep -qe "testprobe.* arg1='t' arg2={'t','e','s','t'}" trace diff --git a/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_args_string.tc b/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_args_string.tc index a4f8e7c53..b9f8c3f8b 100644 --- a/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_args_string.tc +++ b/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_args_string.tc @@ -37,14 +37,14 @@ loongarch*) esac

: "Test get argument (1)" -echo "p:testprobe tracefs_create_dir arg1=+0(${ARG1}):string" > kprobe_events +echo "p:testprobe eventfs_add_dir arg1=+0(${ARG1}):string" > kprobe_events echo 1 > events/kprobes/testprobe/enable echo "p:test $FUNCTION_FORK" >> kprobe_events grep -qe "testprobe.* arg1="test"" trace

echo 0 > events/kprobes/testprobe/enable : "Test get argument (2)" -echo "p:testprobe tracefs_create_dir arg1=+0(${ARG1}):string arg2=+0(${ARG1}):string" > kprobe_events +echo "p:testprobe eventfs_add_dir arg1=+0(${ARG1}):string arg2=+0(${ARG1}):string" > kprobe_events echo 1 > events/kprobes/testprobe/enable echo "p:test $FUNCTION_FORK" >> kprobe_events grep -qe "testprobe.* arg1="test" arg2="test"" trace