Commit 704f960d authored by Steven Rostedt (Google)'s avatar Steven Rostedt (Google)
Browse files

eventfs: Read ei->entries before ei->children in eventfs_iterate() 

In order to apply a shortcut to skip over the current ctx->pos
immediately, by using the ei->entries array, the reading of that array
should be first. Moving the array reading before the linked list reading
will make the shortcut change diff nicer to read.

Link: https://lore.kernel.org/all/CAHk-=wiKwDUDv3+jCsv-uacDcHDVTYsXtBR9=6sGM5mqX+DhOg@mail.gmail.com/
Link: https://lore.kernel.org/linux-trace-kernel/20240104220048.333115095@goodmis.org



Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent 1e4624eb

fs/tracefs/event_inode.c

+23 −23
Original line number Diff line number Diff line
@@ -752,8 +752,8 @@ static int eventfs_iterate(struct file *file, struct dir_context *ctx) 
	 * Need to create the dentries and inodes to have a consistent

	 * inode number.

	 */

	list_for_each_entry_srcu(ei_child, &ei->children, list,

				 srcu_read_lock_held(&eventfs_srcu)) {

	for (i = 0; i < ei->nr_entries; i++) {

		void *cdata = ei->data;



		if (c > 0) {

			c--;
@@ -762,23 +762,32 @@ static int eventfs_iterate(struct file *file, struct dir_context *ctx) 


		ctx->pos++;



		if (ei_child->is_freed)

			continue;

		entry = &ei->entries[i];

		name = entry->name;



		name = ei_child->name;

		mutex_lock(&eventfs_mutex);

		/* If ei->is_freed then just bail here, nothing more to do */

		if (ei->is_freed) {

			mutex_unlock(&eventfs_mutex);

			goto out_dec;

		}

		r = entry->callback(name, &mode, &cdata, &fops);

		mutex_unlock(&eventfs_mutex);

		if (r <= 0)

			continue;



		dentry = create_dir_dentry(ei, ei_child, ei_dentry);

		dentry = create_file_dentry(ei, i, ei_dentry, name, mode, cdata, fops);

		if (!dentry)

			goto out_dec;

		ino = dentry->d_inode->i_ino;

		dput(dentry);



		if (!dir_emit(ctx, name, strlen(name), ino, DT_DIR))

		if (!dir_emit(ctx, name, strlen(name), ino, DT_REG))

			goto out_dec;

	}



	for (i = 0; i < ei->nr_entries; i++) {

		void *cdata = ei->data;

	list_for_each_entry_srcu(ei_child, &ei->children, list,

				 srcu_read_lock_held(&eventfs_srcu)) {



		if (c > 0) {

			c--;
@@ -787,27 +796,18 @@ static int eventfs_iterate(struct file *file, struct dir_context *ctx) 


		ctx->pos++;



		entry = &ei->entries[i];

		name = entry->name;



		mutex_lock(&eventfs_mutex);

		/* If ei->is_freed then just bail here, nothing more to do */

		if (ei->is_freed) {

			mutex_unlock(&eventfs_mutex);

			goto out_dec;

		}

		r = entry->callback(name, &mode, &cdata, &fops);

		mutex_unlock(&eventfs_mutex);

		if (r <= 0)

		if (ei_child->is_freed)

			continue;



		dentry = create_file_dentry(ei, i, ei_dentry, name, mode, cdata, fops);

		name = ei_child->name;



		dentry = create_dir_dentry(ei, ei_child, ei_dentry);

		if (!dentry)

			goto out_dec;

		ino = dentry->d_inode->i_ino;

		dput(dentry);



		if (!dir_emit(ctx, name, strlen(name), ino, DT_REG))

		if (!dir_emit(ctx, name, strlen(name), ino, DT_DIR))

			goto out_dec;

	}

	ret = 1;