From: Steven Rostedt <rostedt@goodmis.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>,
linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org
Subject: Re: [PATCH 5/6] eventfs: get rid of dentry pointers without refcounts
Date: Tue, 30 Jan 2024 15:55:50 -0500 [thread overview]
Message-ID: <20240130155550.4881d558@gandalf.local.home> (raw)
In-Reply-To: <20240130190355.11486-5-torvalds@linux-foundation.org>
On Tue, 30 Jan 2024 11:03:54 -0800
Linus Torvalds <torvalds@linux-foundation.org> wrote:
> -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);
> + int namesize = strlen(name) + 1;
> + struct eventfs_inode *ei = kzalloc(sizeof(*ei) + namesize, GFP_KERNEL);
> +
> + if (ei) {
> + memcpy((char *)ei->name, name, namesize);
> + kref_init(&ei->kref);
> + }
I'm going to be putting back the ei->name pointer as the above actually
adds more memory usage. The reason being is that all static trace events
(not kprobes or other dynamic events) are created with the TRACE_EVENT()
macro that points to a constant name. Passing in a const to kstrdup_const()
checks if the name passed in is a constant or not. If it is, it doesn't
allocate the name and just passes back the pointer.
Removing the pointer to "name" removed 8 bytes on 64 bit machines from the
eventfs_inode structure, but added strlen(name)+1 bytes to it, where the
majority of trace event names are greater than 8 bytes, and are constant
strings.
Another reason for converting back to the way it was is I have moving the
ei allocation to a slab on my TODO list.
-- Steve
> + return ei;
> }
>
> diff --git a/fs/tracefs/internal.h b/fs/tracefs/internal.h
> index 8f38740bfb5b..72db3bdc4dfb 100644
> --- a/fs/tracefs/internal.h
> +++ b/fs/tracefs/internal.h
> @@ -34,8 +34,7 @@ struct eventfs_attr {
> * @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_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
> @@ -44,12 +43,11 @@ struct eventfs_attr {
> * @nr_entries: The number of items in @entries
> */
> struct eventfs_inode {
> + struct kref kref;
> struct list_head list;
> const struct eventfs_entry *entries;
> - const char *name;
> struct list_head children;
> - struct dentry *dentry; /* Check is_freed to access */
> - struct dentry **d_children;
> + struct dentry *events_dir;
> struct eventfs_attr *entry_attrs;
> struct eventfs_attr attr;
> void *data;
> @@ -66,6 +64,7 @@ struct eventfs_inode {
> struct llist_node llist;
> struct rcu_head rcu;
> };
> + const char name[];
> };
>
> static inline struct tracefs_inode *get_tracefs(const struct inode *inode)
next prev parent reply other threads:[~2024-01-30 20:55 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-30 19:03 [PATCH 1/6] tracefs: avoid using the ei->dentry pointer unnecessarily Linus Torvalds
2024-01-30 19:03 ` [PATCH 2/6] eventfsfs: initialize the tracefs inode properly Linus Torvalds
2024-01-30 19:48 ` Steven Rostedt
2024-01-30 19:56 ` Steven Rostedt
2024-01-30 19:49 ` Steven Rostedt
2024-01-30 19:03 ` [PATCH 3/6] tracefs: dentry lookup crapectomy Linus Torvalds
2024-01-30 23:26 ` Al Viro
2024-01-30 23:55 ` Steven Rostedt
2024-01-31 0:07 ` Al Viro
2024-01-31 0:23 ` Al Viro
2024-01-31 0:39 ` Linus Torvalds
2024-01-30 19:03 ` [PATCH 4/6] eventfs: remove unused 'd_parent' pointer field Linus Torvalds
2024-01-30 19:03 ` [PATCH 5/6] eventfs: get rid of dentry pointers without refcounts Linus Torvalds
2024-01-30 20:55 ` Steven Rostedt [this message]
2024-01-30 21:52 ` Linus Torvalds
2024-01-30 22:56 ` Steven Rostedt
2024-01-30 22:58 ` Linus Torvalds
2024-01-30 23:04 ` Steven Rostedt
2024-01-30 22:56 ` Linus Torvalds
2024-01-30 23:06 ` Linus Torvalds
2024-01-30 23:10 ` Steven Rostedt
2024-01-30 23:25 ` Linus Torvalds
2024-01-31 0:48 ` Al Viro
2024-01-31 5:09 ` Steven Rostedt
2024-01-31 5:25 ` Linus Torvalds
2024-01-31 5:33 ` Steven Rostedt
2024-01-31 5:57 ` Linus Torvalds
2024-01-31 6:20 ` Linus Torvalds
2024-01-31 12:57 ` Steven Rostedt
2024-01-31 13:14 ` Steven Rostedt
2024-01-31 18:08 ` Linus Torvalds
2024-01-31 18:39 ` Steven Rostedt
2024-01-30 19:03 ` [PATCH 6/6] eventfs: clean up dentry ops and add revalidate function Linus Torvalds
2024-01-30 21:25 ` Steven Rostedt
2024-01-30 21:36 ` Linus Torvalds
2024-01-31 1:12 ` Al Viro
2024-01-31 2:37 ` Linus Torvalds
2024-01-31 2:46 ` Al Viro
2024-01-31 3:39 ` Linus Torvalds
2024-01-31 4:28 ` Al Viro
2024-01-31 18:00 ` Steven Rostedt
2024-01-31 23:07 ` Masami Hiramatsu
2024-01-31 23:23 ` Steven Rostedt
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