This is a note to let you know that I've just added the patch titled
tracing: Change remove_event_file_dir() to clear "d_subdirs"->i_private
to the 3.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
tracing-change-remove_event_file_dir-to-clear-d_subdirs-i_private.patch
and it can be found in the queue-3.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From bf682c3159c4d298d1126a56793ed3f5e80395f7 Mon Sep 17 00:00:00 2001
From: Oleg Nesterov <oleg@xxxxxxxxxx>
Date: Sun, 28 Jul 2013 20:35:27 +0200
Subject: tracing: Change remove_event_file_dir() to clear "d_subdirs"->i_private
From: Oleg Nesterov <oleg@xxxxxxxxxx>
commit bf682c3159c4d298d1126a56793ed3f5e80395f7 upstream.
Change remove_event_file_dir() to clear ->i_private for every
file we are going to remove.
We need to check file->dir != NULL because event_create_dir()
can fail. debugfs_remove_recursive(NULL) is fine but the patch
moves it under the same check anyway for readability.
spin_lock(d_lock) and "d_inode != NULL" check are not needed
afaics, but I do not understand this code enough.
tracing_open_generic_file() and tracing_release_generic_file()
can go away, ftrace_enable_fops and ftrace_event_filter_fops()
use tracing_open_generic() but only to check tracing_disabled.
This fixes all races with event_remove() or instance_delete().
f_op->read/write/whatever can never use the freed file/call,
all event/* files were changed to check and use ->i_private
under event_mutex.
Note: this doesn't not fix other problems, event_remove() can
destroy the active ftrace_event_call, we need more changes but
those changes are completely orthogonal.
Link: http://lkml.kernel.org/r/20130728183527.GB16723@xxxxxxxxxx
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/trace/trace_events.c | 47 ++++++++++++++------------------------------
1 file changed, 15 insertions(+), 32 deletions(-)
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -426,39 +426,23 @@ static void *event_file_data(struct file
static void remove_event_file_dir(struct ftrace_event_file *file)
{
- list_del(&file->list);
- debugfs_remove_recursive(file->dir);
- remove_subsystem(file->system);
- kmem_cache_free(file_cachep, file);
-}
+ struct dentry *dir = file->dir;
+ struct dentry *child;
-/*
- * Open and update trace_array ref count.
- * Must have the current trace_array passed to it.
- */
-static int tracing_open_generic_file(struct inode *inode, struct file *filp)
-{
- struct ftrace_event_file *file = inode->i_private;
- struct trace_array *tr = file->tr;
- int ret;
-
- if (trace_array_get(tr) < 0)
- return -ENODEV;
-
- ret = tracing_open_generic(inode, filp);
- if (ret < 0)
- trace_array_put(tr);
- return ret;
-}
-
-static int tracing_release_generic_file(struct inode *inode, struct file *filp)
-{
- struct ftrace_event_file *file = inode->i_private;
- struct trace_array *tr = file->tr;
+ if (dir) {
+ spin_lock(&dir->d_lock); /* probably unneeded */
+ list_for_each_entry(child, &dir->d_subdirs, d_u.d_child) {
+ if (child->d_inode) /* probably unneeded */
+ child->d_inode->i_private = NULL;
+ }
+ spin_unlock(&dir->d_lock);
- trace_array_put(tr);
+ debugfs_remove_recursive(dir);
+ }
- return 0;
+ list_del(&file->list);
+ remove_subsystem(file->system);
+ kmem_cache_free(file_cachep, file);
}
/*
@@ -1303,10 +1287,9 @@ static const struct file_operations ftra
};
static const struct file_operations ftrace_enable_fops = {
- .open = tracing_open_generic_file,
+ .open = tracing_open_generic,
.read = event_enable_read,
.write = event_enable_write,
- .release = tracing_release_generic_file,
.llseek = default_llseek,
};
Patches currently in stable-queue which might be from oleg@xxxxxxxxxx are
queue-3.10/tracing-introduce-trace_create_cpu_file-and.patch
queue-3.10/tracing-introduce-remove_event_file_dir.patch
queue-3.10/tracing-change-event_filter_read-write-to-verify-i_private-null.patch
queue-3.10/tracing-change-remove_event_file_dir-to-clear-d_subdirs-i_private.patch
queue-3.10/tracing-change-tracing_fops-snapshot_fops-to-rely-on-tracing_get_cpu.patch
queue-3.10/tracing-change-tracing_buffers_fops-to-rely-on-tracing_get_cpu.patch
queue-3.10/tracing-change-f_start-to-take-event_mutex-and-verify-i_private-null.patch
queue-3.10/tracing-change-event_enable-disable_read-to-verify-i_private-null.patch
queue-3.10/tracing-change-tracing_stats_fops-to-rely-on.patch
queue-3.10/tracing-change-tracing_pipe_fops-to-rely-on-tracing_get_cpu.patch
queue-3.10/tracing-change-tracing_entries_fops-to-rely-on-tracing_get_cpu.patch
queue-3.10/tracing-turn-event-id-i_private-into-call-event.type.patch
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