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authorOleg Nesterov <oleg@redhat.com>2013-07-28 20:35:27 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-08-29 09:47:34 -0700
commit012dc156d6af49e02a30fcba7d688e251608d97c (patch)
tree9df8015705569ced239b24ae56872eabc2b15054
parentc6febdf258313a120acd1298dd1dd41442131a37 (diff)
tracing: Change remove_event_file_dir() to clear "d_subdirs"->i_private
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@redhat.com Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--kernel/trace/trace_events.c47
1 files changed, 15 insertions, 32 deletions
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 422f99dfe699..0bff8aaf581b 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -426,42 +426,26 @@ static void *event_file_data(struct file *filp)
static void remove_event_file_dir(struct ftrace_event_file *file)
{
+ struct dentry *dir = file->dir;
+ struct dentry *child;
+
+ 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);
+
+ debugfs_remove_recursive(dir);
+ }
+
list_del(&file->list);
- debugfs_remove_recursive(file->dir);
remove_subsystem(file->system);
kmem_cache_free(file_cachep, file);
}
/*
- * 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;
-
- trace_array_put(tr);
-
- return 0;
-}
-
-/*
* __ftrace_set_clr_event(NULL, NULL, NULL, set) will set/unset all events.
*/
static int
@@ -1303,10 +1287,9 @@ static const struct file_operations ftrace_set_event_fops = {
};
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,
};