Cleanup regex_lock and ftrace_lock locking points around
ftrace_ops hash update code.
The new rule is that regex_lock protects ops->*_hash
read-update-write code for each ftrace_ops. Usually,
hash update is done by following sequence.
1. allocate a new local hash and copy the original hash.
2. update the local hash.
3. move(actually, copy) back the local hash to ftrace_ops.
4. update ftrace entries if needed.
5. release the local hash.
This makes regex_lock to protect #1-#4, and ftrace_lock
to protect #3 and #4.
Signed-off-by: Masami Hiramatsu <masami.hiramatsu...@hitachi.com>
Cc: Steven Rostedt <rost...@goodmis.org>
Cc: Frederic Weisbecker <fweis...@gmail.com>
Cc: Ingo Molnar <mi...@redhat.com>
Cc: Tom Zanussi <tom.zanu...@intel.com>
---
kernel/trace/ftrace.c | 59 +++++++++++++++++++++++++++----------------------
1 file changed, 32 insertions(+), 27 deletions(-)
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 3f29b3d..0575b3f 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -2644,28 +2644,26 @@ ftrace_regex_open(struct ftrace_ops *ops, int flag,
return -ENOMEM;
}
+ iter->ops = ops;
+ iter->flags = flag;
+
+ mutex_lock(&ops->regex_lock);
+
if (flag & FTRACE_ITER_NOTRACE)
hash = ops->notrace_hash;
else
hash = ops->filter_hash;
- iter->ops = ops;
- iter->flags = flag;
-
if (file->f_mode & FMODE_WRITE) {
- mutex_lock(&ftrace_lock);
iter->hash =
alloc_and_copy_ftrace_hash(FTRACE_HASH_DEFAULT_BITS, hash);
- mutex_unlock(&ftrace_lock);
-
if (!iter->hash) {
trace_parser_put(&iter->parser);
kfree(iter);
- return -ENOMEM;
+ ret = -ENOMEM;
+ goto out_unlock;
}
}
- mutex_lock(&ops->regex_lock);
-
if ((file->f_mode & FMODE_WRITE) &&
(file->f_flags & O_TRUNC))
ftrace_filter_reset(iter->hash);
@@ -2685,6 +2683,8 @@ ftrace_regex_open(struct ftrace_ops *ops, int flag,
}
} else
file->private_data = iter;
+
+ out_unlock:
mutex_unlock(&ops->regex_lock);
return ret;
@@ -2999,7 +2999,7 @@ register_ftrace_function_probe(char *glob, struct
ftrace_probe_ops *ops,
if (WARN_ON(not))
return -EINVAL;
- mutex_lock(&ftrace_lock);
+ mutex_lock(&trace_probe_ops.regex_lock);
hash = alloc_and_copy_ftrace_hash(FTRACE_HASH_DEFAULT_BITS, *orig_hash);
if (!hash) {
@@ -3057,14 +3057,16 @@ register_ftrace_function_probe(char *glob, struct
ftrace_probe_ops *ops,
} while_for_each_ftrace_rec();
+ mutex_lock(&ftrace_lock);
ret = ftrace_hash_move(&trace_probe_ops, 1, orig_hash, hash);
if (ret < 0)
count = ret;
__enable_ftrace_function_probe();
+ mutex_unlock(&ftrace_lock);
out_unlock:
- mutex_unlock(&ftrace_lock);
+ mutex_unlock(&trace_probe_ops.regex_lock);
free_ftrace_hash(hash);
return count;
@@ -3104,7 +3106,7 @@ __unregister_ftrace_function_probe(char *glob, struct
ftrace_probe_ops *ops,
return;
}
- mutex_lock(&ftrace_lock);
+ mutex_lock(&trace_probe_ops.regex_lock);
hash = alloc_and_copy_ftrace_hash(FTRACE_HASH_DEFAULT_BITS, *orig_hash);
if (!hash)
@@ -3142,6 +3144,7 @@ __unregister_ftrace_function_probe(char *glob, struct
ftrace_probe_ops *ops,
list_add(&entry->free_list, &free_list);
}
}
+ mutex_lock(&ftrace_lock);
__disable_ftrace_function_probe();
/*
* Remove after the disable is called. Otherwise, if the last
@@ -3153,9 +3156,10 @@ __unregister_ftrace_function_probe(char *glob, struct
ftrace_probe_ops *ops,
list_del(&entry->free_list);
ftrace_free_entry(entry);
}
+ mutex_unlock(&ftrace_lock);
out_unlock:
- mutex_unlock(&ftrace_lock);
+ mutex_unlock(&trace_probe_ops.regex_lock);
free_ftrace_hash(hash);
}
@@ -3271,11 +3275,10 @@ ftrace_regex_write(struct file *file, const char __user
*ubuf,
} else
iter = file->private_data;
- mutex_lock(&iter->ops->regex_lock);
-
- ret = -ENODEV;
if (unlikely(ftrace_disabled))
- goto out_unlock;
+ return -ENODEV;
+
+ /* iter->hash is a local copy, so we don't need regex_lock */
parser = &iter->parser;
read = trace_get_user(parser, ubuf, cnt, ppos);
@@ -3286,13 +3289,11 @@ ftrace_regex_write(struct file *file, const char __user
*ubuf,
parser->idx, enable);
trace_parser_clear(parser);
if (ret)
- goto out_unlock;
+ goto out;
}
ret = read;
-out_unlock:
- mutex_unlock(&iter->ops->regex_lock);
-
+ out:
return ret;
}
@@ -3344,16 +3345,19 @@ ftrace_set_hash(struct ftrace_ops *ops, unsigned char
*buf, int len,
if (unlikely(ftrace_disabled))
return -ENODEV;
+ mutex_lock(&ops->regex_lock);
+
if (enable)
orig_hash = &ops->filter_hash;
else
orig_hash = &ops->notrace_hash;
hash = alloc_and_copy_ftrace_hash(FTRACE_HASH_DEFAULT_BITS, *orig_hash);
- if (!hash)
- return -ENOMEM;
+ if (!hash) {
+ ret = -ENOMEM;
+ goto out_regex_unlock;
+ }
- mutex_lock(&ops->regex_lock);
if (reset)
ftrace_filter_reset(hash);
if (buf && !ftrace_match_records(hash, buf, len)) {
@@ -3566,8 +3570,6 @@ int ftrace_regex_release(struct inode *inode, struct file
*file)
} else
iter = file->private_data;
- mutex_lock(&iter->ops->regex_lock);
-
parser = &iter->parser;
if (trace_parser_loaded(parser)) {
parser->buffer[parser->idx] = 0;
@@ -3576,6 +3578,8 @@ int ftrace_regex_release(struct inode *inode, struct file
*file)
trace_parser_put(parser);
+ mutex_lock(&iter->ops->regex_lock);
+
if (file->f_mode & FMODE_WRITE) {
filter_hash = !!(iter->flags & FTRACE_ITER_FILTER);
@@ -3593,10 +3597,11 @@ int ftrace_regex_release(struct inode *inode, struct
file *file)
mutex_unlock(&ftrace_lock);
}
+
+ mutex_unlock(&iter->ops->regex_lock);
free_ftrace_hash(iter->hash);
kfree(iter);
- mutex_unlock(&iter->ops->regex_lock);
return 0;
}
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