From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752147Ab3EIFrF (ORCPT ); Thu, 9 May 2013 01:47:05 -0400 Received: from mail7.hitachi.co.jp ([133.145.228.42]:42651 "EHLO mail7.hitachi.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751814Ab3EIFrB (ORCPT ); Thu, 9 May 2013 01:47:01 -0400 X-AuditID: 85900ec0-d56cbb900000151e-8c-518b38520aff Subject: [PATCH 03/11] ftrace: Cleanup regex_lock and ftrace_lock around hash updating To: linux-kernel@vger.kernel.org, Steven Rostedt From: Masami Hiramatsu Cc: Srikar Dronamraju , Frederic Weisbecker , yrl.pp-manager.tt@hitachi.com, Oleg Nesterov , Ingo Molnar , Tom Zanussi Date: Thu, 09 May 2013 14:44:21 +0900 Message-ID: <20130509054421.30398.83411.stgit@mhiramat-M0-7522> In-Reply-To: <20130509054405.30398.73831.stgit@mhiramat-M0-7522> References: <20130509054405.30398.73831.stgit@mhiramat-M0-7522> User-Agent: StGit/0.15 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Brightmail-Tracker: AAAAAA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 Cc: Steven Rostedt Cc: Frederic Weisbecker Cc: Ingo Molnar Cc: Tom Zanussi --- 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; }