Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753852Ab3GXUIE (ORCPT ); Wed, 24 Jul 2013 16:08:04 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122]:21290 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753029Ab3GXUIC (ORCPT ); Wed, 24 Jul 2013 16:08:02 -0400 X-Authority-Analysis: v=2.0 cv=e9yEuNV/ c=1 sm=0 a=Sro2XwOs0tJUSHxCKfOySw==:17 a=Drc5e87SC40A:10 a=wtjnJb8W-_0A:10 a=5SG0PmZfjMsA:10 a=IkcTkHD0fZMA:10 a=meVymXHHAAAA:8 a=KGjhK52YXX0A:10 a=EnbaTta9GQwA:10 a=20KFwNOVAAAA:8 a=mo9_zJyWI30ozzNMY1EA:9 a=QEXdDO2ut3YA:10 a=jEp0ucaQiEUA:10 a=Sro2XwOs0tJUSHxCKfOySw==:117 X-Cloudmark-Score: 0 X-Authenticated-User: X-Originating-IP: 67.255.60.225 Message-ID: <1374696480.3356.158.camel@gandalf.local.home> Subject: Re: [PATCH 6/6] tracing: Change remove_event_file_dir() to clear "d_subdirs"->i_private From: Steven Rostedt To: Oleg Nesterov Cc: Masami Hiramatsu , Alexander Z Lam , Arnaldo Carvalho de Melo , David Sharp , Frederic Weisbecker , Ingo Molnar , Peter Zijlstra , Srikar Dronamraju , Vaibhav Nagarnaik , "zhangwei(Jovi)" , linux-kernel@vger.kernel.org Date: Wed, 24 Jul 2013 16:08:00 -0400 In-Reply-To: <20130723205927.GA9082@redhat.com> References: <20130723205927.GA9082@redhat.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.4.4-3 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3256 Lines: 107 On Tue, 2013-07-23 at 22:59 +0200, Oleg Nesterov wrote: > Change remove_event_file_dir() ->i_private for every file we > are going to remove. > > 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. Hmm, but this patch opens up that race right? We remove the tr ref counter updates here. > > Signed-off-by: Oleg Nesterov > --- > kernel/trace/trace_events.c | 40 ++++++++-------------------------------- > 1 files changed, 8 insertions(+), 32 deletions(-) > > diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c > index 3ae037c..298e4fa 100644 > --- a/kernel/trace/trace_events.c > +++ b/kernel/trace/trace_events.c > @@ -428,42 +428,19 @@ 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; Need space here. > + /* ->i_mutex is not needed, nodody can create/remove a file */ "nodody" ;-) -- Steve > + list_for_each_entry(child, &dir->d_subdirs, d_u.d_child) > + child->d_inode->i_private = NULL; > + > list_del(&file->list); > - debugfs_remove_recursive(file->dir); > + debugfs_remove_recursive(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 > @@ -1274,10 +1251,9 @@ 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, > }; > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/