From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1A2342031C for ; Tue, 31 Oct 2023 17:05:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="Kb4CZf/h" Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 6BA5C2105; Tue, 31 Oct 2023 10:05:33 -0700 (PDT) Received: from CPC-beaub-VBQ1L. (unknown [4.155.48.123]) by linux.microsoft.com (Postfix) with ESMTPSA id BB4B920B74C0; Tue, 31 Oct 2023 10:05:32 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com BB4B920B74C0 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1698771932; bh=fblPO5jXGp2VzBMVMfmWWPtvOiCMzdbt2sEWj0FwmbA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Kb4CZf/hvQs32c2GkISvCPoFAAd/ul+9KIqTNSeYL7VQnlGfcMa7AN7oZlDQ3NLDW VcH09P5LVLVUq3bOtPqrvLMei7COZnQ28U7jytvTAqU6pK7BqcnlYkrZxEF1dgxA93 lHrK1y2ZxcbifiHXW2+v3y0YxfJWVvc/RKmK/2gM= Date: Tue, 31 Oct 2023 17:05:31 +0000 From: Beau Belgrave To: Steven Rostedt Cc: Naresh Kamboju , "open list:KERNEL SELFTEST FRAMEWORK" , open list , linux-trace-kernel@vger.kernel.org, lkft-triage@lists.linaro.org, Mark Brown , Zheng Yejian , Dan Carpenter , Arnd Bergmann , Masami Hiramatsu , stable Subject: Re: selftests: user_events: ftrace_test - RIP: 0010:tracing_update_buffers (kernel/trace/trace.c:6470) Message-ID: <20231031170531.GB199-beaub@linux.microsoft.com> References: <20231027192011.GA436-beaub@linux.microsoft.com> <20231027183640.2529ab68@gandalf.local.home> <20231027223344.3854ac1f@rorschach.local.home> <20231030163102.GA1853-beaub@linux.microsoft.com> <20231030124223.4e4ddeb8@gandalf.local.home> <20231030173151.0631169b@gandalf.local.home> <20231031002707.GA107-beaub@linux.microsoft.com> <20231031000031.1e705592@gandalf.local.home> <20231031104551.6e0f3620@gandalf.local.home> <20231031120702.70dbb21b@gandalf.local.home> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20231031120702.70dbb21b@gandalf.local.home> On Tue, Oct 31, 2023 at 12:07:02PM -0400, Steven Rostedt wrote: > On Tue, 31 Oct 2023 10:45:51 -0400 > Steven Rostedt wrote: > > > @@ -1404,7 +1424,7 @@ event_enable_write(struct file *filp, const char __user *ubuf, size_t cnt, > > ret = -ENODEV; > > mutex_lock(&event_mutex); > > file = event_file_data(filp); > > - if (likely(file)) { > > + if (likely(file && !(file->flags & EVENT_FILE_FL_FREED))) { > > printk("update file = %px\n", file); > > printk("update tr = %px\n", file->tr); > > ret = tracing_update_buffers(file->tr); > > Well, this won't apply because I still had debugging in it when I added > these changes. > > Here's a better version: > Thanks! I ended up testing the official patch [1] instead of this one along with patches [2][3] in the next branch. My printk's are now good, everything looks back to normal for my repro. I added my Tested-by onto the official patch thread. Thanks, -Beau 1. https://lore.kernel.org/linux-trace-kernel/20231031122453.7a48b923@gandalf.local.home/ 2. https://lore.kernel.org/linux-trace-kernel/20231030114047.759c7bdf@gandalf.local.home 3. https://lore.kernel.org/linux-trace-kernel/20231028164650.4f5ea18a@rorschach.local.home/ > diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h > index 12207dc6722d..696f8dc4aa53 100644 > --- a/include/linux/trace_events.h > +++ b/include/linux/trace_events.h > @@ -492,6 +492,7 @@ enum { > EVENT_FILE_FL_TRIGGER_COND_BIT, > EVENT_FILE_FL_PID_FILTER_BIT, > EVENT_FILE_FL_WAS_ENABLED_BIT, > + EVENT_FILE_FL_FREED_BIT, > }; > > extern struct trace_event_file *trace_get_event_file(const char *instance, > @@ -630,6 +631,7 @@ extern int __kprobe_event_add_fields(struct dynevent_cmd *cmd, ...); > * TRIGGER_COND - When set, one or more triggers has an associated filter > * PID_FILTER - When set, the event is filtered based on pid > * WAS_ENABLED - Set when enabled to know to clear trace on module removal > + * FREED - File descriptor is freed, all fields should be considered invalid > */ > enum { > EVENT_FILE_FL_ENABLED = (1 << EVENT_FILE_FL_ENABLED_BIT), > @@ -643,6 +645,7 @@ enum { > EVENT_FILE_FL_TRIGGER_COND = (1 << EVENT_FILE_FL_TRIGGER_COND_BIT), > EVENT_FILE_FL_PID_FILTER = (1 << EVENT_FILE_FL_PID_FILTER_BIT), > EVENT_FILE_FL_WAS_ENABLED = (1 << EVENT_FILE_FL_WAS_ENABLED_BIT), > + EVENT_FILE_FL_FREED = (1 << EVENT_FILE_FL_FREED_BIT), > }; > > struct trace_event_file { > @@ -671,6 +674,7 @@ struct trace_event_file { > * caching and such. Which is mostly OK ;-) > */ > unsigned long flags; > + atomic_t ref; /* ref count for opened files */ > atomic_t sm_ref; /* soft-mode reference counter */ > atomic_t tm_ref; /* trigger-mode reference counter */ > }; > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c > index 2539cfc20a97..9aebf904ff97 100644 > --- a/kernel/trace/trace.c > +++ b/kernel/trace/trace.c > @@ -4978,6 +4978,20 @@ int tracing_open_file_tr(struct inode *inode, struct file *filp) > if (ret) > return ret; > > + mutex_lock(&event_mutex); > + > + /* Fail if the file is marked for removal */ > + if (file->flags & EVENT_FILE_FL_FREED) { > + trace_array_put(file->tr); > + ret = -ENODEV; > + } else { > + event_file_get(file); > + } > + > + mutex_unlock(&event_mutex); > + if (ret) > + return ret; > + > filp->private_data = inode->i_private; > > return 0; > @@ -4988,6 +5002,7 @@ int tracing_release_file_tr(struct inode *inode, struct file *filp) > struct trace_event_file *file = inode->i_private; > > trace_array_put(file->tr); > + event_file_put(file); > > return 0; > } > diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h > index 0e1405abf4f7..b7f4ea25a194 100644 > --- a/kernel/trace/trace.h > +++ b/kernel/trace/trace.h > @@ -1669,6 +1669,9 @@ extern void event_trigger_unregister(struct event_command *cmd_ops, > char *glob, > struct event_trigger_data *trigger_data); > > +extern void event_file_get(struct trace_event_file *file); > +extern void event_file_put(struct trace_event_file *file); > + > /** > * struct event_trigger_ops - callbacks for trace event triggers > * > diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c > index f9e3e24d8796..f29e815ca5b2 100644 > --- a/kernel/trace/trace_events.c > +++ b/kernel/trace/trace_events.c > @@ -990,13 +990,35 @@ static void remove_subsystem(struct trace_subsystem_dir *dir) > } > } > > +void event_file_get(struct trace_event_file *file) > +{ > + atomic_inc(&file->ref); > +} > + > +void event_file_put(struct trace_event_file *file) > +{ > + if (WARN_ON_ONCE(!atomic_read(&file->ref))) { > + if (file->flags & EVENT_FILE_FL_FREED) > + kmem_cache_free(file_cachep, file); > + return; > + } > + > + if (atomic_dec_and_test(&file->ref)) { > + /* Count should only go to zero when it is freed */ > + if (WARN_ON_ONCE(!(file->flags & EVENT_FILE_FL_FREED))) > + return; > + kmem_cache_free(file_cachep, file); > + } > +} > + > static void remove_event_file_dir(struct trace_event_file *file) > { > eventfs_remove_dir(file->ei); > list_del(&file->list); > remove_subsystem(file->system); > free_event_filter(file->filter); > - kmem_cache_free(file_cachep, file); > + file->flags |= EVENT_FILE_FL_FREED; > + event_file_put(file); > } > > /* > @@ -1369,7 +1391,7 @@ event_enable_read(struct file *filp, char __user *ubuf, size_t cnt, > flags = file->flags; > mutex_unlock(&event_mutex); > > - if (!file) > + if (!file || flags & EVENT_FILE_FL_FREED) > return -ENODEV; > > if (flags & EVENT_FILE_FL_ENABLED && > @@ -1403,7 +1425,7 @@ event_enable_write(struct file *filp, const char __user *ubuf, size_t cnt, > ret = -ENODEV; > mutex_lock(&event_mutex); > file = event_file_data(filp); > - if (likely(file)) { > + if (likely(file && !(file->flags & EVENT_FILE_FL_FREED))) { > ret = tracing_update_buffers(file->tr); > if (ret < 0) { > mutex_unlock(&event_mutex); > @@ -1683,7 +1705,7 @@ event_filter_read(struct file *filp, char __user *ubuf, size_t cnt, > > mutex_lock(&event_mutex); > file = event_file_data(filp); > - if (file) > + if (file && !(file->flags & EVENT_FILE_FL_FREED)) > print_event_filter(file, s); > mutex_unlock(&event_mutex); > > @@ -2902,6 +2924,7 @@ trace_create_new_event(struct trace_event_call *call, > atomic_set(&file->tm_ref, 0); > INIT_LIST_HEAD(&file->triggers); > list_add(&file->list, &tr->events); > + event_file_get(file); > > return file; > } > diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c > index 33264e510d16..0c611b281a5b 100644 > --- a/kernel/trace/trace_events_filter.c > +++ b/kernel/trace/trace_events_filter.c > @@ -2349,6 +2349,9 @@ int apply_event_filter(struct trace_event_file *file, char *filter_string) > struct event_filter *filter = NULL; > int err; > > + if (file->flags & EVENT_FILE_FL_FREED) > + return -ENODEV; > + > if (!strcmp(strstrip(filter_string), "0")) { > filter_disable(file); > filter = event_filter(file);