From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org
Cc: Ingo Molnar <mingo@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>
Subject: [for-linus][PATCH 05/11] tracing: Add tracing_check_open_get_tr()
Date: Sun, 13 Oct 2019 13:43:47 -0400 [thread overview]
Message-ID: <20191013174418.783120684@goodmis.org> (raw)
In-Reply-To: <20191013174342.381019558@goodmis.org>
From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
Currently, most files in the tracefs directory test if tracing_disabled is
set. If so, it should return -ENODEV. The tracing_disabled is called when
tracing is found to be broken. Originally it was done in case the ring
buffer was found to be corrupted, and we wanted to prevent reading it from
crashing the kernel. But it's also called if a tracing selftest fails on
boot. It's a one way switch. That is, once it is triggered, tracing is
disabled until reboot.
As most tracefs files can also be used by instances in the tracefs
directory, they need to be carefully done. Each instance has a trace_array
associated to it, and when the instance is removed, the trace_array is
freed. But if an instance is opened with a reference to the trace_array,
then it requires looking up the trace_array to get its ref counter (as there
could be a race with it being deleted and the open itself). Once it is
found, a reference is added to prevent the instance from being removed (and
the trace_array associated with it freed).
Combine the two checks (tracing_disabled and trace_array_get()) into a
single helper function. This will also make it easier to add lockdown to
tracefs later.
Link: http://lkml.kernel.org/r/20191011135458.7399da44@gandalf.local.home
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
kernel/trace/ftrace.c | 7 +-
kernel/trace/trace.c | 117 +++++++++++++++++--------------
kernel/trace/trace.h | 1 +
kernel/trace/trace_dynevent.c | 4 ++
kernel/trace/trace_events.c | 10 +--
kernel/trace/trace_events_hist.c | 2 +-
6 files changed, 81 insertions(+), 60 deletions(-)
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 32c2eb167de0..8b765a55e01c 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -3547,7 +3547,7 @@ ftrace_regex_open(struct ftrace_ops *ops, int flag,
if (unlikely(ftrace_disabled))
return -ENODEV;
- if (tr && trace_array_get(tr) < 0)
+ if (tracing_check_open_get_tr(tr))
return -ENODEV;
iter = kzalloc(sizeof(*iter), GFP_KERNEL);
@@ -6546,8 +6546,9 @@ ftrace_pid_open(struct inode *inode, struct file *file)
struct seq_file *m;
int ret = 0;
- if (trace_array_get(tr) < 0)
- return -ENODEV;
+ ret = tracing_check_open_get_tr(tr);
+ if (ret)
+ return ret;
if ((file->f_mode & FMODE_WRITE) &&
(file->f_flags & O_TRUNC))
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 94f1b9124939..26ee280f852b 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -304,6 +304,17 @@ void trace_array_put(struct trace_array *this_tr)
mutex_unlock(&trace_types_lock);
}
+int tracing_check_open_get_tr(struct trace_array *tr)
+{
+ if (tracing_disabled)
+ return -ENODEV;
+
+ if (tr && trace_array_get(tr) < 0)
+ return -ENODEV;
+
+ return 0;
+}
+
int call_filter_check_discard(struct trace_event_call *call, void *rec,
struct ring_buffer *buffer,
struct ring_buffer_event *event)
@@ -4140,8 +4151,11 @@ __tracing_open(struct inode *inode, struct file *file, bool snapshot)
int tracing_open_generic(struct inode *inode, struct file *filp)
{
- if (tracing_disabled)
- return -ENODEV;
+ int ret;
+
+ ret = tracing_check_open_get_tr(NULL);
+ if (ret)
+ return ret;
filp->private_data = inode->i_private;
return 0;
@@ -4159,12 +4173,11 @@ bool tracing_is_disabled(void)
int tracing_open_generic_tr(struct inode *inode, struct file *filp)
{
struct trace_array *tr = inode->i_private;
+ int ret;
- if (tracing_disabled)
- return -ENODEV;
-
- if (trace_array_get(tr) < 0)
- return -ENODEV;
+ ret = tracing_check_open_get_tr(tr);
+ if (ret)
+ return ret;
filp->private_data = inode->i_private;
@@ -4233,10 +4246,11 @@ static int tracing_open(struct inode *inode, struct file *file)
{
struct trace_array *tr = inode->i_private;
struct trace_iterator *iter;
- int ret = 0;
+ int ret;
- if (trace_array_get(tr) < 0)
- return -ENODEV;
+ ret = tracing_check_open_get_tr(tr);
+ if (ret)
+ return ret;
/* If this file was open for write, then erase contents */
if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC)) {
@@ -4352,11 +4366,9 @@ static int show_traces_open(struct inode *inode, struct file *file)
struct seq_file *m;
int ret;
- if (tracing_disabled)
- return -ENODEV;
-
- if (trace_array_get(tr) < 0)
- return -ENODEV;
+ ret = tracing_check_open_get_tr(tr);
+ if (ret)
+ return ret;
ret = seq_open(file, &show_traces_seq_ops);
if (ret) {
@@ -4710,11 +4722,9 @@ static int tracing_trace_options_open(struct inode *inode, struct file *file)
struct trace_array *tr = inode->i_private;
int ret;
- if (tracing_disabled)
- return -ENODEV;
-
- if (trace_array_get(tr) < 0)
- return -ENODEV;
+ ret = tracing_check_open_get_tr(tr);
+ if (ret)
+ return ret;
ret = single_open(file, tracing_trace_options_show, inode->i_private);
if (ret < 0)
@@ -5051,8 +5061,11 @@ static const struct seq_operations tracing_saved_tgids_seq_ops = {
static int tracing_saved_tgids_open(struct inode *inode, struct file *filp)
{
- if (tracing_disabled)
- return -ENODEV;
+ int ret;
+
+ ret = tracing_check_open_get_tr(NULL);
+ if (ret)
+ return ret;
return seq_open(filp, &tracing_saved_tgids_seq_ops);
}
@@ -5128,8 +5141,11 @@ static const struct seq_operations tracing_saved_cmdlines_seq_ops = {
static int tracing_saved_cmdlines_open(struct inode *inode, struct file *filp)
{
- if (tracing_disabled)
- return -ENODEV;
+ int ret;
+
+ ret = tracing_check_open_get_tr(NULL);
+ if (ret)
+ return ret;
return seq_open(filp, &tracing_saved_cmdlines_seq_ops);
}
@@ -5293,8 +5309,11 @@ static const struct seq_operations tracing_eval_map_seq_ops = {
static int tracing_eval_map_open(struct inode *inode, struct file *filp)
{
- if (tracing_disabled)
- return -ENODEV;
+ int ret;
+
+ ret = tracing_check_open_get_tr(NULL);
+ if (ret)
+ return ret;
return seq_open(filp, &tracing_eval_map_seq_ops);
}
@@ -5817,13 +5836,11 @@ static int tracing_open_pipe(struct inode *inode, struct file *filp)
{
struct trace_array *tr = inode->i_private;
struct trace_iterator *iter;
- int ret = 0;
-
- if (tracing_disabled)
- return -ENODEV;
+ int ret;
- if (trace_array_get(tr) < 0)
- return -ENODEV;
+ ret = tracing_check_open_get_tr(tr);
+ if (ret)
+ return ret;
mutex_lock(&trace_types_lock);
@@ -6560,11 +6577,9 @@ static int tracing_clock_open(struct inode *inode, struct file *file)
struct trace_array *tr = inode->i_private;
int ret;
- if (tracing_disabled)
- return -ENODEV;
-
- if (trace_array_get(tr))
- return -ENODEV;
+ ret = tracing_check_open_get_tr(tr);
+ if (ret)
+ return ret;
ret = single_open(file, tracing_clock_show, inode->i_private);
if (ret < 0)
@@ -6594,11 +6609,9 @@ static int tracing_time_stamp_mode_open(struct inode *inode, struct file *file)
struct trace_array *tr = inode->i_private;
int ret;
- if (tracing_disabled)
- return -ENODEV;
-
- if (trace_array_get(tr))
- return -ENODEV;
+ ret = tracing_check_open_get_tr(tr);
+ if (ret)
+ return ret;
ret = single_open(file, tracing_time_stamp_mode_show, inode->i_private);
if (ret < 0)
@@ -6651,10 +6664,11 @@ static int tracing_snapshot_open(struct inode *inode, struct file *file)
struct trace_array *tr = inode->i_private;
struct trace_iterator *iter;
struct seq_file *m;
- int ret = 0;
+ int ret;
- if (trace_array_get(tr) < 0)
- return -ENODEV;
+ ret = tracing_check_open_get_tr(tr);
+ if (ret)
+ return ret;
if (file->f_mode & FMODE_READ) {
iter = __tracing_open(inode, file, true);
@@ -7118,8 +7132,9 @@ static int tracing_err_log_open(struct inode *inode, struct file *file)
struct trace_array *tr = inode->i_private;
int ret = 0;
- if (trace_array_get(tr) < 0)
- return -ENODEV;
+ ret = tracing_check_open_get_tr(tr);
+ if (ret)
+ return ret;
/* If this file was opened for write, then erase contents */
if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC))
@@ -7170,11 +7185,9 @@ static int tracing_buffers_open(struct inode *inode, struct file *filp)
struct ftrace_buffer_info *info;
int ret;
- if (tracing_disabled)
- return -ENODEV;
-
- if (trace_array_get(tr) < 0)
- return -ENODEV;
+ ret = tracing_check_open_get_tr(tr);
+ if (ret)
+ return ret;
info = kzalloc(sizeof(*info), GFP_KERNEL);
if (!info) {
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 854dbf4050f8..d685c61085c0 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -338,6 +338,7 @@ extern struct mutex trace_types_lock;
extern int trace_array_get(struct trace_array *tr);
extern void trace_array_put(struct trace_array *tr);
+extern int tracing_check_open_get_tr(struct trace_array *tr);
extern int tracing_set_time_stamp_abs(struct trace_array *tr, bool abs);
extern int tracing_set_clock(struct trace_array *tr, const char *clockstr);
diff --git a/kernel/trace/trace_dynevent.c b/kernel/trace/trace_dynevent.c
index a41fed46c285..89779eb84a07 100644
--- a/kernel/trace/trace_dynevent.c
+++ b/kernel/trace/trace_dynevent.c
@@ -174,6 +174,10 @@ static int dyn_event_open(struct inode *inode, struct file *file)
{
int ret;
+ ret = tracing_check_open_get_tr(NULL);
+ if (ret)
+ return ret;
+
if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC)) {
ret = dyn_events_release_all(NULL);
if (ret < 0)
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 9613a757c902..71ab0a3660f4 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -1794,8 +1794,9 @@ ftrace_event_set_open(struct inode *inode, struct file *file)
struct trace_array *tr = inode->i_private;
int ret;
- if (trace_array_get(tr) < 0)
- return -ENODEV;
+ ret = tracing_check_open_get_tr(tr);
+ if (ret)
+ return ret;
if ((file->f_mode & FMODE_WRITE) &&
(file->f_flags & O_TRUNC))
@@ -1814,8 +1815,9 @@ ftrace_event_set_pid_open(struct inode *inode, struct file *file)
struct trace_array *tr = inode->i_private;
int ret;
- if (trace_array_get(tr) < 0)
- return -ENODEV;
+ ret = tracing_check_open_get_tr(tr);
+ if (ret)
+ return ret;
if ((file->f_mode & FMODE_WRITE) &&
(file->f_flags & O_TRUNC))
diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 9468bd8d44a2..dd18d76bf1bd 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -1680,7 +1680,7 @@ static int save_hist_vars(struct hist_trigger_data *hist_data)
if (var_data)
return 0;
- if (trace_array_get(tr) < 0)
+ if (tracing_check_open_get_tr(tr))
return -ENODEV;
var_data = kzalloc(sizeof(*var_data), GFP_KERNEL);
--
2.23.0
next prev parent reply other threads:[~2019-10-13 17:44 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-13 17:43 [for-linus][PATCH 00/11] tracing: Fixes for v5.4-rc2 Steven Rostedt
2019-10-13 17:43 ` [for-linus][PATCH 01/11] tracefs: Revert ccbd54ff54e8 ("tracefs: Restrict tracefs when the kernel is locked down") Steven Rostedt
2019-10-13 17:43 ` [for-linus][PATCH 02/11] ftrace: Get a reference counter for the trace_array on filter files Steven Rostedt
2019-10-13 17:43 ` [for-linus][PATCH 03/11] tracing: Get trace_array reference for available_tracers files Steven Rostedt
2019-10-13 17:43 ` [for-linus][PATCH 04/11] tracing: Have trace events system open call tracing_open_generic_tr() Steven Rostedt
2019-10-13 17:43 ` Steven Rostedt [this message]
2019-10-13 17:43 ` [for-linus][PATCH 06/11] tracing: Add locked_down checks to the open calls of files created for tracefs Steven Rostedt
2019-10-13 17:43 ` [for-linus][PATCH 07/11] tracing: Do not create tracefs files if tracefs lockdown is in effect Steven Rostedt
2019-10-13 17:43 ` [for-linus][PATCH 09/11] tracing/hwlat: Report total time spent in all NMIs during the sample Steven Rostedt
2019-10-13 17:43 ` [for-linus][PATCH 10/11] tracing/hwlat: Dont ignore outer-loop duration when calculating max_latency Steven Rostedt
2019-10-13 17:43 ` [for-linus][PATCH 11/11] tracing: Initialize iter->seq after zeroing in tracing_read_pipe() Steven Rostedt
[not found] ` <20191013174419.228868312@goodmis.org>
2019-10-13 18:57 ` [for-linus][PATCH 08/11] recordmcount: Fix nop_mcount() function Steven Rostedt
2019-10-13 19:14 ` Uwe Kleine-König
2019-10-13 19:53 ` Steven Rostedt
2019-10-13 20:03 ` Steven Rostedt
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20191013174418.783120684@goodmis.org \
--to=rostedt@goodmis.org \
--cc=akpm@linux-foundation.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
Powered by JetHome