diff options
| author |   Steven Rostedt (VMware) <rostedt@goodmis.org> | 2019-10-11 18:19:17 -0400 |
|---|---|---|
| committer | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2019-10-12 20:40:50 -0400 |
| commit | 194c2c74f5532e62c218adeb8e2b683119503907 (patch) | |
| tree | 968137a7e069521734daacde26c23244ca1c2089 | |
| parent | ftrace: Get a reference counter for the trace_array on filter files (diff) | |
| download | linux-dev-194c2c74f5532e62c218adeb8e2b683119503907.tar.xz linux-dev-194c2c74f5532e62c218adeb8e2b683119503907.zip | |
tracing: Get trace_array reference for available_tracers files
As instances may have different tracers available, we need to look at the
trace_array descriptor that shows the list of the available tracers for the
instance. But there's a race between opening the file and an admin
deleting the instance. The trace_array_get() needs to be called before
accessing the trace_array.
Cc: stable@vger.kernel.org
Fixes: 607e2ea167e56 ("tracing: Set up infrastructure to allow tracers for instances")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| -rw-r--r-- | kernel/trace/trace.c | 17 |
1 files changed, 15 insertions, 2 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 252f79c435f8..fa7d813b04c6 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -4355,9 +4355,14 @@ static int show_traces_open(struct inode *inode, struct file *file) if (tracing_disabled) return -ENODEV; + if (trace_array_get(tr) < 0) + return -ENODEV; + ret = seq_open(file, &show_traces_seq_ops); - if (ret) + if (ret) { + trace_array_put(tr); return ret; + } m = file->private_data; m->private = tr; @@ -4365,6 +4370,14 @@ static int show_traces_open(struct inode *inode, struct file *file) return 0; } +static int show_traces_release(struct inode *inode, struct file *file) +{ + struct trace_array *tr = inode->i_private; + + trace_array_put(tr); + return seq_release(inode, file); +} + static ssize_t tracing_write_stub(struct file *filp, const char __user *ubuf, size_t count, loff_t *ppos) @@ -4395,8 +4408,8 @@ static const struct file_operations tracing_fops = { static const struct file_operations show_traces_fops = { .open = show_traces_open, .read = seq_read, - .release = seq_release, .llseek = seq_lseek, + .release = show_traces_release, }; static ssize_t |