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authorSteven Rostedt (VMware) <rostedt@goodmis.org>2019-10-11 18:19:17 -0400
committerSteven Rostedt (VMware) <rostedt@goodmis.org>2019-10-12 20:40:50 -0400
commit194c2c74f5532e62c218adeb8e2b683119503907 (patch)
tree968137a7e069521734daacde26c23244ca1c2089
parent9ef16693aff8137faa21d16ffe65bb9832d24d71 (diff)
downloadlinux-stericsson-194c2c74f5532e62c218adeb8e2b683119503907.tar.gz
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.c17
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