From a695cb5816228f86576f5f5c6809fdf8ed382ece Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Red Hat)" Date: Wed, 6 Mar 2013 15:27:24 -0500 Subject: [PATCH] tracing: Prevent deleting instances when they are being read Add a ref count to the trace_array structure and prevent removal of instances that have open descriptors. Signed-off-by: Steven Rostedt --- kernel/trace/trace.c | 23 +++++++++++++++++++++++ kernel/trace/trace.h | 1 + 2 files changed, 24 insertions(+) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index c547ebbe36ff..3a89496dc99b 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -2613,6 +2613,8 @@ __tracing_open(struct inode *inode, struct file *file, bool snapshot) tracing_iter_reset(iter, cpu); } + tr->ref++; + mutex_unlock(&trace_types_lock); return iter; @@ -2649,6 +2651,10 @@ static int tracing_release(struct inode *inode, struct file *file) tr = iter->tr; mutex_lock(&trace_types_lock); + + WARN_ON(!tr->ref); + tr->ref--; + for_each_tracing_cpu(cpu) { if (iter->buffer_iter[cpu]) ring_buffer_read_finish(iter->buffer_iter[cpu]); @@ -4460,6 +4466,10 @@ static int tracing_buffers_open(struct inode *inode, struct file *filp) if (!info) return -ENOMEM; + mutex_lock(&trace_types_lock); + + tr->ref++; + info->iter.tr = tr; info->iter.cpu_file = tc->cpu; info->iter.trace = tr->current_trace; @@ -4470,6 +4480,8 @@ static int tracing_buffers_open(struct inode *inode, struct file *filp) filp->private_data = info; + mutex_unlock(&trace_types_lock); + return nonseekable_open(inode, filp); } @@ -4568,10 +4580,17 @@ static int tracing_buffers_release(struct inode *inode, struct file *file) struct ftrace_buffer_info *info = file->private_data; struct trace_iterator *iter = &info->iter; + mutex_lock(&trace_types_lock); + + WARN_ON(!iter->tr->ref); + iter->tr->ref--; + if (info->spare) ring_buffer_free_read_page(iter->trace_buffer->buffer, info->spare); kfree(info); + mutex_unlock(&trace_types_lock); + return 0; } @@ -5411,6 +5430,10 @@ static int instance_delete(const char *name) if (!found) goto out_unlock; + ret = -EBUSY; + if (tr->ref) + goto out_unlock; + list_del(&tr->list); event_trace_del_tracer(tr); diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 1a456c291a07..f4931821a966 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -219,6 +219,7 @@ struct trace_array { struct list_head systems; struct list_head events; struct task_struct *waiter; + int ref; }; enum { -- 2.11.0