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tracing: Prevent deleting instances when they are being read

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Add a ref count to the trace_array structure and prevent removal
of instances that have open descriptors.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt (Red Hat) 2013-03-06 15:27:24 -05:00 committed by Steven Rostedt
parent 121aaee7b0
commit a695cb5816
2 changed files with 24 additions and 0 deletions
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23
kernel/trace/trace.c
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@ -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);

1
kernel/trace/trace.h
View File

@ -219,6 +219,7 @@ struct trace_array {
struct list_head systems;
struct list_head events;
struct task_struct *waiter;
int ref;
};
enum {