From aa07d71f1bc7ea20e442e812b5de9d632b7f84c6 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (VMware)" Date: Fri, 11 Oct 2019 19:12:21 -0400 Subject: tracing: Have trace events system open call tracing_open_generic_tr() Instead of having the trace events system open call open code the taking of the trace_array descriptor (with trace_array_get()) and then calling trace_open_generic(), have it use the tracing_open_generic_tr() that does the combination of the two. This requires making tracing_open_generic_tr() global. Signed-off-by: Steven Rostedt (VMware) --- kernel/trace/trace.h | 1 + 1 file changed, 1 insertion(+) (limited to 'kernel/trace/trace.h') diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index f801d154ff6a..854dbf4050f8 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -681,6 +681,7 @@ void tracing_reset_online_cpus(struct trace_buffer *buf); void tracing_reset_current(int cpu); void tracing_reset_all_online_cpus(void); int tracing_open_generic(struct inode *inode, struct file *filp); +int tracing_open_generic_tr(struct inode *inode, struct file *filp); bool tracing_is_disabled(void); bool tracer_tracing_is_on(struct trace_array *tr); void tracer_tracing_on(struct trace_array *tr); -- cgit v1.2.3 From 8530dec63e7b486e3761cc3d74a22de301845ff5 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (VMware)" Date: Fri, 11 Oct 2019 17:39:57 -0400 Subject: tracing: Add tracing_check_open_get_tr() 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) --- kernel/trace/trace.h | 1 + 1 file changed, 1 insertion(+) (limited to 'kernel/trace/trace.h') 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); -- cgit v1.2.3