From 7ef282e05132d56b6f6b71e3873f317664bea78b Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (VMware)" Date: Mon, 29 Jun 2020 23:45:56 -0400 Subject: tracing: Move pipe reference to trace array instead of current_tracer If a process has the trace_pipe open on a trace_array, the current tracer for that trace array should not be changed. This was original enforced by a global lock, but when instances were introduced, it was moved to the current_trace. But this structure is shared by all instances, and a trace_pipe is for a single instance. There's no reason that a process that has trace_pipe open on one instance should prevent another instance from changing its current tracer. Move the reference counter to the trace_array instead. This is marked as "Fixes" but is more of a clean up than a true fix. Backport if you want, but its not critical. Fixes: cf6ab6d9143b1 ("tracing: Add ref count to tracer for when they are being read by pipe") Signed-off-by: Steven Rostedt (VMware) --- kernel/trace/trace.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/trace/trace.h') diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 13db4000af3f..f21607f87189 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -356,6 +356,7 @@ struct trace_array { struct trace_event_file *trace_marker_file; cpumask_var_t tracing_cpumask; /* only trace on set CPUs */ int ref; + int trace_ref; #ifdef CONFIG_FUNCTION_TRACER struct ftrace_ops *ops; struct trace_pid_list __rcu *function_pids; @@ -547,7 +548,6 @@ struct tracer { struct tracer *next; struct tracer_flags *flags; int enabled; - int ref; bool print_max; bool allow_instances; #ifdef CONFIG_TRACER_MAX_TRACE -- cgit v1.2.3-70-g09d2 From c58b6b0372de0d4cd0536d6585addd1b36b151ae Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Fri, 24 Jul 2020 20:50:48 -0400 Subject: ftrace: Fix ftrace_trace_task return value I was attempting to use pid filtering with function_graph, but it wasn't allowing anything to make it through. Turns out ftrace_trace_task returns false if ftrace_ignore_pid is not-empty, which isn't correct anymore. We're now setting it to FTRACE_PID_IGNORE if we need to ignore that pid, otherwise it's set to the pid (which is weird considering the name) or to FTRACE_PID_TRACE. Fix the check to check for != FTRACE_PID_IGNORE. With this we can now use function_graph with pid filtering. Link: https://lkml.kernel.org/r/20200725005048.1790-1-josef@toxicpanda.com Fixes: 717e3f5ebc82 ("ftrace: Make function trace pid filtering a bit more exact") Signed-off-by: Josef Bacik Signed-off-by: Steven Rostedt (VMware) --- kernel/trace/ftrace.c | 3 --- kernel/trace/trace.h | 7 ++++++- 2 files changed, 6 insertions(+), 4 deletions(-) (limited to 'kernel/trace/trace.h') diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index f433cb44300a..4e3a5d79c078 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -139,9 +139,6 @@ static inline void ftrace_ops_init(struct ftrace_ops *ops) #endif } -#define FTRACE_PID_IGNORE -1 -#define FTRACE_PID_TRACE -2 - static void ftrace_pid_func(unsigned long ip, unsigned long parent_ip, struct ftrace_ops *op, struct pt_regs *regs) { diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index f21607f87189..610d21355526 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -1103,6 +1103,10 @@ print_graph_function_flags(struct trace_iterator *iter, u32 flags) extern struct list_head ftrace_pids; #ifdef CONFIG_FUNCTION_TRACER + +#define FTRACE_PID_IGNORE -1 +#define FTRACE_PID_TRACE -2 + struct ftrace_func_command { struct list_head list; char *name; @@ -1114,7 +1118,8 @@ struct ftrace_func_command { extern bool ftrace_filter_param __initdata; static inline int ftrace_trace_task(struct trace_array *tr) { - return !this_cpu_read(tr->array_buffer.data->ftrace_ignore_pid); + return this_cpu_read(tr->array_buffer.data->ftrace_ignore_pid) != + FTRACE_PID_IGNORE; } extern int ftrace_is_dead(void); int ftrace_create_function_files(struct trace_array *tr, -- cgit v1.2.3-70-g09d2