tracing: Cache comms only after an event occurred (7ffbd48d) · Commits · 戴 / test

kernel/trace/trace.c

+27 −8

Original line number	Diff line number	Diff line
		@@ -77,6 +77,13 @@ static int dummy_set_flag(u32 old_flags, u32 bit, int set)
		return 0;
		}

		/*
		* To prevent the comm cache from being overwritten when no
		* tracing is active, only save the comm when a trace event
		* occurred.
		*/
		static DEFINE_PER_CPU(bool, trace_cmdline_save);

		/*
		* Kill all tracing for good (never come back).
		* It is initialized to 1 but will turn to zero if the initialization
		@@ -1135,6 +1142,11 @@ void tracing_record_cmdline(struct task_struct *tsk)
		!tracing_is_on())
		return;

		if (!__this_cpu_read(trace_cmdline_save))
		return;

		__this_cpu_write(trace_cmdline_save, false);

		trace_save_cmdline(tsk);
		}

		@@ -1178,13 +1190,20 @@ trace_buffer_lock_reserve(struct ring_buffer *buffer,
		return event;
		}

		void
		__buffer_unlock_commit(struct ring_buffer buffer, struct ring_buffer_event event)
		{
		__this_cpu_write(trace_cmdline_save, true);
		ring_buffer_unlock_commit(buffer, event);
		}

		static inline void
		__trace_buffer_unlock_commit(struct ring_buffer *buffer,
		struct ring_buffer_event *event,
		unsigned long flags, int pc,
		int wake)
		{
		ring_buffer_unlock_commit(buffer, event);
		__buffer_unlock_commit(buffer, event);

		ftrace_trace_stack(buffer, flags, 6, pc);
		ftrace_trace_userstack(buffer, flags, pc);
		@@ -1232,7 +1251,7 @@ void trace_nowake_buffer_unlock_commit_regs(struct ring_buffer *buffer,
		unsigned long flags, int pc,
		struct pt_regs *regs)
		{
		ring_buffer_unlock_commit(buffer, event);
		__buffer_unlock_commit(buffer, event);

		ftrace_trace_stack_regs(buffer, flags, 0, pc, regs);
		ftrace_trace_userstack(buffer, flags, pc);
		@@ -1269,7 +1288,7 @@ trace_function(struct trace_array *tr,
		entry->parent_ip = parent_ip;

		if (!filter_check_discard(call, entry, buffer, event))
		ring_buffer_unlock_commit(buffer, event);
		__buffer_unlock_commit(buffer, event);
		}

		void
		@@ -1362,7 +1381,7 @@ static void __ftrace_trace_stack(struct ring_buffer *buffer,
		entry->size = trace.nr_entries;

		if (!filter_check_discard(call, entry, buffer, event))
		ring_buffer_unlock_commit(buffer, event);
		__buffer_unlock_commit(buffer, event);

		out:
		/* Again, don't let gcc optimize things here */
		@@ -1458,7 +1477,7 @@ ftrace_trace_userstack(struct ring_buffer *buffer, unsigned long flags, int pc)

		save_stack_trace_user(&trace);
		if (!filter_check_discard(call, entry, buffer, event))
		ring_buffer_unlock_commit(buffer, event);
		__buffer_unlock_commit(buffer, event);

		out_drop_count:
		__this_cpu_dec(user_stack_count);
		@@ -1653,7 +1672,7 @@ int trace_vbprintk(unsigned long ip, const char *fmt, va_list args)

		memcpy(entry->buf, tbuffer, sizeof(u32) * len);
		if (!filter_check_discard(call, entry, buffer, event)) {
		ring_buffer_unlock_commit(buffer, event);
		__buffer_unlock_commit(buffer, event);
		ftrace_trace_stack(buffer, flags, 6, pc);
		}

		@@ -1724,7 +1743,7 @@ int trace_array_vprintk(struct trace_array *tr,
		memcpy(&entry->buf, tbuffer, len);
		entry->buf[len] = '\0';
		if (!filter_check_discard(call, entry, buffer, event)) {
		ring_buffer_unlock_commit(buffer, event);
		__buffer_unlock_commit(buffer, event);
		ftrace_trace_stack(buffer, flags, 6, pc);
		}
		out:
		@@ -3993,7 +4012,7 @@ tracing_mark_write(struct file filp, const char __user ubuf,
		} else
		entry->buf[cnt] = '\0';

		ring_buffer_unlock_commit(buffer, event);
		__buffer_unlock_commit(buffer, event);

		written = cnt;

kernel/trace/trace.h

+3 −0

Original line number	Diff line number	Diff line
		@@ -359,6 +359,9 @@ struct trace_entry tracing_get_trace_entry(struct trace_array tr,
		struct trace_entry trace_find_next_entry(struct trace_iterator iter,
		int ent_cpu, u64 ent_ts);

		void __buffer_unlock_commit(struct ring_buffer *buffer,
		struct ring_buffer_event *event);

		int trace_empty(struct trace_iterator *iter);

		void trace_find_next_entry_inc(struct trace_iterator iter);

kernel/trace/trace_branch.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -77,7 +77,7 @@ probe_likely_condition(struct ftrace_branch_data *f, int val, int expect)
		entry->correct = val == expect;

		if (!filter_check_discard(call, entry, buffer, event))
		ring_buffer_unlock_commit(buffer, event);
		__buffer_unlock_commit(buffer, event);

		out:
		atomic_dec(&tr->data[cpu]->disabled);

kernel/trace/trace_functions_graph.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -223,7 +223,7 @@ int __trace_graph_entry(struct trace_array *tr,
		entry = ring_buffer_event_data(event);
		entry->graph_ent = *trace;
		if (!filter_current_check_discard(buffer, call, entry, event))
		ring_buffer_unlock_commit(buffer, event);
		__buffer_unlock_commit(buffer, event);

		return 1;
		}
		@@ -327,7 +327,7 @@ void __trace_graph_return(struct trace_array *tr,
		entry = ring_buffer_event_data(event);
		entry->ret = *trace;
		if (!filter_current_check_discard(buffer, call, entry, event))
		ring_buffer_unlock_commit(buffer, event);
		__buffer_unlock_commit(buffer, event);
		}

		void trace_graph_return(struct ftrace_graph_ret *trace)

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