ftrace: fix conversion of task state to char in latency tracer (d17d9691) · Commits · 戴 / test

The conversion of task states to a character in the sched_switch tracer (part of latency tracer infrastructure), seems to be incorrect. We currently do it by indexing into the state_to_char array using the state value. The state values do not map directly into the array index and are thus incorrect. The following patch addresses this issue. This is also what is being done even in the show_task() routine in kernel/sched.c The patch has been compile and run tested. Signed-off-by:

Ankita Garg <ankita@in.ibm.com> Signed-off-by:

Ingo Molnar <mingo@elte.hu> Signed-off-by:

Thomas Gleixner <tglx@linutronix.de>

kernel/trace/trace.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -1208,6 +1208,7 @@ print_lat_fmt(struct trace_iterator *iter, unsigned int trace_idx, int cpu)
		char *comm;
		int S, T;
		int i;
		unsigned state;

		if (!next_entry)
		next_entry = entry;
		@@ -1238,11 +1239,11 @@ print_lat_fmt(struct trace_iterator *iter, unsigned int trace_idx, int cpu)
		break;
		case TRACE_CTX:
		case TRACE_WAKE:
		S = entry->ctx.prev_state < sizeof(state_to_char) ?
		state_to_char[entry->ctx.prev_state] : 'X';
		T = entry->ctx.next_state < sizeof(state_to_char) ?
		state_to_char[entry->ctx.next_state] : 'X';

		state = entry->ctx.prev_state ? __ffs(entry->ctx.prev_state) + 1 : 0;
		S = state < sizeof(state_to_char) - 1 ? state_to_char[state] : 'X';
		comm = trace_find_cmdline(entry->ctx.next_pid);
		trace_seq_printf(s, " %5d:%3d:%c %s %5d:%3d:%c %s\n",
		entry->ctx.prev_pid,

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