Commit 3d9101e9 authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Ingo Molnar
Browse files

trace: fix task state printout 



Impact: fix occasionally incorrect trace output

The tracing code has interesting varieties of printing out task state.

Unfortunalely only one of the instances is correct as it copies the
code from sched.c:sched_show_task(). The others are plain wrong as
they treatthe bitfield as an integer offset into the character
array. Also the size check of the character array is wrong as it
includes the trailing \0.

Use a common state decoder inline which does the Right Thing.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Acked-by: default avatarSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 55dac3a5

kernel/trace/trace.c

+17 −22
Original line number Diff line number Diff line
@@ -1301,6 +1301,13 @@ lat_print_timestamp(struct trace_seq *s, u64 abs_usecs, 


static const char state_to_char[] = TASK_STATE_TO_CHAR_STR;



static int task_state_char(unsigned long state)

{

	int bit = state ? __ffs(state) + 1 : 0;



	return bit < sizeof(state_to_char) - 1 ? state_to_char[bit] : '?';

}



/*

 * The message is supposed to contain an ending newline.

 * If the printing stops prematurely, try to add a newline of our own.
@@ -1396,12 +1403,8 @@ print_lat_fmt(struct trace_iterator *iter, unsigned int trace_idx, int cpu) 


		trace_assign_type(field, entry);



		T = field->next_state < sizeof(state_to_char) ?

			state_to_char[field->next_state] : 'X';



		state = field->prev_state ?

			__ffs(field->prev_state) + 1 : 0;

		S = state < sizeof(state_to_char) - 1 ? state_to_char[state] : 'X';

		T = task_state_char(field->next_state);

		S = task_state_char(field->prev_state);

		comm = trace_find_cmdline(field->next_pid);

		trace_seq_printf(s, " %5d:%3d:%c %s [%03d] %5d:%3d:%c %s\n",

				 field->prev_pid,
@@ -1519,10 +1522,8 @@ static enum print_line_t print_trace_fmt(struct trace_iterator *iter) 


		trace_assign_type(field, entry);



		S = field->prev_state < sizeof(state_to_char) ?

			state_to_char[field->prev_state] : 'X';

		T = field->next_state < sizeof(state_to_char) ?

			state_to_char[field->next_state] : 'X';

		T = task_state_char(field->next_state);

		S = task_state_char(field->prev_state);

		ret = trace_seq_printf(s, " %5d:%3d:%c %s [%03d] %5d:%3d:%c\n",

				       field->prev_pid,

				       field->prev_prio,
@@ -1621,12 +1622,9 @@ static enum print_line_t print_raw_fmt(struct trace_iterator *iter) 


		trace_assign_type(field, entry);



		S = field->prev_state < sizeof(state_to_char) ?

			state_to_char[field->prev_state] : 'X';

		T = field->next_state < sizeof(state_to_char) ?

			state_to_char[field->next_state] : 'X';

		if (entry->type == TRACE_WAKE)

			S = '+';

		T = task_state_char(field->next_state);

		S = entry->type == TRACE_WAKE ? '+' :

			task_state_char(field->prev_state);

		ret = trace_seq_printf(s, "%d %d %c %d %d %d %c\n",

				       field->prev_pid,

				       field->prev_prio,
@@ -1712,12 +1710,9 @@ static enum print_line_t print_hex_fmt(struct trace_iterator *iter) 


		trace_assign_type(field, entry);



		S = field->prev_state < sizeof(state_to_char) ?

			state_to_char[field->prev_state] : 'X';

		T = field->next_state < sizeof(state_to_char) ?

			state_to_char[field->next_state] : 'X';

		if (entry->type == TRACE_WAKE)

			S = '+';

		T = task_state_char(field->next_state);

		S = entry->type == TRACE_WAKE ? '+' :

			task_state_char(field->prev_state);

		SEQ_PUT_HEX_FIELD_RET(s, field->prev_pid);

		SEQ_PUT_HEX_FIELD_RET(s, field->prev_prio);

		SEQ_PUT_HEX_FIELD_RET(s, S);

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