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: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index d86e325..8031005 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1301,6 +1301,13 @@
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 @@
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 @@
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 @@
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 @@
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);