Commit 2c7eea4c authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Ingo Molnar
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tracing: replace the crude (unsigned) -1 hackery 



Impact: cleanup

The command line recorder uses (unsigned) -1 to mark non mapped
entries in the pid to command line maps. The validity check is
completely unintuitive: idx >= SAVED_CMDLINES

There is no need for such casting games. Use a constant to mark
unmapped entries and check for that constant to make the code readable
and understandable.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 18aecd36

kernel/trace/trace.c

+7 −6
Original line number Diff line number Diff line
@@ -633,6 +633,7 @@ void tracing_reset_online_cpus(struct trace_array *tr) 
}



#define SAVED_CMDLINES 128

#define NO_CMDLINE_MAP UINT_MAX

static unsigned map_pid_to_cmdline[PID_MAX_DEFAULT+1];

static unsigned map_cmdline_to_pid[SAVED_CMDLINES];

static char saved_cmdlines[SAVED_CMDLINES][TASK_COMM_LEN];
@@ -644,8 +645,8 @@ static atomic_t trace_record_cmdline_disabled __read_mostly; 


static void trace_init_cmdlines(void)

{

	memset(&map_pid_to_cmdline, -1, sizeof(map_pid_to_cmdline));

	memset(&map_cmdline_to_pid, -1, sizeof(map_cmdline_to_pid));

	memset(&map_pid_to_cmdline, NO_CMDLINE_MAP, sizeof(map_pid_to_cmdline));

	memset(&map_cmdline_to_pid, NO_CMDLINE_MAP, sizeof(map_cmdline_to_pid));

	cmdline_idx = 0;

}
@@ -753,12 +754,12 @@ static void trace_save_cmdline(struct task_struct *tsk) 
		return;



	idx = map_pid_to_cmdline[tsk->pid];

	if (idx >= SAVED_CMDLINES) {

	if (idx == NO_CMDLINE_MAP) {

		idx = (cmdline_idx + 1) % SAVED_CMDLINES;



		map = map_cmdline_to_pid[idx];

		if (map <= PID_MAX_DEFAULT)

			map_pid_to_cmdline[map] = (unsigned)-1;

		if (map != NO_CMDLINE_MAP)

			map_pid_to_cmdline[map] = NO_CMDLINE_MAP;



		map_pid_to_cmdline[tsk->pid] = idx;
@@ -786,7 +787,7 @@ void trace_find_cmdline(int pid, char comm[]) 


	__raw_spin_lock(&trace_cmdline_lock);

	map = map_pid_to_cmdline[pid];

	if (map >= SAVED_CMDLINES)

	if (map == NO_CMDLINE_MAP)

		goto out;



	strcpy(comm, saved_cmdlines[map]);

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