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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: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Thomas Gleixner 2009-03-18 09:03:19 +01:00 committed by Ingo Molnar
parent 18aecd362a
commit 2c7eea4c62
1 changed files with 7 additions and 6 deletions
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13
kernel/trace/trace.c
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@ -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]);