tracing: Introduce saved_cmdlines_size file
Introduce saved_cmdlines_size file for changing the number of saved pid-comms. saved_cmdlines currently stores 128 command names using SAVED_CMDLINES, but 'no-existing processes' names are often lost in saved_cmdlines when we read the trace data. So, by introducing saved_cmdlines_size file, we can now change the 128 command names saved to something much larger if needed. When we write a value to saved_cmdlines_size, the number of the value will be stored in pid-comm list: # echo 1024 > /sys/kernel/debug/tracing/saved_cmdlines_size Here, 1024 command names can be stored. The default number is 128 and the maximum number is PID_MAX_DEFAULT (=32768 if CONFIG_BASE_SMALL is not set). So, if we want to avoid losing any command names, we need to set 32768 to saved_cmdlines_size. We can read the maximum number of the list: # cat /sys/kernel/debug/tracing/saved_cmdlines_size 128 Link: http://lkml.kernel.org/p/20140605012427.22115.16173.stgit@yunodevel Signed-off-by: Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Yoshihiro YUNOMAE
Steven Rostedt
Родитель
beba4bb096
Коммит
939c7a4f04
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@ -1285,22 +1285,71 @@ void tracing_reset_all_online_cpus(void)
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}
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}
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#define SAVED_CMDLINES 128
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#define SAVED_CMDLINES_DEFAULT 128
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#define NO_CMDLINE_MAP UINT_MAX
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static unsigned map_pid_to_cmdline[PID_MAX_DEFAULT+1];
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static unsigned map_cmdline_to_pid[SAVED_CMDLINES];
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static char saved_cmdlines[SAVED_CMDLINES][TASK_COMM_LEN];
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static int cmdline_idx;
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static arch_spinlock_t trace_cmdline_lock = __ARCH_SPIN_LOCK_UNLOCKED;
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struct saved_cmdlines_buffer {
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unsigned map_pid_to_cmdline[PID_MAX_DEFAULT+1];
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unsigned *map_cmdline_to_pid;
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unsigned cmdline_num;
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int cmdline_idx;
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char *saved_cmdlines;
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};
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static struct saved_cmdlines_buffer *savedcmd;
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/* temporary disable recording */
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static atomic_t trace_record_cmdline_disabled __read_mostly;
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static void trace_init_cmdlines(void)
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static inline char *get_saved_cmdlines(int idx)
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{
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memset(&map_pid_to_cmdline, NO_CMDLINE_MAP, sizeof(map_pid_to_cmdline));
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memset(&map_cmdline_to_pid, NO_CMDLINE_MAP, sizeof(map_cmdline_to_pid));
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cmdline_idx = 0;
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return &savedcmd->saved_cmdlines[idx * TASK_COMM_LEN];
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}
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static inline void set_cmdline(int idx, const char *cmdline)
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{
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memcpy(get_saved_cmdlines(idx), cmdline, TASK_COMM_LEN);
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}
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static int allocate_cmdlines_buffer(unsigned int val,
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struct saved_cmdlines_buffer *s)
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{
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s->map_cmdline_to_pid = kmalloc(val * sizeof(*s->map_cmdline_to_pid),
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GFP_KERNEL);
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if (!s->map_cmdline_to_pid)
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return -ENOMEM;
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s->saved_cmdlines = kmalloc(val * TASK_COMM_LEN, GFP_KERNEL);
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if (!s->saved_cmdlines) {
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kfree(s->map_cmdline_to_pid);
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return -ENOMEM;
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}
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s->cmdline_idx = 0;
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s->cmdline_num = val;
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memset(&s->map_pid_to_cmdline, NO_CMDLINE_MAP,
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sizeof(s->map_pid_to_cmdline));
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memset(s->map_cmdline_to_pid, NO_CMDLINE_MAP,
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val * sizeof(*s->map_cmdline_to_pid));
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return 0;
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}
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static int trace_create_savedcmd(void)
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{
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int ret;
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savedcmd = kmalloc(sizeof(struct saved_cmdlines_buffer), GFP_KERNEL);
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if (!savedcmd)
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return -ENOMEM;
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ret = allocate_cmdlines_buffer(SAVED_CMDLINES_DEFAULT, savedcmd);
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if (ret < 0) {
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kfree(savedcmd);
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savedcmd = NULL;
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return -ENOMEM;
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}
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return 0;
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}
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int is_tracing_stopped(void)
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@ -1457,9 +1506,9 @@ static int trace_save_cmdline(struct task_struct *tsk)
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if (!arch_spin_trylock(&trace_cmdline_lock))
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return 0;
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idx = map_pid_to_cmdline[tsk->pid];
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idx = savedcmd->map_pid_to_cmdline[tsk->pid];
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if (idx == NO_CMDLINE_MAP) {
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idx = (cmdline_idx + 1) % SAVED_CMDLINES;
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idx = (savedcmd->cmdline_idx + 1) % savedcmd->cmdline_num;
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/*
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* Check whether the cmdline buffer at idx has a pid
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@ -1467,17 +1516,17 @@ static int trace_save_cmdline(struct task_struct *tsk)
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* need to clear the map_pid_to_cmdline. Otherwise we
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* would read the new comm for the old pid.
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*/
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pid = map_cmdline_to_pid[idx];
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pid = savedcmd->map_cmdline_to_pid[idx];
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if (pid != NO_CMDLINE_MAP)
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map_pid_to_cmdline[pid] = NO_CMDLINE_MAP;
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savedcmd->map_pid_to_cmdline[pid] = NO_CMDLINE_MAP;
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map_cmdline_to_pid[idx] = tsk->pid;
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map_pid_to_cmdline[tsk->pid] = idx;
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savedcmd->map_cmdline_to_pid[idx] = tsk->pid;
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savedcmd->map_pid_to_cmdline[tsk->pid] = idx;
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cmdline_idx = idx;
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savedcmd->cmdline_idx = idx;
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}
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memcpy(&saved_cmdlines[idx], tsk->comm, TASK_COMM_LEN);
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set_cmdline(idx, tsk->comm);
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arch_spin_unlock(&trace_cmdline_lock);
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@ -1503,9 +1552,9 @@ static void __trace_find_cmdline(int pid, char comm[])
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return;
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}
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map = map_pid_to_cmdline[pid];
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map = savedcmd->map_pid_to_cmdline[pid];
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if (map != NO_CMDLINE_MAP)
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strcpy(comm, saved_cmdlines[map]);
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strcpy(comm, get_saved_cmdlines(map));
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else
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strcpy(comm, "<...>");
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}
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@ -3593,6 +3642,7 @@ static const char readme_msg[] =
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" trace_options\t\t- Set format or modify how tracing happens\n"
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"\t\t\t Disable an option by adding a suffix 'no' to the\n"
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"\t\t\t option name\n"
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" saved_cmdlines_size\t- echo command number in here to store comm-pid list\n"
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#ifdef CONFIG_DYNAMIC_FTRACE
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"\n available_filter_functions - list of functions that can be filtered on\n"
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" set_ftrace_filter\t- echo function name in here to only trace these\n"
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@ -3715,7 +3765,8 @@ static void *saved_cmdlines_next(struct seq_file *m, void *v, loff_t *pos)
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(*pos)++;
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for (; ptr < &map_cmdline_to_pid[SAVED_CMDLINES]; ptr++) {
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for (; ptr < &savedcmd->map_cmdline_to_pid[savedcmd->cmdline_num];
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ptr++) {
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if (*ptr == -1 || *ptr == NO_CMDLINE_MAP)
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continue;
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@ -3733,7 +3784,7 @@ static void *saved_cmdlines_start(struct seq_file *m, loff_t *pos)
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preempt_disable();
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arch_spin_lock(&trace_cmdline_lock);
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v = &map_cmdline_to_pid[0];
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v = &savedcmd->map_cmdline_to_pid[0];
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while (l <= *pos) {
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v = saved_cmdlines_next(m, v, &l);
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if (!v)
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@ -3781,6 +3832,79 @@ static const struct file_operations tracing_saved_cmdlines_fops = {
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.release = seq_release,
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};
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static ssize_t
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tracing_saved_cmdlines_size_read(struct file *filp, char __user *ubuf,
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size_t cnt, loff_t *ppos)
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{
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char buf[64];
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int r;
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arch_spin_lock(&trace_cmdline_lock);
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r = sprintf(buf, "%u\n", savedcmd->cmdline_num);
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arch_spin_unlock(&trace_cmdline_lock);
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return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
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}
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static void free_saved_cmdlines_buffer(struct saved_cmdlines_buffer *s)
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{
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kfree(s->saved_cmdlines);
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kfree(s->map_cmdline_to_pid);
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kfree(s);
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}
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static int tracing_resize_saved_cmdlines(unsigned int val)
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{
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struct saved_cmdlines_buffer *s, *savedcmd_temp;
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s = kmalloc(sizeof(struct saved_cmdlines_buffer), GFP_KERNEL);
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if (!s)
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return -ENOMEM;
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if (allocate_cmdlines_buffer(val, s) < 0) {
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kfree(s);
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return -ENOMEM;
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}
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arch_spin_lock(&trace_cmdline_lock);
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savedcmd_temp = savedcmd;
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savedcmd = s;
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arch_spin_unlock(&trace_cmdline_lock);
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free_saved_cmdlines_buffer(savedcmd_temp);
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return 0;
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}
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static ssize_t
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tracing_saved_cmdlines_size_write(struct file *filp, const char __user *ubuf,
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size_t cnt, loff_t *ppos)
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{
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unsigned long val;
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int ret;
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ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
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if (ret)
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return ret;
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/* must have at least 1 entry or less than PID_MAX_DEFAULT */
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if (!val || val > PID_MAX_DEFAULT)
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return -EINVAL;
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ret = tracing_resize_saved_cmdlines((unsigned int)val);
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if (ret < 0)
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return ret;
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*ppos += cnt;
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return cnt;
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}
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static const struct file_operations tracing_saved_cmdlines_size_fops = {
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.open = tracing_open_generic,
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.read = tracing_saved_cmdlines_size_read,
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.write = tracing_saved_cmdlines_size_write,
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};
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static ssize_t
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tracing_set_trace_read(struct file *filp, char __user *ubuf,
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size_t cnt, loff_t *ppos)
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@ -6375,6 +6499,9 @@ static __init int tracer_init_debugfs(void)
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trace_create_file("saved_cmdlines", 0444, d_tracer,
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NULL, &tracing_saved_cmdlines_fops);
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trace_create_file("saved_cmdlines_size", 0644, d_tracer,
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NULL, &tracing_saved_cmdlines_size_fops);
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#ifdef CONFIG_DYNAMIC_FTRACE
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trace_create_file("dyn_ftrace_total_info", 0444, d_tracer,
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&ftrace_update_tot_cnt, &tracing_dyn_info_fops);
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@ -6611,18 +6738,19 @@ __init static int tracer_alloc_buffers(void)
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if (!temp_buffer)
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goto out_free_cpumask;
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if (trace_create_savedcmd() < 0)
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goto out_free_temp_buffer;
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/* TODO: make the number of buffers hot pluggable with CPUS */
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if (allocate_trace_buffers(&global_trace, ring_buf_size) < 0) {
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printk(KERN_ERR "tracer: failed to allocate ring buffer!\n");
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WARN_ON(1);
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goto out_free_temp_buffer;
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goto out_free_savedcmd;
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}
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if (global_trace.buffer_disabled)
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tracing_off();
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trace_init_cmdlines();
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if (trace_boot_clock) {
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ret = tracing_set_clock(&global_trace, trace_boot_clock);
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if (ret < 0)
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@ -6668,6 +6796,8 @@ __init static int tracer_alloc_buffers(void)
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return 0;
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out_free_savedcmd:
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free_saved_cmdlines_buffer(savedcmd);
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out_free_temp_buffer:
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ring_buffer_free(temp_buffer);
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out_free_cpumask:
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