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tracing: Move pid filtering into trace_pid.c

Browse source 
The trace.c file was a dumping ground for most tracing code. Start
organizing it better by moving various functions out into their own files.
Move the PID filtering functions from trace.c into its own trace_pid.c
file.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: https://patch.msgid.link/20260208032450.998330662@kernel.org
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt 2026-02-07 22:24:27 -05:00 • committed by Steven Rostedt (Google)
parent 27931ee8f4
commit 98021e37d6
3 changed files with 247 additions and 242 deletions
Download patch file Download diff file Expand all files Collapse all files

1
kernel/trace/Makefile
View file

@ -68,6 +68,7 @@ obj-$(CONFIG_TRACING) += trace_output.o
obj-$(CONFIG_TRACING) += trace_seq.o
obj-$(CONFIG_TRACING) += trace_stat.o
obj-$(CONFIG_TRACING) += trace_printk.o
obj-$(CONFIG_TRACING) += trace_pid.o
obj-$(CONFIG_TRACING) += pid_list.o
obj-$(CONFIG_TRACING_MAP) += tracing_map.o
obj-$(CONFIG_PREEMPTIRQ_DELAY_TEST) += preemptirq_delay_test.o

242
kernel/trace/trace.c
View file

@ -637,248 +637,6 @@ int tracing_check_open_get_tr(struct trace_array *tr)
return 0;
}
/**
* trace_find_filtered_pid - check if a pid exists in a filtered_pid list
* @filtered_pids: The list of pids to check
* @search_pid: The PID to find in @filtered_pids
*
* Returns true if @search_pid is found in @filtered_pids, and false otherwise.
*/
bool
trace_find_filtered_pid(struct trace_pid_list *filtered_pids, pid_t search_pid)
{
return trace_pid_list_is_set(filtered_pids, search_pid);
}
/**
* trace_ignore_this_task - should a task be ignored for tracing
* @filtered_pids: The list of pids to check
* @filtered_no_pids: The list of pids not to be traced
* @task: The task that should be ignored if not filtered
*
* Checks if @task should be traced or not from @filtered_pids.
* Returns true if @task should *NOT* be traced.
* Returns false if @task should be traced.
*/
bool
trace_ignore_this_task(struct trace_pid_list *filtered_pids,
struct trace_pid_list *filtered_no_pids,
struct task_struct *task)
{
/*
* If filtered_no_pids is not empty, and the task's pid is listed
* in filtered_no_pids, then return true.
* Otherwise, if filtered_pids is empty, that means we can
* trace all tasks. If it has content, then only trace pids
* within filtered_pids.
*/
return (filtered_pids &&
!trace_find_filtered_pid(filtered_pids, task->pid)) ||
(filtered_no_pids &&
trace_find_filtered_pid(filtered_no_pids, task->pid));
}
/**
* trace_filter_add_remove_task - Add or remove a task from a pid_list
* @pid_list: The list to modify
* @self: The current task for fork or NULL for exit
* @task: The task to add or remove
*
* If adding a task, if @self is defined, the task is only added if @self
* is also included in @pid_list. This happens on fork and tasks should
* only be added when the parent is listed. If @self is NULL, then the
* @task pid will be removed from the list, which would happen on exit
* of a task.
*/
void trace_filter_add_remove_task(struct trace_pid_list *pid_list,
struct task_struct *self,
struct task_struct *task)
{
if (!pid_list)
return;
/* For forks, we only add if the forking task is listed */
if (self) {
if (!trace_find_filtered_pid(pid_list, self->pid))
return;
}
/* "self" is set for forks, and NULL for exits */
if (self)
trace_pid_list_set(pid_list, task->pid);
else
trace_pid_list_clear(pid_list, task->pid);
}
/**
* trace_pid_next - Used for seq_file to get to the next pid of a pid_list
* @pid_list: The pid list to show
* @v: The last pid that was shown (+1 the actual pid to let zero be displayed)
* @pos: The position of the file
*
* This is used by the seq_file "next" operation to iterate the pids
* listed in a trace_pid_list structure.
*
* Returns the pid+1 as we want to display pid of zero, but NULL would
* stop the iteration.
*/
void *trace_pid_next(struct trace_pid_list *pid_list, void *v, loff_t *pos)
{
long pid = (unsigned long)v;
unsigned int next;
(*pos)++;
/* pid already is +1 of the actual previous bit */
if (trace_pid_list_next(pid_list, pid, &next) < 0)
return NULL;
pid = next;
/* Return pid + 1 to allow zero to be represented */
return (void *)(pid + 1);
}
/**
* trace_pid_start - Used for seq_file to start reading pid lists
* @pid_list: The pid list to show
* @pos: The position of the file
*
* This is used by seq_file "start" operation to start the iteration
* of listing pids.
*
* Returns the pid+1 as we want to display pid of zero, but NULL would
* stop the iteration.
*/
void *trace_pid_start(struct trace_pid_list *pid_list, loff_t *pos)
{
unsigned long pid;
unsigned int first;
loff_t l = 0;
if (trace_pid_list_first(pid_list, &first) < 0)
return NULL;
pid = first;
/* Return pid + 1 so that zero can be the exit value */
for (pid++; pid && l < *pos;
pid = (unsigned long)trace_pid_next(pid_list, (void *)pid, &l))
;
return (void *)pid;
}
/**
* trace_pid_show - show the current pid in seq_file processing
* @m: The seq_file structure to write into
* @v: A void pointer of the pid (+1) value to display
*
* Can be directly used by seq_file operations to display the current
* pid value.
*/
int trace_pid_show(struct seq_file *m, void *v)
{
unsigned long pid = (unsigned long)v - 1;
seq_printf(m, "%lu\n", pid);
return 0;
}
/* 128 should be much more than enough */
#define PID_BUF_SIZE 127
int trace_pid_write(struct trace_pid_list *filtered_pids,
struct trace_pid_list **new_pid_list,
const char __user *ubuf, size_t cnt)
{
struct trace_pid_list *pid_list;
struct trace_parser parser;
unsigned long val;
int nr_pids = 0;
ssize_t read = 0;
ssize_t ret;
loff_t pos;
pid_t pid;
if (trace_parser_get_init(&parser, PID_BUF_SIZE + 1))
return -ENOMEM;
/*
* Always recreate a new array. The write is an all or nothing
* operation. Always create a new array when adding new pids by
* the user. If the operation fails, then the current list is
* not modified.
*/
pid_list = trace_pid_list_alloc();
if (!pid_list) {
trace_parser_put(&parser);
return -ENOMEM;
}
if (filtered_pids) {
/* copy the current bits to the new max */
ret = trace_pid_list_first(filtered_pids, &pid);
while (!ret) {
ret = trace_pid_list_set(pid_list, pid);
if (ret < 0)
goto out;
ret = trace_pid_list_next(filtered_pids, pid + 1, &pid);
nr_pids++;
}
}
ret = 0;
while (cnt > 0) {
pos = 0;
ret = trace_get_user(&parser, ubuf, cnt, &pos);
if (ret < 0)
break;
read += ret;
ubuf += ret;
cnt -= ret;
if (!trace_parser_loaded(&parser))
break;
ret = -EINVAL;
if (kstrtoul(parser.buffer, 0, &val))
break;
pid = (pid_t)val;
if (trace_pid_list_set(pid_list, pid) < 0) {
ret = -1;
break;
}
nr_pids++;
trace_parser_clear(&parser);
ret = 0;
}
out:
trace_parser_put(&parser);
if (ret < 0) {
trace_pid_list_free(pid_list);
return ret;
}
if (!nr_pids) {
/* Cleared the list of pids */
trace_pid_list_free(pid_list);
pid_list = NULL;
}
*new_pid_list = pid_list;
return read;
}
static u64 buffer_ftrace_now(struct array_buffer *buf, int cpu)
{
u64 ts;

246
kernel/trace/trace_pid.c Normal file
View file

@ -0,0 +1,246 @@
// SPDX-License-Identifier: GPL-2.0
#include "trace.h"
/**
* trace_find_filtered_pid - check if a pid exists in a filtered_pid list
* @filtered_pids: The list of pids to check
* @search_pid: The PID to find in @filtered_pids
*
* Returns true if @search_pid is found in @filtered_pids, and false otherwise.
*/
bool
trace_find_filtered_pid(struct trace_pid_list *filtered_pids, pid_t search_pid)
{
return trace_pid_list_is_set(filtered_pids, search_pid);
}
/**
* trace_ignore_this_task - should a task be ignored for tracing
* @filtered_pids: The list of pids to check
* @filtered_no_pids: The list of pids not to be traced
* @task: The task that should be ignored if not filtered
*
* Checks if @task should be traced or not from @filtered_pids.
* Returns true if @task should *NOT* be traced.
* Returns false if @task should be traced.
*/
bool
trace_ignore_this_task(struct trace_pid_list *filtered_pids,
struct trace_pid_list *filtered_no_pids,
struct task_struct *task)
{
/*
* If filtered_no_pids is not empty, and the task's pid is listed
* in filtered_no_pids, then return true.
* Otherwise, if filtered_pids is empty, that means we can
* trace all tasks. If it has content, then only trace pids
* within filtered_pids.
*/
return (filtered_pids &&
!trace_find_filtered_pid(filtered_pids, task->pid)) ||
(filtered_no_pids &&
trace_find_filtered_pid(filtered_no_pids, task->pid));
}
/**
* trace_filter_add_remove_task - Add or remove a task from a pid_list
* @pid_list: The list to modify
* @self: The current task for fork or NULL for exit
* @task: The task to add or remove
*
* If adding a task, if @self is defined, the task is only added if @self
* is also included in @pid_list. This happens on fork and tasks should
* only be added when the parent is listed. If @self is NULL, then the
* @task pid will be removed from the list, which would happen on exit
* of a task.
*/
void trace_filter_add_remove_task(struct trace_pid_list *pid_list,
struct task_struct *self,
struct task_struct *task)
{
if (!pid_list)
return;
/* For forks, we only add if the forking task is listed */
if (self) {
if (!trace_find_filtered_pid(pid_list, self->pid))
return;
}
/* "self" is set for forks, and NULL for exits */
if (self)
trace_pid_list_set(pid_list, task->pid);
else
trace_pid_list_clear(pid_list, task->pid);
}
/**
* trace_pid_next - Used for seq_file to get to the next pid of a pid_list
* @pid_list: The pid list to show
* @v: The last pid that was shown (+1 the actual pid to let zero be displayed)
* @pos: The position of the file
*
* This is used by the seq_file "next" operation to iterate the pids
* listed in a trace_pid_list structure.
*
* Returns the pid+1 as we want to display pid of zero, but NULL would
* stop the iteration.
*/
void *trace_pid_next(struct trace_pid_list *pid_list, void *v, loff_t *pos)
{
long pid = (unsigned long)v;
unsigned int next;
(*pos)++;
/* pid already is +1 of the actual previous bit */
if (trace_pid_list_next(pid_list, pid, &next) < 0)
return NULL;
pid = next;
/* Return pid + 1 to allow zero to be represented */
return (void *)(pid + 1);
}
/**
* trace_pid_start - Used for seq_file to start reading pid lists
* @pid_list: The pid list to show
* @pos: The position of the file
*
* This is used by seq_file "start" operation to start the iteration
* of listing pids.
*
* Returns the pid+1 as we want to display pid of zero, but NULL would
* stop the iteration.
*/
void *trace_pid_start(struct trace_pid_list *pid_list, loff_t *pos)
{
unsigned long pid;
unsigned int first;
loff_t l = 0;
if (trace_pid_list_first(pid_list, &first) < 0)
return NULL;
pid = first;
/* Return pid + 1 so that zero can be the exit value */
for (pid++; pid && l < *pos;
pid = (unsigned long)trace_pid_next(pid_list, (void *)pid, &l))
;
return (void *)pid;
}
/**
* trace_pid_show - show the current pid in seq_file processing
* @m: The seq_file structure to write into
* @v: A void pointer of the pid (+1) value to display
*
* Can be directly used by seq_file operations to display the current
* pid value.
*/
int trace_pid_show(struct seq_file *m, void *v)
{
unsigned long pid = (unsigned long)v - 1;
seq_printf(m, "%lu\n", pid);
return 0;
}
/* 128 should be much more than enough */
#define PID_BUF_SIZE 127
int trace_pid_write(struct trace_pid_list *filtered_pids,
struct trace_pid_list **new_pid_list,
const char __user *ubuf, size_t cnt)
{
struct trace_pid_list *pid_list;
struct trace_parser parser;
unsigned long val;
int nr_pids = 0;
ssize_t read = 0;
ssize_t ret;
loff_t pos;
pid_t pid;
if (trace_parser_get_init(&parser, PID_BUF_SIZE + 1))
return -ENOMEM;
/*
* Always recreate a new array. The write is an all or nothing
* operation. Always create a new array when adding new pids by
* the user. If the operation fails, then the current list is
* not modified.
*/
pid_list = trace_pid_list_alloc();
if (!pid_list) {
trace_parser_put(&parser);
return -ENOMEM;
}
if (filtered_pids) {
/* copy the current bits to the new max */
ret = trace_pid_list_first(filtered_pids, &pid);
while (!ret) {
ret = trace_pid_list_set(pid_list, pid);
if (ret < 0)
goto out;
ret = trace_pid_list_next(filtered_pids, pid + 1, &pid);
nr_pids++;
}
}
ret = 0;
while (cnt > 0) {
pos = 0;
ret = trace_get_user(&parser, ubuf, cnt, &pos);
if (ret < 0)
break;
read += ret;
ubuf += ret;
cnt -= ret;
if (!trace_parser_loaded(&parser))
break;
ret = -EINVAL;
if (kstrtoul(parser.buffer, 0, &val))
break;
pid = (pid_t)val;
if (trace_pid_list_set(pid_list, pid) < 0) {
ret = -1;
break;
}
nr_pids++;
trace_parser_clear(&parser);
ret = 0;
}
out:
trace_parser_put(&parser);
if (ret < 0) {
trace_pid_list_free(pid_list);
return ret;
}
if (!nr_pids) {
/* Cleared the list of pids */
trace_pid_list_free(pid_list);
pid_list = NULL;
}
*new_pid_list = pid_list;
return read;
}