tracing: Move pid filtering into trace_pid.c

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>

Author: rostedt

kernel/trace/Makefile

@@ -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

kernel/trace/trace.c

@@ -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;