Creates {reader,writer,kfree}_tasks files in the "rcuscale" debugfs
folder. Each line contains one kernel thread PID.
This provides a more robust way for external performance analysis tools
to attach to kernel threads than using pgrep.
Signed-off-by: Yuzhuo Jing <yuzhuo@xxxxxxxxxx>
---
kernel/rcu/rcuscale.c | 124 ++++++++++++++++++++++++++++++++++++++++++
1 file changed, 124 insertions(+)
diff --git a/kernel/rcu/rcuscale.c b/kernel/rcu/rcuscale.c
index ad10b42be6fc..7c88d461ed2c 100644
--- a/kernel/rcu/rcuscale.c
+++ b/kernel/rcu/rcuscale.c
@@ -143,6 +143,9 @@ static unsigned long b_rcu_gp_test_finished;
static struct dentry *debugfs_dir;
static struct dentry *debugfs_writer_durations;
+static struct dentry *debugfs_reader_tasks;
+static struct dentry *debugfs_writer_tasks;
+static struct dentry *debugfs_kfree_tasks;
#define MAX_MEAS 10000
#define MIN_MEAS 100
@@ -1009,6 +1012,112 @@ static const struct file_operations writer_durations_fops = {
.release = seq_release,
};
+/*
+ * Generic seq_file private data for tasks walkthrough.
+ */
+struct debugfs_pid_info {
+ int ntasks;
+ struct task_struct **tasks;
+};
+
+/*
+ * Generic seq_file pos to pointer conversion function, using private data
+ * of type debugfs_pid_info, and ensure it is within bound.
+ */
+static void *debugfs_pid_start(struct seq_file *m, loff_t *pos)
+{
+ loff_t worker = *pos;
+ struct debugfs_pid_info *info = m->private;
+
+ if (worker < 0 || worker >= info->ntasks)
+ return NULL;
+
+ return info->tasks[worker];
+}
+
+static void *debugfs_pid_next(struct seq_file *m, void *v, loff_t *pos)
+{
+ (*pos)++;
+ return debugfs_pid_start(m, pos);
+}
+
+/*
+ * Each line of the file contains one PID from the selected kernel threads.
+ */
+static int debugfs_pid_show(struct seq_file *m, void *v)
+{
+ seq_printf(m, "%d\n", ((struct task_struct *)v)->pid);
+ return 0;
+}
+
+static void debugfs_pid_stop(struct seq_file *m, void *v)
+{
+}
+
+static const struct seq_operations debugfs_pid_fops = {
+ .start = debugfs_pid_start,
+ .next = debugfs_pid_next,
+ .stop = debugfs_pid_stop,
+ .show = debugfs_pid_show
+};
+
+/*
+ * Generic seq_file creation function that sets private data of type
+ * debugfs_pid_info.
+ */
+static int debugfs_pid_open_info(struct inode *inode, struct file *file,
+ int ntasks, struct task_struct **tasks)
+{
+ struct debugfs_pid_info *info =
+ __seq_open_private(file, &debugfs_pid_fops, sizeof(*info));
+ if (!info)
+ return -ENOMEM;
+
+ info->ntasks = ntasks;
+ info->tasks = tasks;
+
+ return 0;
+}
+
+static int debugfs_pid_open_reader(struct inode *inode, struct file *file)
+{
+ return debugfs_pid_open_info(inode, file, nrealreaders, reader_tasks);
+}
+
+static int debugfs_pid_open_writer(struct inode *inode, struct file *file)
+{
+ return debugfs_pid_open_info(inode, file, nrealwriters, writer_tasks);
+}
+
+static int debugfs_pid_open_kfree(struct inode *inode, struct file *file)
+{
+ return debugfs_pid_open_info(inode, file, kfree_nrealthreads, kfree_reader_tasks);
+}
+
+static const struct file_operations readers_fops = {
+ .owner = THIS_MODULE,
+ .open = debugfs_pid_open_reader,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = seq_release,
+};
+
+static const struct file_operations writers_fops = {
+ .owner = THIS_MODULE,
+ .open = debugfs_pid_open_writer,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = seq_release,
+};
+
+static const struct file_operations kfrees_fops = {
+ .owner = THIS_MODULE,
+ .open = debugfs_pid_open_kfree,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = seq_release,
+};
+
/*
* Create an rcuscale directory exposing run states and results.
*/
@@ -1032,6 +1141,18 @@ static int register_debugfs(void)
debugfs_dir, NULL, &writer_durations_fops))
goto fail;
+ if (try_create_file(debugfs_reader_tasks, "reader_tasks", 0444,
+ debugfs_dir, NULL, &readers_fops))
+ goto fail;
+
+ if (try_create_file(debugfs_writer_tasks, "writer_tasks", 0444,
+ debugfs_dir, NULL, &writers_fops))
+ goto fail;
+
+ if (try_create_file(debugfs_kfree_tasks, "kfree_tasks", 0444,
+ debugfs_dir, NULL, &kfrees_fops))
+ goto fail;
+
return 0;
fail:
pr_err("rcu-scale: Failed to create debugfs file.");
@@ -1052,6 +1173,9 @@ do { \
} while (0)
try_remove(debugfs_writer_durations);
+ try_remove(debugfs_reader_tasks);
+ try_remove(debugfs_writer_tasks);
+ try_remove(debugfs_kfree_tasks);
/* Remove directory after files. */
try_remove(debugfs_dir);
--
2.50.1.552.g942d659e1b-goog
