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kernel: throne_tracker: offload to kthread (tiann[#2632](https://github.com/SukiSU-Ultra/SukiSU-Ultra/issues/2632))

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Run throne_tracker() in kthread instead of blocking the caller.
Prevents full lockup during installation and removing the manager.

First run remains synchronous for compatibility purposes (FDE, FBEv1, FBEv2)

Features:
- run track_throne() in a kthread after the first synchronous run
- prevent duplicate thread creation with a single-instance check
- spinlock-on-d_lock based polling adressing possible race conditions.

Race conditions adressed
- single instance kthread lock, smp_mb()
- is_manager_apk, apk, spinlock-on-d_lock based polling

This is a squash of:
https://github.com/tiann/KernelSU/pull/2632

Rebased on top of
https://github.com/tiann/KernelSU/pull/2757

Original skeleton based on:
`kernelsu: move throne_tracker() to kthread`
`kernelsu: check locking before accessing files and dirs during searching manager`
`kernelsu: look for manager UID in /data/system/packages.list, not /data/system/packages.list.tmp`
0b05e927...8783badd

Co-Authored-By: backslashxx <118538522+backslashxx@users.noreply.github.com>
Co-Authored-By: Yaroslav Zviezda <10716792+acroreiser@users.noreply.github.com>
Signed-off-by: backslashxx <118538522+backslashxx@users.noreply.github.com>
This commit is contained in:
ShirkNeko
2025-09-14 11:53:33 +08:00
parent 4c3bdcd016
commit debd7d5a01
5 changed files with 132 additions and 9 deletions
Download Patch File Download Diff File Expand all files Collapse all files

45
kernel/throne_tracker.c
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@@ -11,13 +11,19 @@
#include "allowlist.h"
#include "klog.h" // IWYU pragma: keep
#include "ksu.h"
#include "ksud.h"
#include "manager.h"
#include "throne_tracker.h"
#include "kernel_compat.h"
#include "dynamic_manager.h"
#include <linux/kthread.h>
#include <linux/sched.h>
uid_t ksu_manager_uid = KSU_INVALID_UID;
static struct task_struct *throne_thread;
#define USER_DATA_BASE_PATH "/data/user_de"
#define MAX_SUPPORTED_USERS 32 // Supports up to 32 users
#define DATA_PATH_LEN 384 // 384 is enough for /data/app/<package>/base.apk and /data/user_de/{userid}/<package>
@@ -526,7 +532,7 @@ void search_manager(const char *path, int depth, struct list_head *uid_data)
struct file *file;
if (!stop) {
file = ksu_filp_open_compat(pos->dirpath, O_RDONLY | O_NOFOLLOW, 0);
file = ksu_filp_open_compat(pos->dirpath, O_RDONLY | O_NOFOLLOW | O_DIRECTORY, 0);
if (IS_ERR(file)) {
pr_err("Failed to open directory: %s, err: %ld\n", pos->dirpath, PTR_ERR(file));
goto skip_iterate;
@@ -584,7 +590,7 @@ static bool is_uid_exist(uid_t uid, char *package, void *data)
return exist;
}
void track_throne(void)
static void track_throne_function(void)
{
struct list_head uid_list;
INIT_LIST_HEAD(&uid_list);
@@ -652,6 +658,41 @@ out:
}
}
static int throne_tracker_thread(void *data)
{
pr_info("%s: pid: %d started\n", __func__, current->pid);
// for the kthread, we need to escape to root
// since it does not inherit the caller's context.
// this runs as root but without the capabilities, so call it with false
escape_to_root(false);
track_throne_function();
throne_thread = NULL;
smp_mb();
pr_info("%s: pid: %d exit!\n", __func__, current->pid);
return 0;
}
void track_throne(void)
{
static bool throne_tracker_first_run __read_mostly = true;
if (unlikely(throne_tracker_first_run)) {
track_throne_function();
throne_tracker_first_run = false;
return;
}
smp_mb();
if (throne_thread != NULL) // single instance lock
return;
throne_thread = kthread_run(throne_tracker_thread, NULL, "throne_tracker");
if (IS_ERR(throne_thread)) {
throne_thread = NULL;
return;
}
}
void ksu_throne_tracker_init(void)
{
// nothing to do