ich777/linux_media
1
0
Fork 0
mirror of https://github.com/tbsdtv/linux_media.git synced 2025-07-23 12:43:29 +02:00
Code Issues Packages Projects Releases Wiki Activity

Merge branch 'exec-update-lock-for-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace

Browse Source 
Pull exec-update-lock update from Eric Biederman:
 "The key point of this is to transform exec_update_mutex into a
  rw_semaphore so readers can be separated from writers.

  This makes it easier to understand what the holders of the lock are
  doing, and makes it harder to contend or deadlock on the lock.

  The real deadlock fix wound up in perf_event_open"

* 'exec-update-lock-for-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
  exec: Transform exec_update_mutex into a rw_semaphore
This commit is contained in:
Linus Torvalds
2020-12-15 19:36:48 -08:00
parent faf145d6f3 f7cfd871ae
commit d01e7f10da
8 changed files with 44 additions and 43 deletions
Download Patch File Download Diff File Expand all files Collapse all files

30
kernel/kcmp.c
View File

@@ -70,25 +70,25 @@ get_file_raw_ptr(struct task_struct *task, unsigned int idx)
return file;
}
static void kcmp_unlock(struct mutex *m1, struct mutex *m2)
static void kcmp_unlock(struct rw_semaphore *l1, struct rw_semaphore *l2)
{
if (likely(m2 != m1))
mutex_unlock(m2);
mutex_unlock(m1);
if (likely(l2 != l1))
up_read(l2);
up_read(l1);
}
static int kcmp_lock(struct mutex *m1, struct mutex *m2)
static int kcmp_lock(struct rw_semaphore *l1, struct rw_semaphore *l2)
{
int err;
if (m2 > m1)
swap(m1, m2);
if (l2 > l1)
swap(l1, l2);
err = mutex_lock_killable(m1);
if (!err && likely(m1 != m2)) {
err = mutex_lock_killable_nested(m2, SINGLE_DEPTH_NESTING);
err = down_read_killable(l1);
if (!err && likely(l1 != l2)) {
err = down_read_killable_nested(l2, SINGLE_DEPTH_NESTING);
if (err)
mutex_unlock(m1);
up_read(l1);
}
return err;
@@ -156,8 +156,8 @@ SYSCALL_DEFINE5(kcmp, pid_t, pid1, pid_t, pid2, int, type,
/*
* One should have enough rights to inspect task details.
*/
ret = kcmp_lock(&task1->signal->exec_update_mutex,
&task2->signal->exec_update_mutex);
ret = kcmp_lock(&task1->signal->exec_update_lock,
&task2->signal->exec_update_lock);
if (ret)
goto err;
if (!ptrace_may_access(task1, PTRACE_MODE_READ_REALCREDS) ||
@@ -212,8 +212,8 @@ SYSCALL_DEFINE5(kcmp, pid_t, pid1, pid_t, pid2, int, type,
}
err_unlock:
kcmp_unlock(&task1->signal->exec_update_mutex,
&task2->signal->exec_update_mutex);
kcmp_unlock(&task1->signal->exec_update_lock,
&task2->signal->exec_update_lock);
err:
put_task_struct(task1);
put_task_struct(task2);