This refactors the fork helpers so they can be easily modified in the next patches. The patch just passes in the parent task_struct and moves the cgroup threadgroup rwsem grab and release into the helpers. The don't need to be directly exposed in fork.c. Cc: Tejun Heo <tj@xxxxxxxxxx> Cc: Johannes Weiner <hannes@xxxxxxxxxxx> Cc: Li Zefan <lizefan@xxxxxxxxxx> Cc: cgroups@xxxxxxxxxxxxxxx Signed-off-by: Christian Brauner <christian.brauner@xxxxxxxxxx> --- /* v1 */ patch not present /* v2 */ patch not present /* v3 */ Link: https://lore.kernel.org/r/20200117002143.15559-4-christian.brauner@xxxxxxxxxx patch introduced - Tejun Heo <tj@xxxxxxxxxx>: - split into separate commmit /* v4 */ unchanged --- include/linux/cgroup.h | 18 +++++++++----- kernel/cgroup/cgroup.c | 56 ++++++++++++++++++++++++++---------------- kernel/fork.c | 12 +++------ 3 files changed, 51 insertions(+), 35 deletions(-) diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index d7ddebd0cdec..5349465bfac1 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -121,9 +121,12 @@ int proc_cgroup_show(struct seq_file *m, struct pid_namespace *ns, struct pid *pid, struct task_struct *tsk); void cgroup_fork(struct task_struct *p); -extern int cgroup_can_fork(struct task_struct *p); -extern void cgroup_cancel_fork(struct task_struct *p); -extern void cgroup_post_fork(struct task_struct *p); +extern int cgroup_can_fork(struct task_struct *parent, + struct task_struct *child); +extern void cgroup_cancel_fork(struct task_struct *parent, + struct task_struct *child); +extern void cgroup_post_fork(struct task_struct *parent, + struct task_struct *child); void cgroup_exit(struct task_struct *p); void cgroup_release(struct task_struct *p); void cgroup_free(struct task_struct *p); @@ -707,9 +710,12 @@ static inline int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry) { return -EINVAL; } static inline void cgroup_fork(struct task_struct *p) {} -static inline int cgroup_can_fork(struct task_struct *p) { return 0; } -static inline void cgroup_cancel_fork(struct task_struct *p) {} -static inline void cgroup_post_fork(struct task_struct *p) {} +static inline int cgroup_can_fork(struct task_struct *parent, + struct task_struct *child) { return 0; } +static inline void cgroup_cancel_fork(struct task_struct *parent, + struct task_struct *child) {}; +static inline void cgroup_post_fork(struct task_struct *parent, + struct task_struct *child) {}; static inline void cgroup_exit(struct task_struct *p) {} static inline void cgroup_release(struct task_struct *p) {} static inline void cgroup_free(struct task_struct *p) {} diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index f05efc2677c8..49d8cf087e10 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -5902,17 +5902,22 @@ static struct cgroup *cgroup_get_from_file(struct file *f) /** * cgroup_can_fork - called on a new task before the process is exposed - * @child: the task in question. + * @parent: the parent process of @child + * @child: the child process of @parent + * @kargs: the arguments passed to create the child process * - * This calls the subsystem can_fork() callbacks. If the can_fork() callback - * returns an error, the fork aborts with that error code. This allows for - * a cgroup subsystem to conditionally allow or deny new forks. + * This calls the subsystem can_fork() callbacks. If the cgroup_can_fork() + * callback returns an error, the fork aborts with that error code. This + * allows for a cgroup subsystem to conditionally allow or deny new forks. */ -int cgroup_can_fork(struct task_struct *child) +int cgroup_can_fork(struct task_struct *parent, struct task_struct *child) + __acquires(&cgroup_threadgroup_rwsem) __releases(&cgroup_threadgroup_rwsem) { struct cgroup_subsys *ss; int i, j, ret; + cgroup_threadgroup_change_begin(parent); + do_each_subsys_mask(ss, i, have_canfork_callback) { ret = ss->can_fork(child); if (ret) @@ -5929,17 +5934,22 @@ int cgroup_can_fork(struct task_struct *child) ss->cancel_fork(child); } + cgroup_threadgroup_change_end(parent); + return ret; } /** - * cgroup_cancel_fork - called if a fork failed after cgroup_can_fork() - * @child: the task in question - * - * This calls the cancel_fork() callbacks if a fork failed *after* - * cgroup_can_fork() succeded. - */ -void cgroup_cancel_fork(struct task_struct *child) + * cgroup_cancel_fork - called if a fork failed after cgroup_can_fork() + * @parent: the parent process of @child + * @child: the child process of @parent + * @kargs: the arguments passed to create the child process + * + * This calls the cancel_fork() callbacks if a fork failed *after* + * cgroup_can_fork() succeded. + */ +void cgroup_cancel_fork(struct task_struct *parent, struct task_struct *child) + __releases(&cgroup_threadgroup_rwsem) { struct cgroup_subsys *ss; int i; @@ -5947,19 +5957,21 @@ void cgroup_cancel_fork(struct task_struct *child) for_each_subsys(ss, i) if (ss->cancel_fork) ss->cancel_fork(child); + + cgroup_threadgroup_change_end(parent); } /** - * cgroup_post_fork - called on a new task after adding it to the task list - * @child: the task in question - * - * Adds the task to the list running through its css_set if necessary and - * call the subsystem fork() callbacks. Has to be after the task is - * visible on the task list in case we race with the first call to - * cgroup_task_iter_start() - to guarantee that the new task ends up on its - * list. + * cgroup_post_fork - finalize cgroup setup for the child process + * @parent: the parent process of @child + * @child: the child process of @parent + * @kargs: the arguments passed to create the child process + * + * Attach the child process to its css_set calling the subsystem fork() + * callbacks. */ -void cgroup_post_fork(struct task_struct *child) +void cgroup_post_fork(struct task_struct *parent, struct task_struct *child) + __releases(&cgroup_threadgroup_rwsem) { struct cgroup_subsys *ss; struct css_set *cset; @@ -6002,6 +6014,8 @@ void cgroup_post_fork(struct task_struct *child) do_each_subsys_mask(ss, i, have_fork_callback) { ss->fork(child); } while_each_subsys_mask(); + + cgroup_threadgroup_change_end(parent); } /** diff --git a/kernel/fork.c b/kernel/fork.c index 080809560072..c76758dbd594 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -2165,16 +2165,15 @@ static __latent_entropy struct task_struct *copy_process( INIT_LIST_HEAD(&p->thread_group); p->task_works = NULL; - cgroup_threadgroup_change_begin(current); /* * Ensure that the cgroup subsystem policies allow the new process to be * forked. It should be noted the the new process's css_set can be changed * between here and cgroup_post_fork() if an organisation operation is in * progress. */ - retval = cgroup_can_fork(p); + retval = cgroup_can_fork(current, p); if (retval) - goto bad_fork_cgroup_threadgroup_change_end; + goto bad_fork_put_pidfd; /* * From this point on we must avoid any synchronous user-space @@ -2279,8 +2278,7 @@ static __latent_entropy struct task_struct *copy_process( write_unlock_irq(&tasklist_lock); proc_fork_connector(p); - cgroup_post_fork(p); - cgroup_threadgroup_change_end(current); + cgroup_post_fork(current, p); perf_event_fork(p); trace_task_newtask(p, clone_flags); @@ -2291,9 +2289,7 @@ static __latent_entropy struct task_struct *copy_process( bad_fork_cancel_cgroup: spin_unlock(¤t->sighand->siglock); write_unlock_irq(&tasklist_lock); - cgroup_cancel_fork(p); -bad_fork_cgroup_threadgroup_change_end: - cgroup_threadgroup_change_end(current); + cgroup_cancel_fork(current, p); bad_fork_put_pidfd: if (clone_flags & CLONE_PIDFD) { fput(pidfile); -- 2.25.0
