diff options
| -rw-r--r-- | include/linux/pid.h | 1 | ||||
| -rw-r--r-- | kernel/pid.c | 36 | ||||
| -rw-r--r-- | mm/madvise.c | 15 | ||||
| -rw-r--r-- | mm/oom_kill.c | 15 |
4 files changed, 43 insertions, 24 deletions
diff --git a/include/linux/pid.h b/include/linux/pid.h index af308e15f174..343abf22092e 100644 --- a/include/linux/pid.h +++ b/include/linux/pid.h @@ -78,6 +78,7 @@ struct file; extern struct pid *pidfd_pid(const struct file *file); struct pid *pidfd_get_pid(unsigned int fd, unsigned int *flags); +struct task_struct *pidfd_get_task(int pidfd, unsigned int *flags); int pidfd_create(struct pid *pid, unsigned int flags); static inline struct pid *get_pid(struct pid *pid) diff --git a/kernel/pid.c b/kernel/pid.c index efe87db44683..2fc0a16ec77b 100644 --- a/kernel/pid.c +++ b/kernel/pid.c @@ -540,6 +540,42 @@ struct pid *pidfd_get_pid(unsigned int fd, unsigned int *flags) } /** + * pidfd_get_task() - Get the task associated with a pidfd + * + * @pidfd: pidfd for which to get the task + * @flags: flags associated with this pidfd + * + * Return the task associated with @pidfd. The function takes a reference on + * the returned task. The caller is responsible for releasing that reference. + * + * Currently, the process identified by @pidfd is always a thread-group leader. + * This restriction currently exists for all aspects of pidfds including pidfd + * creation (CLONE_PIDFD cannot be used with CLONE_THREAD) and pidfd polling + * (only supports thread group leaders). + * + * Return: On success, the task_struct associated with the pidfd. + * On error, a negative errno number will be returned. + */ +struct task_struct *pidfd_get_task(int pidfd, unsigned int *flags) +{ + unsigned int f_flags; + struct pid *pid; + struct task_struct *task; + + pid = pidfd_get_pid(pidfd, &f_flags); + if (IS_ERR(pid)) + return ERR_CAST(pid); + + task = get_pid_task(pid, PIDTYPE_TGID); + put_pid(pid); + if (!task) + return ERR_PTR(-ESRCH); + + *flags = f_flags; + return task; +} + +/** * pidfd_create() - Create a new pid file descriptor. * * @pid: struct pid that the pidfd will reference diff --git a/mm/madvise.c b/mm/madvise.c index 0734db8d53a7..8c927202bbe6 100644 --- a/mm/madvise.c +++ b/mm/madvise.c @@ -1235,7 +1235,6 @@ SYSCALL_DEFINE5(process_madvise, int, pidfd, const struct iovec __user *, vec, struct iovec iovstack[UIO_FASTIOV], iovec; struct iovec *iov = iovstack; struct iov_iter iter; - struct pid *pid; struct task_struct *task; struct mm_struct *mm; size_t total_len; @@ -1250,18 +1249,12 @@ SYSCALL_DEFINE5(process_madvise, int, pidfd, const struct iovec __user *, vec, if (ret < 0) goto out; - pid = pidfd_get_pid(pidfd, &f_flags); - if (IS_ERR(pid)) { - ret = PTR_ERR(pid); + task = pidfd_get_task(pidfd, &f_flags); + if (IS_ERR(task)) { + ret = PTR_ERR(task); goto free_iov; } - task = get_pid_task(pid, PIDTYPE_PID); - if (!task) { - ret = -ESRCH; - goto put_pid; - } - if (!process_madvise_behavior_valid(behavior)) { ret = -EINVAL; goto release_task; @@ -1301,8 +1294,6 @@ release_mm: mmput(mm); release_task: put_task_struct(task); -put_pid: - put_pid(pid); free_iov: kfree(iov); out: diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 195b3661da3d..1ddabefcfb5a 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -1150,21 +1150,14 @@ SYSCALL_DEFINE2(process_mrelease, int, pidfd, unsigned int, flags) struct task_struct *p; unsigned int f_flags; bool reap = false; - struct pid *pid; long ret = 0; if (flags) return -EINVAL; - pid = pidfd_get_pid(pidfd, &f_flags); - if (IS_ERR(pid)) - return PTR_ERR(pid); - - task = get_pid_task(pid, PIDTYPE_TGID); - if (!task) { - ret = -ESRCH; - goto put_pid; - } + task = pidfd_get_task(pidfd, &f_flags); + if (IS_ERR(task)) + return PTR_ERR(task); /* * Make sure to choose a thread which still has a reference to mm @@ -1204,8 +1197,6 @@ drop_mm: mmput(mm); put_task: put_task_struct(task); -put_pid: - put_pid(pid); return ret; #else return -ENOSYS; |