diff options
| author | Eric W. Biederman <ebiederm@xmission.com> | 2020-11-21 00:14:22 +0100 |
|---|---|---|
| committer | Eric W. Biederman <ebiederm@xmission.com> | 2020-12-10 19:39:44 +0100 |
| commit | b48845af0152d790a54b8ab78cc2b7c07485fc98 (patch) | |
| tree | 1e2620306583bc904cb9bbf946f54d8f384d274d | |
| parent | kcmp: In kcmp_epoll_target use fget_task (diff) | |
| download | linux-b48845af0152d790a54b8ab78cc2b7c07485fc98.tar.xz linux-b48845af0152d790a54b8ab78cc2b7c07485fc98.zip | |
bpf: In bpf_task_fd_query use fget_task
Use the helper fget_task to simplify bpf_task_fd_query.
As well as simplifying the code this removes one unnecessary increment of
struct files_struct. This unnecessary increment of files_struct.count can
result in exec unnecessarily unsharing files_struct and breaking posix
locks, and it can result in fget_light having to fallback to fget reducing
performance.
This simplification comes from the observation that none of the
callers of get_files_struct actually need to call get_files_struct
that was made when discussing[1] exec and posix file locks.
[1] https://lkml.kernel.org/r/20180915160423.GA31461@redhat.com
Suggested-by: Oleg Nesterov <oleg@redhat.com>
v1: https://lkml.kernel.org/r/20200817220425.9389-5-ebiederm@xmission.com
Link: https://lkml.kernel.org/r/20201120231441.29911-5-ebiederm@xmission.com
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
| -rw-r--r-- | kernel/bpf/syscall.c | 20 |
1 files changed, 3 insertions, 17 deletions
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 8f50c9c19f1b..6d49c2e1634c 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -3878,7 +3878,6 @@ static int bpf_task_fd_query(const union bpf_attr *attr, pid_t pid = attr->task_fd_query.pid; u32 fd = attr->task_fd_query.fd; const struct perf_event *event; - struct files_struct *files; struct task_struct *task; struct file *file; int err; @@ -3896,23 +3895,11 @@ static int bpf_task_fd_query(const union bpf_attr *attr, if (!task) return -ENOENT; - files = get_files_struct(task); - put_task_struct(task); - if (!files) - return -ENOENT; - err = 0; - spin_lock(&files->file_lock); - file = fcheck_files(files, fd); + file = fget_task(task, fd); + put_task_struct(task); if (!file) - err = -EBADF; - else - get_file(file); - spin_unlock(&files->file_lock); - put_files_struct(files); - - if (err) - goto out; + return -EBADF; if (file->f_op == &bpf_link_fops) { struct bpf_link *link = file->private_data; @@ -3952,7 +3939,6 @@ out_not_supp: err = -ENOTSUPP; put_file: fput(file); -out: return err; } |