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| author | Eric W. Biederman <ebiederm@xmission.com> | 2020-11-20 17:14:21 -0600 |
|---|---|---|
| committer | Eric W. Biederman <ebiederm@xmission.com> | 2020-12-10 12:39:40 -0600 |
| commit | f43c283a89a7dc531a47d4b1e001503cf3dc3234 (patch) | |
| tree | 4cd07b236726827c958bfe2e67bf9f2dd2194fd3 /kernel/kcmp.c | |
| parent | 950db38ff2c01b7aabbd7ab4a50b7992750fa63d (diff) | |
| download | linux-f43c283a89a7dc531a47d4b1e001503cf3dc3234.tar.gz linux-f43c283a89a7dc531a47d4b1e001503cf3dc3234.tar.bz2 linux-f43c283a89a7dc531a47d4b1e001503cf3dc3234.zip | |
kcmp: In kcmp_epoll_target use fget_task
Use the helper fget_task and simplify the code.
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.
Suggested-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Cyrill Gorcunov <gorcunov@gmail.com>
v1: https://lkml.kernel.org/r/20200817220425.9389-4-ebiederm@xmission.com
Link: https://lkml.kernel.org/r/20201120231441.29911-4-ebiederm@xmission.com
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Diffstat (limited to 'kernel/kcmp.c')
| -rw-r--r-- | kernel/kcmp.c | 20 |
1 files changed, 4 insertions, 16 deletions
diff --git a/kernel/kcmp.c b/kernel/kcmp.c index b3ff9288c6cc..87c48c0104ad 100644 --- a/kernel/kcmp.c +++ b/kernel/kcmp.c @@ -107,7 +107,6 @@ static int kcmp_epoll_target(struct task_struct *task1, { struct file *filp, *filp_epoll, *filp_tgt; struct kcmp_epoll_slot slot; - struct files_struct *files; if (copy_from_user(&slot, uslot, sizeof(slot))) return -EFAULT; @@ -116,23 +115,12 @@ static int kcmp_epoll_target(struct task_struct *task1, if (!filp) return -EBADF; - files = get_files_struct(task2); - if (!files) + filp_epoll = fget_task(task2, slot.efd); + if (!filp_epoll) return -EBADF; - spin_lock(&files->file_lock); - filp_epoll = fcheck_files(files, slot.efd); - if (filp_epoll) - get_file(filp_epoll); - else - filp_tgt = ERR_PTR(-EBADF); - spin_unlock(&files->file_lock); - put_files_struct(files); - - if (filp_epoll) { - filp_tgt = get_epoll_tfile_raw_ptr(filp_epoll, slot.tfd, slot.toff); - fput(filp_epoll); - } + filp_tgt = get_epoll_tfile_raw_ptr(filp_epoll, slot.tfd, slot.toff); + fput(filp_epoll); if (IS_ERR(filp_tgt)) return PTR_ERR(filp_tgt); |