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kcmp: In kcmp_epoll_target use fget_task
[ Upstream commit f43c283a89
]
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>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
parent
ba7aac19b4
commit
fe1722255e
1 changed files with 4 additions and 16 deletions
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@ -107,7 +107,6 @@ static int kcmp_epoll_target(struct task_struct *task1,
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{
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struct file *filp, *filp_epoll, *filp_tgt;
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struct kcmp_epoll_slot slot;
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struct files_struct *files;
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if (copy_from_user(&slot, uslot, sizeof(slot)))
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return -EFAULT;
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@ -116,23 +115,12 @@ static int kcmp_epoll_target(struct task_struct *task1,
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if (!filp)
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return -EBADF;
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files = get_files_struct(task2);
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if (!files)
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filp_epoll = fget_task(task2, slot.efd);
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if (!filp_epoll)
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return -EBADF;
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spin_lock(&files->file_lock);
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filp_epoll = fcheck_files(files, slot.efd);
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if (filp_epoll)
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get_file(filp_epoll);
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else
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filp_tgt = ERR_PTR(-EBADF);
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spin_unlock(&files->file_lock);
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put_files_struct(files);
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if (filp_epoll) {
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filp_tgt = get_epoll_tfile_raw_ptr(filp_epoll, slot.tfd, slot.toff);
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fput(filp_epoll);
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}
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filp_tgt = get_epoll_tfile_raw_ptr(filp_epoll, slot.tfd, slot.toff);
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fput(filp_epoll);
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if (IS_ERR(filp_tgt))
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return PTR_ERR(filp_tgt);
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