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    Subject[PATCH -1/24] exec: Don't open code get_close_on_exec

    Al Viro pointed out that using the phrase "close_on_exec(fd,
    rcu_dereference_raw(current->files->fdt))" instead of wrapping it in
    rcu_read_lock(), rcu_read_unlock() is a very questionable
    optimization[1].

    Once wrapped with rcu_read_lock()/rcu_read_unlock() that phrase
    becomes equivalent the helper function get_close_on_exec so
    simplify the code and make it more robust by simply using
    get_close_on_exec.

    [1] https://lkml.kernel.org/r/20201207222214.GA4115853@ZenIV.linux.org.uk
    Suggested-by: Al Viro <viro@ftp.linux.org.uk>
    Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
    ---

    I aim to rebase my exec branch and apply this tomorrow.

    fs/exec.c | 3 +--
    1 file changed, 1 insertion(+), 2 deletions(-)

    diff --git a/fs/exec.c b/fs/exec.c
    index 547a2390baf5..9aabf6e8c904 100644
    --- a/fs/exec.c
    +++ b/fs/exec.c
    @@ -1808,8 +1808,7 @@ static int bprm_execve(struct linux_binprm *bprm,
    * inaccessible after exec. Relies on having exclusive access to
    * current->files (due to unshare_files above).
    */
    - if (bprm->fdpath &&
    - close_on_exec(fd, rcu_dereference_raw(current->files->fdt)))
    + if (bprm->fdpath && get_close_on_exec(fd))
    bprm->interp_flags |= BINPRM_FLAGS_PATH_INACCESSIBLE;

    /* Set the unchanging part of bprm->cred */
    --
    2.20.1
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