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    SubjectRe: [PATCH] Add cloexec information to fdinfo
    (2011/06/10 12:55), drepper@akkadia.org wrote:
    > There is one piece of information about a file descriptor which is
    > currently not visible from the outside: the close-on-exec flag. The
    > /proc/PID/fdinfo/* files have the mode information but this is
    > missing. Is the following patch acceptable?
    >
    > What I don't know is whether the RCU locking is needed given that
    > real locks are taken. Someone with more knowledge could just
    > remove those two lines.
    >
    >
    > Signed-off-by: Ulrich Drepper <drepper@gmail.com>
    >
    > base.c | 17 ++++++++++++++---
    > 1 file changed, 14 insertions(+), 3 deletions(-)
    >
    > diff --git a/fs/proc/base.c b/fs/proc/base.c
    > index 14def99..bda3651 100644
    > --- a/fs/proc/base.c
    > +++ b/fs/proc/base.c
    > @@ -1924,12 +1924,23 @@ static int proc_fd_info(struct inode *inode, struct path *path, char *info)
    > *path = file->f_path;
    > path_get(&file->f_path);
    > }
    > - if (info)
    > + if (info) {
    > + int cloexec;
    > + struct fdtable *fdt;
    > +
    > + rcu_read_lock();
    > + fdt = files_fdtable(files);
    > + cloexec = FD_ISSET(fd, fdt->close_on_exec);
    > + rcu_read_unlock();
    > +
    > snprintf(info, PROC_FDINFO_MAX,
    > "pos:\t%lli\n"
    > - "flags:\t0%o\n",
    > + "flags:\t0%o\n"
    > + "cloexec: %d\n",
    > (long long) file->f_pos,
    > - file->f_flags);
    > + file->f_flags,
    > + cloexec);
    > + }
    > spin_unlock(&files->file_lock);
    > put_files_struct(files);
    > return 0;

    I think this is correct and useful. However I don't know fdtable life cycle detail.
    cc to linux-fsdevel.



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