On Wed, Sep 30, 2020 at 07:42:42PM +0300, Jouni Roivas wrote:
> Do not report failure on zero sized writes, and handle them as no-op.
>
> There's issues for example in case of writev() when there's iovec
> containing zero buffer as a first one. It's expected writev() on below
> example to successfully perform the write to specified writable cgroup
> file expecting integer value, and to return 2. For now it's returning
> value -1, and skipping the write:
>
> int writetest(int fd) {
> const char *buf1 = "";
> const char *buf2 = "1\n";
> struct iovec iov[2] = {
> { .iov_base = (void*)buf1, .iov_len = 0 },
> { .iov_base = (void*)buf2, .iov_len = 2 }
> };
> return writev(fd, iov, 2);
> }
>
> This patch fixes the issue by checking if there's nothing to write,
> and handling the write as no-op by just returning 0.
Applied to cgroup/for-5.10.
Thanks.
--
tejun
