[LU-3683] KUC code treats 0 as an invalid file descriptor

• Type: Bug
• Resolution: Fixed
• Priority: Critical
• Fix Version/s: Lustre 2.5.0
• Affects Version/s: Lustre 2.5.0
• Labels: HSM changelog kuc
• Severity: 3
• Assignee: Bob Glossman (Inactive)
• Reporter: John Hammond

Description

struct lustre_kernelcomm uses __u32 for lk_wfd and lk_rfd. But these are initialized using the file descriptors returned by pipe(). Hence 0 is a possible valid value. On cleanup we have tests like

        if (link->lk_wfd > 0)
                close(link->lk_wfd);

and in llapi_changelog_start() we have

        close(cp->kuc.lk_wfd);
        cp->kuc.lk_wfd = 0;

Use of 0 should be replaced with -1U and tests should compare against this value.