[LU-4189] Strange code in mdc_changelog_send_thread

• Type: Bug
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.8.0
• Affects Version/s: Lustre 2.6.0
• Labels: easy patch
• Severity: 3
• Assignee: WC Triage
• Reporter: Oleg Drokin

Description

Playing with the stack tool, it uncovered this strange piece in mdc_changelog_send_thread:

        /* Send EOF no matter what our result */
        if ((kuch = changelog_kuc_hdr(cs->cs_buf, sizeof(*kuch),
                                      cs->cs_flags))) {
                kuch->kuc_msgtype = CL_EOF;
                libcfs_kkuc_msg_put(cs->cs_fp, kuch);
        }

Now, the thing is that changelog_kuc_hdr never returns NULL as we pass the pointer into it already and if it's zero, we'd totally die before even returning:

static struct kuc_hdr *changelog_kuc_hdr(char *buf, int len, int flags)
{
        struct kuc_hdr *lh = (struct kuc_hdr *)buf;

        LASSERT(len <= KUC_CHANGELOG_MSG_MAXSIZE);

        lh->kuc_magic = KUC_MAGIC;
        lh->kuc_transport = KUC_TRANSPORT_CHANGELOG;
        lh->kuc_flags = flags;
        lh->kuc_msgtype = CL_RECORD;
        lh->kuc_msglen = len;
        return lh;
}

So I guess weeither should do away with the if here and make for a more readable code, or actually insert some checks into changelog_kuc_hdr

Issue Links

• is related to: LU-2753 Tracking bug for static code analysis fixes.