[iscsi] Fix initiator kernel panic if target ctl(4) port is disabled

[afedorov]

Summary

If the target ctl(4) port is disabled using ctladm -p X -o off, the initiator creates incomplete sessions that lead to panic when calling 'ctladm islist'.

See detailed description: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=244792
And debug output: https://bz-attachments.freebsd.org/attachment.cgi?id=212383

[afedorov]

ping?

[jhb]

I think this looks right, but I think there are other places that also need the lock perhaps? I think there's at least one other place that does these two statements without holding the session lock when I looked.

[vmaffione]

+1
There are more places where the cv_signal(cs->xxx) is not called with the cs lock held. We could take the chance and fix them all.

[mav]

I think it is correct, except the same should be added also 48 lines lower.

But also looking on cfiscsi_ioctl_list() I am curios why (cs->cs_target == NULL) there is under #ifdef ICL_KERNEL_PROXY? Without one defined there is still a chance to crash before maintenance thread call cfiscsi_session_delete(). I think the ifdef should be removed.

[afedorov]

I will try to fix all the places.