CID 1341620 Fix a small memory leak
CID 1341630 Though this is technically a false positive, rearrange the
code for clarity.
CID 1341635 Eliminate dead code
CID 1368663 Fix a double mutex unlock in the error path
Also:
* Use sig_atomic_t for variables accessed from signal handlers
* Don't conditionalize free(3) on its argument being non-null
Reported by: Coverity
CID: 1341620 1341630 1341635 1368663
Reviewed by: ken
MFC after: 4 weeks
Sponsored by: Spectra Logic Corp
Differential Revision: https://reviews.freebsd.org/D9237
5b1696c73f