DPDK and signal safety

[Stephen Hemminger]

The recent CVE in OpenSSH related signal safety piqued my interest in
any possible issues in DPDK.

While reviewing:
   - The use of SIGBUS in linux/eal_dev is problematic.
     It is using not signal safe routines such as rte_spinlock and logging.
     This was done as part of hotplug support.

   - The use of SIGBUS in eal_memmalloc is ok, since it is limited in scope
     and only while alloc_seg()

   - Tap uses rt sig and is sigsafe since only updating flag.

   - FPGA driver is catching SIGINT in update_flash.
     it calls dev_info which is not sig safe.
     SIGINT is not enough here, what about SIGTERM or SIGHUP?
     And overriding application signals does not appear to be documented.