[Bug 220095] [scsi] sys/dev/dpt/dpt_scsi.c: a sleep-under-mutex bug in dpt_init

[Jia-Ju Bai]

The driver may sleep under a mutex, and the function call path in file 
"sys/dev/dpt/dpt_scsi.c" in FreeBSD 11.0 is:
dpt_init [line 1246: acquire the mutex]
   dptallocsgmap [line 1282]
     bus_dmamap_load(BUS_DMA_WAITOK) [line 323] --> may sleep

The possible fix of this bug is to set the last parameter in 
bus_dmamap_load to "BUS_DMA_NOWAIT".

This bug is found by a static analysis tool written by myself, and it is 
checked by my review of the FreeBSD code.

Thanks,
Jia-Ju Bai