Bug 220095

Summary: [scsi] sys/dev/dpt/dpt_scsi.c: a sleep-under-mutex bug in dpt_init
Product: Base System Reporter: Jia-Ju Bai <baijiaju1990>
Component: kernAssignee: freebsd-bugs (Nobody) <bugs>
Status: Closed Not A Bug    
Severity: Affects Only Me CC: hardware, scsi
Priority: ---    
Version: 11.0-RELEASE   
Hardware: Any   
OS: Any   

Description Jia-Ju Bai 2017-06-18 03:31:31 UTC
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.

Jia-Ju Bai
Comment 1 Jia-Ju Bai 2017-06-18 11:53:19 UTC
I have read the manual page of bus_dmamap_load.
This call will always return immediately and will not block for any reason.
Sorry for my wrong report, please ignore it.