[Bug 220096] [acpi] sys/dev/acpica/acpi_thermal.c: a sleep-under-mutex bug in acpi_tz_thread

[Jia-Ju Bai]

The driver may sleep under a mutex, and the code path in file 
"sys/dev/acpica/acpi_thermal.c" in FreeBSD 11.0 release is:
acpi_tz_thread [line 992: acquire the mutex]
acpi_tz_thread [line 993]
acpi_tz_thread [line 1003]
acpi_tz_thread [line 1004] (msleep is excuted)
acpi_tz_thread [line 1008]
acpi_tz_thread [line 970]
acpi_tz_thread [line 971]
acpi_tz_thread [line 975]
   malloc(M_WAITOK) [line 976]

The possible fix of this bug is to replace "M_WAITOK" in malloc with 
"M_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