LOR: acpi_dock vs sysctl

[Ulrich Spörlein]

Hi, just turned on WITNESS as my laptop freezes from time to time and
among the many LORs, here's a new one:

lock order reversal:
 1st 0xc09f3484 sysctl lock (sysctl lock) @ /usr/src/sys/kern/kern_sysctl.c:1521
 2nd 0xc0eed504 ACPI Docking Station (ACPI Docking Station) @ /usr/src/sys/modules/acpi/acpi_dock/../../../dev/acpica/acpi_dock.c:423
KDB: stack backtrace:
db_trace_self_wrapper(c09394fe,fb807aac,c062e515,c061e8ab,c093c4d8,...) at db_trace_self_wrapper+0x26
kdb_backtrace(c061e8ab,c093c4d8,c4188da8,c418ae28,fb807b08,...) at kdb_backtrace+0x29
_witness_debugger(c093c4d8,c0eed504,c0eec1cb,c418ae28,c0eec15e,...) at _witness_debugger+0x25
witness_checkorder(c0eed504,9,c0eec15e,1a7,0,...) at witness_checkorder+0x839
_sx_xlock(c0eed504,0,c0eec15e,1a7,0,...) at _sx_xlock+0x85
acpi_dock_status_sysctl(c44c20c0,c42d0e80,0,fb807ba4,fb807ba4,...) at acpi_dock_status_sysctl+0x49
sysctl_root(fb807ba4,0,c0936c1e,5f1,c47bb000,...) at sysctl_root+0x187
userland_sysctl(c47bb000,fb807c10,4,0,bfbfdc40,...) at userland_sysctl+0x17c
__sysctl(c47bb000,fb807cf8,c0972725,c093d30d,c47ead48,...) at __sysctl+0x94
syscall(fb807d38) at syscall+0x220
Xint0x80_syscall() at Xint0x80_syscall+0x20
--- syscall (202, FreeBSD ELF32, __sysctl), eip = 0x2818cc1b, esp = 0xbfbfdb4c, ebp = 0xbfbfdb78 ---


btw, my laptop freezes sometimes when docking/undocking, not sure if
this is related then.