SMP General TODO List

This page lists some general locking/basic SMP todo items that have thus far slipped through the cracks; some are more relevant to the real world than others. For these purposes, we consider a component to be not MPSAFE if it either entirely relies on the Giant lock to operate correctly, or if its required dependencies rely on the Giant lock to operate correctly. Depending on the subsystem, the impact may be significant or limited with respect to other components simultaneously operating in the kernel. Some have owners, some don't.

Subsystem

Dependencies

Owner

Some TTY drivers override the per-TTY mutex: syscons (Giant), si (Giant), nmdm and usb_serial

ed

syscons is not MPSAFE

ed

Some CAM SCSI drivers are not mpsafe (XXX need list)

KAME IPv6 ND6 and MLD6 are not MPSAFE. More details on IPv6TODO.

Network address lists are insufficiently locked

rwatson

Many pseudo-devices are not yet marked as MPSAFE, even though many are in fact MPSAFE. (i.e. mem)

(maybe) ed

Giant is still acquired at some points in VM

swap handling, MPSAFE VFS

alc

Giant is still acquired in System V SHM

wkoszek

Some filesystems are not mpsafe. These are (that do not set MNTK_MPSAFE as mount flag): hpfs, ntfs, nwfs, smbfs, coda, portalfs.

Mounting and unmounting of filesystems acquires Giant

The non-MPSAFE timeout() API is used in the following kernel systems: acpi, scsi_low, ipfilter, advansys, amr, atkbdc, sbp, hptmv, hptrr, iir, ips, isp, mcd, mly, mn, scd, syscons, twa, sysbeep, if_slowtimo, netatalk, ng_btsocket, ng_fec, netipsec, netncp, ncr

netatalk uses the non-MPSAFE timeout() API

rwatson

The netncp and netsmb code unconditionally acquire Giant

ALTQ uses non-mpsafe callouts

The following drivers use non-mpsafe callouts: dev/mpt/mpt_raid.c dev/esp/ncr53c9x.c dev/kbdmux/kbdmux.c dev/lmc/if_lmc.c dev/rc/rc.c dev/uart/uart_kbd_sun.c

Module event handlers run under Giant

linux_getcwd_common() (should use LK_SHARED and MPSAFEVFS)

Linux compat ioctl() handlers

SVR4 compat streams

start_init()

SYSINIT() routines

ntp system calls and settime()

reboot()

Excluded from this list are a large number of post-SMPng optimization tasks relating to scheduling, locking strategy, etc, that are described elsewhere.


SMPTODO (last edited 2012-10-15 16:36:27 by RomanDivacky)