cvs commit: src/sys/i386/bios apm.c
kris at FreeBSD.org
Thu Nov 15 14:47:32 PST 2007
John Baldwin wrote:
> On Wednesday 14 November 2007 05:01:32 am Kris Kennaway wrote:
>> Julian Elischer wrote:
>>> julian 2007-11-14 05:43:55 UTC
>>> FreeBSD src repository
>>> Modified files:
>>> sys/i386/bios apm.c
>>> Apply the same sort of locking done in
>>> sys/dev/acpica/acpi.c rev 1.196 a while ago:
>>> Grab Giant around calls to DEVICE_SUSPEND/RESUME in
>>> If we are resuming non-MPSAFE drivers, they need Giant held for them.
>>> This may fix some obscure suspend/resume problems. It has fixed keyrate
>>> setting problems that were triggered by cardbus (MPSAFE) changing the
>>> ordering for syscons resume (non-MPSAFE). Also, add some asserts that
>>> Giant is held in our suspend/resume and shutdown methods.
>>> Submitted by: Marko Zec
>>> Revision Changes Path
>>> 1.149 +10 -0 src/sys/i386/bios/apm.c
>> Why are we adding new unconditional giant acquisitions to the tree?
>> Devices indicate whether or not they are mpsafe, why can't this be made
> Actually, we have no way in new-bus to mark new-bus operations like bus
> enumeration, etc. MPSAFE, and much of it is not (e.g.
> attach/detach/suspend/resume, etc. functions). Additionally, making this
> conditional would require a scheme where you acquire Giant when you walk down
> the tree into a non-MPSAFE driver which would add complication to many (if
> not all) bus drivers. Considering the rarity of suspend/resume (not a
> critical-path) the overhead of adding all that may not be worth it. At some
> point when we do have locking for all device driver operations this can be
> removed, but it won't really hurt anything to leave it as it is for now.
OK thanks for the explanation.
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