Hi. On Tuesday 31 January 2006 20:58, Rafael J. Wysocki wrote: > Hi, > > > > > > > > + if (freezer_is_on()) > > > > + return 0; > > > > + > > > > if (path[0] == '\0') > > > > return 0; > > > > > > Disabling the usermode helper while freeze_processes() is executed > > > seems to be a good idea to me, but I think it should be done with a > > > mutex or something like that. > > > > With the refrigerator code you guys are using at the moment, ouldn't that > > result in deadlocks when we later try to freeze the process in > > preparation for the atomic restore? (Or perhaps you don't freeze > > processes at that point?) > > I'm not sure what you mean. I said "mutex" because you seem to have a race > here (the freezer may be started right after the freezer_is_on() check). > IMO the freezer should disable the invocations of new usermode helpers and > wait util all of the already running helpers are finished. For this > purpose two variables would be needed and a lock. Sorry. Being a bit thick. I wasn't worried about already-running usermode helpers (or about-to-run helpers either) because the spawned processes would either complete or be caught be the usual freezing code. My concern was more that new invocations of this path don't leave us with unfrozen processes hanging around. That said, I think you have a valid point about letting existing helpers run to completion. It does make me concerned though about the possibility of a long-lived helper (not that I know that there really are such things at the moment). Do you think that needs to be taken as a genuine concern? If so, I guess we then need to make freezing a four stage process: 1. Stop new usermodehelpers from starting & let existing ones run to completion. 2. Freeze userspace. 3. Freezer bdevs. 4. Freezer kernel space. Regards, Nigel -- See our web page for Howtos, FAQs, the Wiki and mailing list info. http://www.suspend2.net IRC: #suspend2 on Freenode
Attachment:
pgp7LiF3pY8Su.pgp
Description: PGP signature
- Follow-Ups:
- Re: [ 06/23] [Suspend2] Disable usermode helper invocations when the freezer is on.
- From: "Rafael J. Wysocki" <[email protected]>
- Re: [ 06/23] [Suspend2] Disable usermode helper invocations when the freezer is on.
- References:
- [ 00/23] [Suspend2] Freezer Upgrade Patches
- From: Nigel Cunningham <[email protected]>
- Re: [ 06/23] [Suspend2] Disable usermode helper invocations when the freezer is on.
- From: Nigel Cunningham <[email protected]>
- Re: [ 06/23] [Suspend2] Disable usermode helper invocations when the freezer is on.
- From: "Rafael J. Wysocki" <[email protected]>
- [ 00/23] [Suspend2] Freezer Upgrade Patches
- Prev by Date: Re: Badness in local_bh_enable by [PATCH] fix uidhash_lock <-> RCU deadlock
- Next by Date: Re: [PATCH] timer tsc ensure we allow for initial tsc and tsc sync
- Previous by thread: Re: [ 06/23] [Suspend2] Disable usermode helper invocations when the freezer is on.
- Next by thread: Re: [ 06/23] [Suspend2] Disable usermode helper invocations when the freezer is on.
- Index(es):
 |