Date: Wed, 18 Aug 2021 12:54:49 -0500
From: Kyle Evans <kevans@freebsd.org>
Cc: src-committers <src-committers@freebsd.org>, "<dev-commits-src-all@freebsd.org>" <dev-commits-src-all@freebsd.org>, dev-commits-src-main@freebsd.org
Subject: Re: git: d7e1bdfebacc - main - uipc: avoid circular pr_{slow, fast}timos
Message-ID: <CACNAnaHmR=xfDvyv471N%2B_aE61K85MvM0d4RQ0JqwtxWKhO83w@mail.gmail.com>
In-Reply-To: <202108181754.17IHs1Ub030989@gitrepo.freebsd.org>
References: <202108181754.17IHs1Ub030989@gitrepo.freebsd.org>
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On Wed, Aug 18, 2021 at 12:54 PM Kyle Evans <kevans@freebsd.org> wrote: > > The branch main has been updated by kevans: > > URL: https://cgit.FreeBSD.org/src/commit/?id=d7e1bdfebacc4de25dc51e14a91d66bb429677c9 > > commit d7e1bdfebacc4de25dc51e14a91d66bb429677c9 > Author: Kyle Evans <kevans@FreeBSD.org> > AuthorDate: 2021-08-18 17:31:45 +0000 > Commit: Kyle Evans <kevans@FreeBSD.org> > CommitDate: 2021-08-18 17:46:54 +0000 > > uipc: avoid circular pr_{slow,fast}timos > This should read "avoid circular pf{fast,slow}_list", sorry. > domain_init() gets reinvoked for each vnet on a system, so we must not > alter global state. Practically speaking, we were creating circular > lists and tying up a softclock thread into an infinite loop. > > The breakage here was most easily observed by simply creating a jail > in a new vnet and watching the system suddenly become erratic. > > Reported by: markj > Fixes: e0a17c3f063f ("uipc: create dedicated lists for fast ...") > Pointy hat: kevans > --- > sys/kern/uipc_domain.c | 23 +++++++++++++++++------ > 1 file changed, 17 insertions(+), 6 deletions(-) > > diff --git a/sys/kern/uipc_domain.c b/sys/kern/uipc_domain.c > index 0946a2a75326..d572e0ec19db 100644 > --- a/sys/kern/uipc_domain.c > +++ b/sys/kern/uipc_domain.c > @@ -194,12 +194,23 @@ domain_init(void *arg) > (*dp->dom_init)(); > for (pr = dp->dom_protosw; pr < dp->dom_protoswNPROTOSW; pr++) { > protosw_init(pr); > - rm_wlock(&pftimo_lock); > - if (pr->pr_fasttimo != NULL) > - LIST_INSERT_HEAD(&pffast_list, pr, pr_fasttimos); > - if (pr->pr_slowtimo != NULL) > - LIST_INSERT_HEAD(&pfslow_list, pr, pr_slowtimos); > - rm_wunlock(&pftimo_lock); > + > + /* > + * Note that with VIMAGE enabled, domain_init() will be > + * re-invoked for each new vnet that's created. The below lists > + * are intended to be system-wide, so avoid altering global > + * state for non-default vnets. > + */ > + if (IS_DEFAULT_VNET(curvnet)) { > + rm_wlock(&pftimo_lock); > + if (pr->pr_fasttimo != NULL) > + LIST_INSERT_HEAD(&pffast_list, pr, > + pr_fasttimos); > + if (pr->pr_slowtimo != NULL) > + LIST_INSERT_HEAD(&pfslow_list, pr, > + pr_slowtimos); > + rm_wunlock(&pftimo_lock); > + } > } > > /*
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