Date: Fri, 17 Feb 2023 09:49:00 -0800 From: John Baldwin <jhb@FreeBSD.org> To: Alan Somers <asomers@freebsd.org> Cc: src-committers@freebsd.org, dev-commits-src-all@freebsd.org, dev-commits-src-main@freebsd.org Subject: Re: git: 98844e99d40a - main - aio: Fix more synchronization issues in aio_biowakeup. Message-ID: <2fb2622d-8aae-af37-2e52-df7f20e27646@FreeBSD.org> In-Reply-To: <CAOtMX2iEMKpXm5bayGGpSTkLVNF4==6d3_aEQKuE0jpiwQxb4g@mail.gmail.com> References: <202302152133.31FLXEep021521@gitrepo.freebsd.org> <CAOtMX2iEMKpXm5bayGGpSTkLVNF4==6d3_aEQKuE0jpiwQxb4g@mail.gmail.com>
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On 2/15/23 2:05 PM, Alan Somers wrote: > On Wed, Feb 15, 2023 at 2:33 PM John Baldwin <jhb@freebsd.org> wrote: >> >> The branch main has been updated by jhb: >> >> URL: https://cgit.FreeBSD.org/src/commit/?id=98844e99d40a90ae89d84762e07150af3a8f89bd >> >> commit 98844e99d40a90ae89d84762e07150af3a8f89bd >> Author: John Baldwin <jhb@FreeBSD.org> >> AuthorDate: 2023-02-15 21:32:52 +0000 >> Commit: John Baldwin <jhb@FreeBSD.org> >> CommitDate: 2023-02-15 21:32:52 +0000 >> >> aio: Fix more synchronization issues in aio_biowakeup. >> >> - Use atomic_store to set job->error. atomic_set does an or >> operation, not assignment. >> >> - Use refcount_* to manage job->nbio. >> >> This ensures proper memory barriers are present so that the last bio >> won't see a possibly stale value of job->error. >> >> - Don't re-read job->error after reading it via atomic_load. >> >> Reported by: markj (1) >> Reviewed by: mjg, markj >> Differential Revision: https://reviews.freebsd.org/D38611 > > Thanks for fixing these subtle problems in aio_(read|write)v. Will you MFC too? Yes. I only noticed these while reviewing the original fix from the folks at TidalScale FWIW. -- John Baldwin
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