Date: Mon, 10 Apr 2023 07:58:11 +0300 From: Konstantin Belousov <kostikbel@gmail.com> To: "Jason A. Harmening" <jah@freebsd.org> Cc: src-committers@freebsd.org, dev-commits-src-all@freebsd.org, dev-commits-src-main@freebsd.org Subject: Re: git: 7b6fe2428a97 - main - DEBUG_VFS_LOCKS: use witness if available Message-ID: <ZDOXYzk0hWzlnBVz@kib.kiev.ua> In-Reply-To: <ZDNU6whgpWktdeiw@corona> References: <202304092134.339LYYY5081080@gitrepo.freebsd.org> <ZDNU6whgpWktdeiw@corona>
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On Sun, Apr 09, 2023 at 07:14:35PM -0500, Jason A. Harmening wrote: > On Sun, Apr 09, 2023 at 09:34:34PM +0000, Konstantin Belousov wrote: > > The branch main has been updated by kib: > > > > URL: https://cgit.FreeBSD.org/src/commit/?id=7b6fe2428a97921e8df882d0a24b87094c37b468 > > > > commit 7b6fe2428a97921e8df882d0a24b87094c37b468 > > Author: Konstantin Belousov <kib@FreeBSD.org> > > AuthorDate: 2023-04-08 06:15:00 +0000 > > Commit: Konstantin Belousov <kib@FreeBSD.org> > > CommitDate: 2023-04-09 21:34:12 +0000 > > > > DEBUG_VFS_LOCKS: use witness if available > > > > The assert_vop_locked messages are ignored, and file/line information > > is not too useful. Fixing this without changing both witness and VFS > > asserts KPIs is not possible. > > What was the motivation for this change? I thought it was obvious, please look at the old assertion conditions, now in the #else blocks. They are completely unable to handle shared locks. In other words, if the current thread owns the lock shared, or does not, ASSERT_VOP_UNLOCKED/ASSERT_VOP_LOCKED silently do nothing. > At first glance it seems regressive. I've at least found the assert > messages, as well as the vnode state dumping done by vfs_badlock(), > to be really useful for quick debugging of locking issues. This is > especially true when optimization makes the backtrace and frame info > less than useful; see commit 5a4a83fd0e67a0d7787d2f3e09ef0e5552a1ffb6 > for a recent example. This is fair, and I noted it in the commit message. But better working asserts are IMO worth it. Eventually it might be fixed.
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