From owner-svn-src-head@freebsd.org Fri Aug 7 19:36:09 2020 Return-Path: Delivered-To: svn-src-head@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 1EFB7372F38; Fri, 7 Aug 2020 19:36:09 +0000 (UTC) (envelope-from mjg@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4BNbFN73NCz3bNL; Fri, 7 Aug 2020 19:36:08 +0000 (UTC) (envelope-from mjg@FreeBSD.org) Received: from repo.freebsd.org (repo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id D576F1CE80; Fri, 7 Aug 2020 19:36:08 +0000 (UTC) (envelope-from mjg@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id 077Ja8T3056735; Fri, 7 Aug 2020 19:36:08 GMT (envelope-from mjg@FreeBSD.org) Received: (from mjg@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id 077Ja831056734; Fri, 7 Aug 2020 19:36:08 GMT (envelope-from mjg@FreeBSD.org) Message-Id: <202008071936.077Ja831056734@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: mjg set sender to mjg@FreeBSD.org using -f From: Mateusz Guzik Date: Fri, 7 Aug 2020 19:36:08 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r364042 - head/sys/kern X-SVN-Group: head X-SVN-Commit-Author: mjg X-SVN-Commit-Paths: head/sys/kern X-SVN-Commit-Revision: 364042 X-SVN-Commit-Repository: base MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.33 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 07 Aug 2020 19:36:09 -0000 Author: mjg Date: Fri Aug 7 19:36:08 2020 New Revision: 364042 URL: https://svnweb.freebsd.org/changeset/base/364042 Log: vfs: release the interlock after failing to set VHOLD_NO_SMR While here add more comments. Diagnosed by: markj Reported by: pho Fixes: r362827 ("vfs: protect vnodes with smr") Modified: head/sys/kern/vfs_subr.c Modified: head/sys/kern/vfs_subr.c ============================================================================== --- head/sys/kern/vfs_subr.c Fri Aug 7 19:33:54 2020 (r364041) +++ head/sys/kern/vfs_subr.c Fri Aug 7 19:36:08 2020 (r364042) @@ -3683,19 +3683,24 @@ vdropl(struct vnode *vp) } if (!VN_IS_DOOMED(vp)) { vdrop_deactivate(vp); + /* + * Also unlocks the interlock. We can't assert on it as we + * released our hold and by now the vnode might have been + * freed. + */ return; } /* - * We may be racing against vhold_smr. + * Set the VHOLD_NO_SMR flag. * - * If they win we can just pretend we never got this far, they will - * vdrop later. + * We may be racing against vhold_smr. If they win we can just pretend + * we never got this far, they will vdrop later. */ if (!atomic_cmpset_int(&vp->v_holdcnt, 0, VHOLD_NO_SMR)) { + VI_UNLOCK(vp); /* - * We lost the aforementioned race. Note that any subsequent - * access is invalid as they might have managed to vdropl on - * their own. + * We lost the aforementioned race. Any subsequent access is + * invalid as they might have managed to vdropl on their own. */ return; }