From nobody Fri Nov 19 08:01:37 2021 X-Original-To: dev-commits-src-main@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 14337188BE1E; Fri, 19 Nov 2021 08:01:38 +0000 (UTC) (envelope-from git@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 "R3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4HwTdY6qWFz4fdW; Fri, 19 Nov 2021 08:01:37 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from gitrepo.freebsd.org (gitrepo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:5]) (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 did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id C9F9324D2E; Fri, 19 Nov 2021 08:01:37 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from gitrepo.freebsd.org ([127.0.1.44]) by gitrepo.freebsd.org (8.16.1/8.16.1) with ESMTP id 1AJ81buh014982; Fri, 19 Nov 2021 08:01:37 GMT (envelope-from git@gitrepo.freebsd.org) Received: (from git@localhost) by gitrepo.freebsd.org (8.16.1/8.16.1/Submit) id 1AJ81bFj014981; Fri, 19 Nov 2021 08:01:37 GMT (envelope-from git) Date: Fri, 19 Nov 2021 08:01:37 GMT Message-Id: <202111190801.1AJ81bFj014981@gitrepo.freebsd.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org From: Andriy Gapon Subject: git: 1bfdb812c786 - main - iflib_stop: drain rx tasks to prevent any data races List-Id: Commit messages for the main branch of the src repository List-Archive: https://lists.freebsd.org/archives/dev-commits-src-main List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-dev-commits-src-main@freebsd.org X-BeenThere: dev-commits-src-main@freebsd.org MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Git-Committer: avg X-Git-Repository: src X-Git-Refname: refs/heads/main X-Git-Reftype: branch X-Git-Commit: 1bfdb812c786ac2607a82633f9c84a5d16f54079 Auto-Submitted: auto-generated X-ThisMailContainsUnwantedMimeParts: N The branch main has been updated by avg: URL: https://cgit.FreeBSD.org/src/commit/?id=1bfdb812c786ac2607a82633f9c84a5d16f54079 commit 1bfdb812c786ac2607a82633f9c84a5d16f54079 Author: Andriy Gapon AuthorDate: 2021-11-19 07:56:30 +0000 Commit: Andriy Gapon CommitDate: 2021-11-19 08:00:38 +0000 iflib_stop: drain rx tasks to prevent any data races iflib_stop modifies iflib data structures that are used by _task_fn_rx, most prominently the free lists. So, iflib_stop has to ensure that the rx task threads are not active. This should help to fix a crash seen when iflib_if_ioctl (e.g., SIOCSIFCAP) is called while there is already traffic flowing. The crash has been seen on VMWare guests with vmxnet3 driver. My guess is that on physical hardware the couple of 1ms delays that iflib_stop has after disabling interrupts are enough for the queued work to be completed before any iflib state is touched. But on busy hypervisors the guests might not get enough CPU time to complete the work, thus there can be a race between the taskqueue threads and the work done to handle an ioctl, specifically in iflib_stop and iflib_init_locked. PR: 259458 Reviewed by: markj MFC after: 3 weeks Differential Revision: https://reviews.freebsd.org/D32926 --- sys/net/iflib.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/sys/net/iflib.c b/sys/net/iflib.c index 8c8cc6936f7e..1fdda2ef8462 100644 --- a/sys/net/iflib.c +++ b/sys/net/iflib.c @@ -2634,7 +2634,8 @@ iflib_stop(if_ctx_t ctx) bzero((void *)di->idi_vaddr, di->idi_size); } for (i = 0; i < scctx->isc_nrxqsets; i++, rxq++) { - /* make sure all transmitters have completed before proceeding XXX */ + gtaskqueue_drain(rxq->ifr_task.gt_taskqueue, + &rxq->ifr_task.gt_task); rxq->ifr_cq_cidx = 0; for (j = 0, di = rxq->ifr_ifdi; j < sctx->isc_nrxqs; j++, di++)