From owner-freebsd-net@freebsd.org Wed Apr 19 03:37:17 2017 Return-Path: Delivered-To: freebsd-net@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 73549D443D9 for ; Wed, 19 Apr 2017 03:37:17 +0000 (UTC) (envelope-from sepherosa@gmail.com) Received: from mail-ua0-x234.google.com (mail-ua0-x234.google.com [IPv6:2607:f8b0:400c:c08::234]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 2AFF81FC2 for ; Wed, 19 Apr 2017 03:37:17 +0000 (UTC) (envelope-from sepherosa@gmail.com) Received: by mail-ua0-x234.google.com with SMTP id q26so6990833uaa.0 for ; Tue, 18 Apr 2017 20:37:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=rwby7A0jbSNQgdEl8Yf/e8lMsFZoqe+S+jm60ElhII8=; b=HZ5iyqgxrfLJ4BpD8ZVBTkcNwadgRvf9QVdMw/l+qN9HneeY/FiLGRgzIoYhaxxb/F XHAfRC5rEuT4A957dGF2NHd/T+RnxT/usKOYN6WuG94yLGSzkyMaroXxNueaSIcukqZI 4Qh1jqYvQjgs9h2NHO0zgLrTlRYjnMoL1qLAvsYSYTB+wr6QzattbPrWbYZcQ2fmn9o+ iBV2btEkqrVAfkyQdms1JdWvmtOCjJBWTmhjSaNDGyLWp2iM5aTB2HaLtaePC4dEA/S+ tYLxnVrcOnLfxCz6y8OJB2aYDRRh9Q4dGKzqY7OXnMpgfbV3NmoBHlmi1Ldt5lk1S+Lh FsKQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=rwby7A0jbSNQgdEl8Yf/e8lMsFZoqe+S+jm60ElhII8=; b=X1Tb/fpM/vGQDf0Fa6FYVsUEF60hfCY+4Rs7ZlVzHcrFPaATuyFBxyoj63/Qv3ZhKb M5KT7I4Kd8kMJxn3PabLDw7S+ZGWgJQNKJ3ip5MZUZpguKkzjBBN968yHWgXy7Y2Ztq5 cwdLeTqhHlsjk0Hn5fA6Y2QeXFht88+SlXZbdGsKjf85Gm3MFSVWvtbFRNDWAhZ0LPIi 2PH7Qt911WR8w18m6srq6Isg4Xoww/rZiUE5A1ArXIP5ZjIb9JKfgkRXAEAFkHIocxeB f5M0SjkjvUgv/mUxiZMO7z3vDd+rZlcYOz6vEg/msKlDoi3F6fYtLbOpCh+6e3dehmqY YNAQ== X-Gm-Message-State: AN3rC/7JSoFFPwnUt7NAJg4IgfPPBnkGLCENZqtpPb+pbIwG2Y8Q/Gni ph/b2RsE/ZhZ11TG6tAFNuAeEhxYuQ== X-Received: by 10.176.5.194 with SMTP id e60mr317569uae.71.1492573036287; Tue, 18 Apr 2017 20:37:16 -0700 (PDT) MIME-Version: 1.0 Received: by 10.176.80.97 with HTTP; Tue, 18 Apr 2017 20:37:15 -0700 (PDT) In-Reply-To: References: From: Sepherosa Ziehau Date: Wed, 19 Apr 2017 11:37:15 +0800 Message-ID: Subject: Re: Question on taskqueue_drain To: "Somayajulu, David" Cc: "freebsd-net@freebsd.org" Content-Type: text/plain; charset=UTF-8 X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 19 Apr 2017 03:37:17 -0000 On Wed, Apr 19, 2017 at 10:39 AM, Somayajulu, David wrote: > Sorry what I meant to ask was, whether it is O.K to call taskqueue_drain(), when an MTX_DEF lock is grabbed prior to calling taskqueue_drain(). > You will hit WITNESS, if the drain needs to wait; that's probably the best case. If the lock will be acquired in the task being drained, this leads to deadlock. Thanks, sephe -- Tomorrow Will Never Die