From owner-freebsd-net@freebsd.org Mon Dec 19 19:05:43 2016 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 D46ACC88EC3 for ; Mon, 19 Dec 2016 19:05:43 +0000 (UTC) (envelope-from nparhar@gmail.com) Received: from mail-lf0-x243.google.com (mail-lf0-x243.google.com [IPv6:2a00:1450:4010:c07::243]) (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 5B2591829; Mon, 19 Dec 2016 19:05:43 +0000 (UTC) (envelope-from nparhar@gmail.com) Received: by mail-lf0-x243.google.com with SMTP id p100so8346061lfg.2; Mon, 19 Dec 2016 11:05:43 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:sender:in-reply-to:references:from:date:message-id :subject:to:cc; bh=No+x5JGeHdmBNBPUfUs1eUNvHuVKX3ElsxN7O8jnl7c=; b=i6A45Url5abT/g+l0pzmMjrVCLS/XDiLBU5zKIunF60uNSZgX45B0aaxe7nTTGYsMz zwR5SM75Bl+dyhsfXcIrFCcRqOuVKOE1YcH4brk54TpPSjNdMUIbGseh2j9SRy3fYO15 rPfsU/uqsBxbQRF9597KRaxWXDAVKOMtSPEdrbwZjoEe84qHiGVlOIvOUAqu+4lqx58t OBved/hO8QQoeQzdAXRQETAyP7/Jg5sItgIx3ZcSiUx3PtAAckrPTdwIfHQLd58uj2x6 2C9w0E/L8NriDvqbXXVYQ97Tywo1zuV/2jyA4H/+BPfoV0H4JnDt/pt3/ZTUjLT27mT1 EeCA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:sender:in-reply-to:references:from :date:message-id:subject:to:cc; bh=No+x5JGeHdmBNBPUfUs1eUNvHuVKX3ElsxN7O8jnl7c=; b=nR5SZrMOCk/26YYlTT9uqr2vlxmui/JJDW0HFkXwlklLOpMZHlyKex5mTpvn7hQUxC qMy4yvTCtfdSLLW/1MkXaDK2YzUO7hOCCcpSw475L3DlBYybHvFSF5NAUxVCtmPOxN7x BRAGgK+3D1hximiwdkiMgNI4cCYgCVqQNQDKe4RGPv81yGEUq8fU5NTK+uE0U5yJjqiF s73lW0bMRJ/hzaNX40uR0nnb9uobzvrG3FOYxvhV/DCQOQJ4g4s0OsT3MysEU+RyGIwX GnhNEomN23GZEXokBrK+wNkY8vKMRNJjfkPmga/BSvbZDq5lsIwmN45qMHMXEP/d+Jyl 9BlA== X-Gm-Message-State: AKaTC03Qjcdd5pbLW7tdjtG5rMLP9+8eewTA9YNAl8T6Y5v0MQzXGgVNSILcugO8ogCk/eCJWZoFHpqgTCzyMw== X-Received: by 10.25.199.145 with SMTP id x139mr5070435lff.142.1482174341431; Mon, 19 Dec 2016 11:05:41 -0800 (PST) MIME-Version: 1.0 Sender: nparhar@gmail.com Received: by 10.25.208.141 with HTTP; Mon, 19 Dec 2016 11:05:40 -0800 (PST) In-Reply-To: References: <20161217222812.GA4979@ox> From: Navdeep Parhar Date: Mon, 19 Dec 2016 11:05:40 -0800 X-Google-Sender-Auth: gzp0SXbIft2ytBL5fSyudcFuBwQ Message-ID: Subject: Re: cxgbe's native netmap support broken since r307394 To: Vincenzo Maffione Cc: Luigi Rizzo , "freebsd-net@freebsd.org" , Giuseppe Lettieri 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: Mon, 19 Dec 2016 19:05:43 -0000 IFNET_RLOCK will work, thanks. Navdeep On Mon, Dec 19, 2016 at 3:21 AM, Vincenzo Maffione wrote: > Hi Navdeep, > > Indeed, we have reviewed the code, and we think it is ok to > implement nm_os_ifnet_lock() with IFNET_RLOCK(), instead of using > IFNET_WLOCK(). > Since IFNET_RLOCK() results into sx_slock(), this should fix the issue. > > On FreeBSD, this locking is needed to protect a flag read by nm_iszombie(). > However, on Linux the same lock is also needed to protect the call to > the nm_hw_register() callback, so we prefer to have an "unified" > locking scheme, i.e. always calling nm_hw_register under the lock. > > Does this make sense to you? Would it be easy for you to make a quick > test by replacing IFNET_WLOCK with IFNET_RLOCK? > > Thanks, > Vincenzo > > 2016-12-17 23:28 GMT+01:00 Navdeep Parhar : >> Luigi, Vincenzo, >> >> The last major update to netmap (r307394 and followups) broke cxgbe's >> native netmap support. The problem is that netmap_hw_reg now holds an >> rw_lock around the driver's netmap_on/off routines. It has always been >> safe for the driver to sleep during these operations but now it panics >> instead. >> >> Why is IFNET_WLOCK needed here? It seems like a regression to disallow >> sleep on the control path. >> >> Regards, >> Navdeep >> >> begin_synchronized_op with the following non-sleepable locks held: >> exclusive rw ifnet_rw (ifnet_rw) r = 0 (0xffffffff8271d680) locked @ >> /root/ws/head/sys/dev/netmap/netmap_freebsd.c:95 >> stack backtrace: >> #0 0xffffffff810837a5 at witness_debugger+0xe5 >> #1 0xffffffff81084d88 at witness_warn+0x3b8 >> #2 0xffffffff83ef2bcc at begin_synchronized_op+0x6c >> #3 0xffffffff83f14beb at cxgbe_netmap_reg+0x5b >> #4 0xffffffff809846f1 at netmap_hw_reg+0x81 >> #5 0xffffffff809806de at netmap_do_regif+0x19e >> #6 0xffffffff8098121d at netmap_ioctl+0x7ad >> #7 0xffffffff8098682f at freebsd_netmap_ioctl+0x5f > > > > -- > Vincenzo Maffione > _______________________________________________ > freebsd-net@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-net > To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org"