From owner-freebsd-net@freebsd.org Tue Dec 20 20:45:16 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 45450C89A94 for ; Tue, 20 Dec 2016 20:45:16 +0000 (UTC) (envelope-from adrian.chadd@gmail.com) Received: from mail-wj0-x233.google.com (mail-wj0-x233.google.com [IPv6:2a00:1450:400c:c01::233]) (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 CF18C16DB; Tue, 20 Dec 2016 20:45:15 +0000 (UTC) (envelope-from adrian.chadd@gmail.com) Received: by mail-wj0-x233.google.com with SMTP id xy5so185826115wjc.0; Tue, 20 Dec 2016 12:45:15 -0800 (PST) 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=E0exgaAZkvJ/zIaJs6K7e+sZ6ZjgZ0bymYyxRbdzwWI=; b=iFkQS/CUt6LQnF/roQJOmwtg36u1g2lm8sIrK4DoQEo7raOLUvILVhPxxsB2dBhfpV w1YghGWvL2DHwQ+P//aWv/Epvdlm8ZLORa0xH8EUxmLwrlg/lXiFtC0W6VopEV3XfCyN 2jzOtADW3R49lJmgkZ6yTeM+PQVv6cw3Nfmp9vtGbm9aN4X5QwVj/iQAUyQ5g3H1dbFW HSd2S4OxeQNhDQBPWCmTi71A4lRKhZ51QXjQ96WpU0UlJwNZ5vPIKLGWrTfATLZ11McT xuTKWLy2/q5MhlsLEhkfWUkOj4/XQQYtscEh8kAnoCxISLOy/5KD5ZLUNHp5UEqqSw4O xevQ== 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=E0exgaAZkvJ/zIaJs6K7e+sZ6ZjgZ0bymYyxRbdzwWI=; b=MzDz2hMowVEHjDtycYof8wRJORHe/7TqpRo3x8tu3HEJV6AUpTBfhVJ4uD3DUzSu5r qlTig9rYwIjrIDNt2FX94gEHhfkYSQ/nfMfKiPcRgoTtMGXERdWEQNdsnzxcPdcjoaYj l568nnCcgDbhnoP+C/+NdOg+1EYPK8jFhcpXcYS+hl2WIDeYybR0GgmSdXOLhlFOFxYi 4rYyVIHJWorWB06XWyKEoxl2SuS7bd48/vraZSP/gG2xlhE8OTNYcZzHYTDMngPSDVXZ JfRvXpMrtKTCJi/yXE8AziBA0WA5NtK5yxXHffO578lyc1kokQBIeDCpkMV45lTeCvE5 7wIQ== X-Gm-Message-State: AIkVDXLnaks+uORbUik4B7dXGlpOpgtJs7J1S0ivBKQVaxyzo9SVbkNDcpHrCjfDOZDkumk3gJkiNUvy/fZ+RA== X-Received: by 10.194.67.67 with SMTP id l3mr521656wjt.151.1482266714116; Tue, 20 Dec 2016 12:45:14 -0800 (PST) MIME-Version: 1.0 Received: by 10.194.44.1 with HTTP; Tue, 20 Dec 2016 12:45:13 -0800 (PST) In-Reply-To: References: <20161217222812.GA4979@ox> From: Adrian Chadd Date: Tue, 20 Dec 2016 12:45:13 -0800 Message-ID: Subject: Re: cxgbe's native netmap support broken since r307394 To: Vincenzo Maffione Cc: Navdeep Parhar , "freebsd-net@freebsd.org" , Luigi Rizzo , 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: Tue, 20 Dec 2016 20:45:16 -0000 hi, What's the commit? We should get it into -HEAD asap. -adrian On 20 December 2016 at 01:25, Vincenzo Maffione wrote: > Ok, applied to the netmap github repo. > This fix will be published when Luigi does the next commit on FreeBSD. > > Cheers, > Vincenzo > > 2016-12-19 20:05 GMT+01:00 Navdeep Parhar : >> 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" > > > > -- > 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"