From owner-freebsd-drivers@freebsd.org Sun Jun 18 07:47:54 2017 Return-Path: Delivered-To: freebsd-drivers@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 CBF0CD8B633; Sun, 18 Jun 2017 07:47:54 +0000 (UTC) (envelope-from baijiaju1990@163.com) Received: from m12-18.163.com (m12-18.163.com [220.181.12.18]) by mx1.freebsd.org (Postfix) with ESMTP id 22DAB34FD; Sun, 18 Jun 2017 07:47:53 +0000 (UTC) (envelope-from baijiaju1990@163.com) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=Subject:From:Message-ID:Date:MIME-Version; bh=Y9Xmg Sn220IM0qmoKQUrY5F8HBdtOf/WBvRB5w/ae2Y=; b=IJQKAyCwqIurQPoavP1k2 ymbikfZtJdm3Xexz5sMH20962+eM2MLPzeNxbN7dMSgDdI9PW6hPPZeZ6so3iKYE trJ76rZYb9Lka8SRqxo1K/1HgjnVRTbwH+OMWFAC2krJ6EmpT9XhFRxo4S15W6oS biuJsmcyU7FvX5XZWjNQlY= Received: from [166.111.70.13] (unknown [166.111.70.13]) by smtp14 (Coremail) with SMTP id EsCowAA3S7wiMEZZkndnNQ--.42905S2; Sun, 18 Jun 2017 15:47:46 +0800 (CST) Subject: Re: [Bug 220032] [if_alc] sys/dev/alc/if_alc.c: sleep-under-mutex bugs To: Kevin Oberman Cc: freebsd-drivers@freebsd.org, "freebsd-net@freebsd.org" References: <7cc5abf5-f90c-c554-e54e-6f9534ef22ef@163.com> From: Jia-Ju Bai Message-ID: Date: Sun, 18 Jun 2017 15:47:46 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.2.0 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US X-CM-TRANSID: EsCowAA3S7wiMEZZkndnNQ--.42905S2 X-Coremail-Antispam: 1Uf129KBjvJXoW7WrWxKw47uw1DZF47Wr4DJwb_yoW8ur4rp3 yagas0yryDCrWfA3s7Ar1xAFyfX395GrZ8WF45WrZFqwn8Wry2gr1SgFWUZFyrur9xCFWI yrWUX395Zan0yaDanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x07ja4E_UUUUU= X-Originating-IP: [166.111.70.13] X-CM-SenderInfo: xedlyx5dmximizq6il2tof0z/1tbiGAL6elXlaIY1DQAAs8 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-Content-Filtered-By: Mailman/MimeDel 2.1.23 X-BeenThere: freebsd-drivers@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Writing device drivers for FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 18 Jun 2017 07:47:54 -0000 Thanks a lot, your advice is very helpful :) I will submit a patch according to your advice, and update my bug report. By the way, I have found many similar possible bugs in network drivers in FreeBSD. And they are all caused by "BUS_DMA_WAITOK" in bus_dmamap_load and other dmamap-load related functions. If my reported bugs can be quickly confirmed, I will write and submit patches for them as soon as possible. I am looking forward to helpful comments and advice :) Thanks, Jia-Ju Bai On 2017/6/18 13:31, Kevin Oberman wrote: > On Fri, Jun 16, 2017 at 2:03 AM, Jia-Ju Bai > wrote: > > The alc driver may sleep under a mutex, and the function call > paths in file > "sys/dev/alc/if_alc.c" in FreeBSD 11.0 is: > alc_resume [line 2648: acquire the mutex] > alc_init_locked [line 2664] > alc_init_rx_ring [line 3911] > alc_newbuf [line 4469] > bus_dmamap_load_mbuf_sg(BUS_DMA_WAITOK) [line 3472] --> > may sleep > > alc_int_task [line 3330: acquire the mutex] > alc_start_locked [line 3372] > alc_encap [line 2942] > bus_dmamap_load_mbuf_sg(BUS_DMA_WAITOK) [line 2780] --> may > sleep > > The possible fix of these bugs is to set the last parameter in > bus_dmamap_load_mbuf_sg to "BUS_DMA_NOWAIT". > > This bug is found by a static analysis tool written by myself, and > it is > checked by my review of the FreeBSD code. > > By the way, I am a freshman in developing FreeBSD drivers, and I > am willing to > submit a patch. But I do not know how to write and submit a patch, > and where to > submit, so I am looking forward to useful advice :) > > Jia-Ju Bai > > > To submit a patch, use svn to download the source from a repository. > Be sure the file in your source directory is the current, unmodified file. > Edit the file or files as needed to correct the bug > Generate the diff with the command "svn diff > path-to-directory-containing-file(s) > diff-file.diff" > Update the bug report attaching the patch (with a brief description) > -- > Kevin Oberman, Part time kid herder and retired Network Engineer > E-mail: rkoberman@gmail.com > PGP Fingerprint: D03FB98AFA78E3B78C1694B318AB39EF1B055683