Date: Sun, 18 Jun 2017 19:42:39 +0800 From: Jia-Ju Bai <baijiaju1990@163.com> To: Kevin Oberman <rkoberman@gmail.com> Cc: freebsd-drivers@freebsd.org, "freebsd-net@freebsd.org" <freebsd-net@freebsd.org> Subject: Re: [Bug 220032] [if_alc] sys/dev/alc/if_alc.c: sleep-under-mutex bugs Message-ID: <00aa0c88-70b6-cb34-461e-34e25029f481@163.com> In-Reply-To: <fbc0f04f-b7cf-ee86-9681-d6dd97122038@163.com> References: <7cc5abf5-f90c-c554-e54e-6f9534ef22ef@163.com> <CAN6yY1uQxR3HTLYzy3uOwpcbLFGAKtCBxRU1HPAb8jjGVC9Hkg@mail.gmail.com> <fbc0f04f-b7cf-ee86-9681-d6dd97122038@163.com>
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Hi, I have read the manual page ofbus_dmamap_load and other dmamap-load related functions. These calls will always return immediately and will not block for any reason. Sorry for my wrong report, please ignore it. Thanks, Jia-Ju Bai On 2017/6/18 15:47, Jia-Ju Bai wrote: > 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 <baijiaju1990@163.com >> <mailto:baijiaju1990@163.com>> 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 <mailto:rkoberman@gmail.com> >> PGP Fingerprint: D03FB98AFA78E3B78C1694B318AB39EF1B055683 >
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