netdev - Re: [PATCH net 2/3] net: cdc_mbim: send ZLP after max sized NTBs

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 21 Jan 2013 18:56:10 +0200
From:	Yauheni Kaliuta <y.kaliuta@...il.com>
To:	Bjørn Mork <bjorn@...k.no>
Cc:	netdev@...r.kernel.org, linux-usb@...r.kernel.org,
	Greg Suarez <gsuarez@...thmicro.com>,
	Alexey Orishko <alexey.orishko@...ricsson.com>,
	Oliver Neukum <oneukum@...e.de>
Subject: Re: [PATCH net 2/3] net: cdc_mbim: send ZLP after max sized NTBs


Hi, Bjørn!

>>>>> "BM" == Bjørn Mork writes:

 > We normally avoid sending ZLPs by padding NTBs with a zero byte
 > if the NTB is shorter than dwNtbOutMaxSize, resulting in a short
 > USB packet instead of a ZLP.  But in the case where the NTB length
 > is exactly dwNtbOutMaxSize and this is an exact multiplum of
 > wMaxPacketSize, then we must send a ZLP.

The idea of NCM was to avoid extra ZLPs. If your transfer is exactly
dwNtbOutMaxSize, it's known, you can submit such request on the receiver
side and you do not need any EOT indicatation, so the frametime can be
used for useful data.

I didn't check MBIM specs, but I guess, it wasn't changed. But better get
Alexey's answer for sure.

 > This fixes an issue seen on a Sierra Wireless MC7710 device
 > where the transmission would fail whenever we ended up padding
 > the NTBs to max size.

Is it buggy?

 > Signed-off-by: Bjørn Mork <bjorn@...k.no>
 > ---
 >  drivers/net/usb/cdc_mbim.c |    2 +-
 >  1 file changed, 1 insertion(+), 1 deletion(-)

 > diff --git a/drivers/net/usb/cdc_mbim.c b/drivers/net/usb/cdc_mbim.c
 > index 42f51c7..3a5673a 100644
 > --- a/drivers/net/usb/cdc_mbim.c
 > +++ b/drivers/net/usb/cdc_mbim.c
 > @@ -366,7 +366,7 @@ err:
 >  
 >  static const struct driver_info cdc_mbim_info = {
 >          .description = "CDC MBIM",
 > -        .flags = FLAG_NO_SETINT | FLAG_MULTI_PACKET | FLAG_WWAN,
 > +        .flags = FLAG_NO_SETINT | FLAG_MULTI_PACKET | FLAG_WWAN | FLAG_SEND_ZLP,
 >          .bind = cdc_mbim_bind,
 >          .unbind = cdc_mbim_unbind,
 >          .manage_power = cdc_mbim_manage_power,
 > -- 
 > 1.7.10.4



-- 
WBR, Yauheni Kaliuta
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html