May 2012 - kernelnewbies@kernelnewbies.org - Kernelnewbies Mailing Lists

Dropping one packet in a coalesced skb
by Vimal May 2, 2012

May 2, 2012

Hi, I have LSO enabled on my machine, and hence a single skb can (possibly) be multiple packets on the wire. I am writing a kernel module that tries dropping packets. Is there a way to drop just one 1500B sized TCP packet inside an skb that can be a 64KB TCP segment? This segment has about 40 packets due to LSO, and I don't want to drop all of them; just a few (2--3) packets. Can the effect be achieved if I modify skb_shinfo(skb)->gso_segs, or nr_frags? Thanks, -- Vimal

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immutable wiki?
by Bill Traynor May 2, 2012

May 2, 2012

I have an Editor account for the kernelnewbies.org wiki, but all pages are currently immutable. Was the wiki made read-only at some point? Thanks Bill

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please report distros with CONFIG_DYNAMIC_DEBUG, using ddebug_query= boot param
by Jim Cromie May 1, 2012

May 1, 2012

hi all, Ive been asked whether ddebug_query= boot param is used in any distros, I think the question seeks to determine a good deprecation schedule for it (its been obsoleted by dyndbg= in driver-core-next) Would you all be so kind as to check your favorite distros, and report the ones that have one or both ? Ubuntu 12.04 LTS lacks it: jimc@chumly:~/projects/lx/linux-2.6$ grep DYNAMIC_DEBUG /boot/config* /boot/config-3.0.0-17-generic:# CONFIG_DYNAMIC_DEBUG is not set /boot/config-3.2.0-24-generic:# CONFIG_DYNAMIC_DEBUG is not set Voyage linux also lacks it, (also debian based) Fedora-16 has config option: $ uname -a Linux groucho.jimc.earth 3.3.2-6.fc16.x86_64 #1 SMP Sat Apr 21 12:43:20 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux $ grep DYNAMIC_DEBUG /boot/config-3.3.* /boot/config-3.3.1-5.fc16.x86_64:CONFIG_DYNAMIC_DEBUG=y /boot/config-3.3.2-1.fc16.x86_64:CONFIG_DYNAMIC_DEBUG=y /boot/config-3.3.2-6.fc16.x86_64:CONFIG_DYNAMIC_DEBUG=y but its not used by default. I have modified my grub defaults: $ grep ddebug_query /etc/default/grub GRUB_CMDLINE_LINUX='quiet rhgb loglevel=8 ddebug_query="module params +p" dynamic_debug.verbose=1 nouveau.dyndbg nouveau.force_post=1 it87.dyndbg=+p nouveau.perflvl_wr=7777' FYI, the above usage will eventually be unsupported, it can be replaced in driver-core-next by either of: dyndbg="module params +p" params.dyndbg=+p params.dyndbg # defaults to +p the 2nd, 3rd forms also work for loadable modules (though params isnt one of them) thanks in advance Jim

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