July 2014 - kernelnewbies@kernelnewbies.org - Kernelnewbies Mailing Lists

How to decode a kernel symbol
by Santhosh Kumar July 20, 2014

July 20, 2014

To debug a problem I added some debugs in the kernel code to print the address at which a lock is taken, by calling __builtin_return_address(1). How do I find the symbol (function name) corresponding to the address printed ? Apologies if this is an often repeated question here. In that case would appreciate if someone can point a link covering this.

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prashantpatil321@gmail.com has indicated you're a friend. Accept?
by prashantpatil321＠gmail.com July 19, 2014

July 19, 2014

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Re: How to automate checkpatch && get_maintainers && git send-email of commits range?
by Joe Perches July 18, 2014

July 18, 2014

On Fri, 2014-07-18 at 18:22 -0400, Theodore Ts'o wrote: > On Fri, Jul 18, 2014 at 05:38:30PM +0300, Andrey Utkin wrote: > > Is there script for automated checkpatch.pl && get_maintainers.pl && > > git send-email for range of commits? I see none. Would it be welcome > > to submit such one to kernel tree? > > Too much automation can be a really bad thing. You **really** want to > sanity check the output of checkpatch.pl True. checkpatch should not be used on existing commits. checkpatch should be used prior to committing. > and get_maintainers.pl. I think checkpatch is pretty good about cc'ing mostly the right folk by default. Where it's not adequate is when some particular bit of code was written by someone not the maintainer and that writer should also be copied on a patch. Many different command-line options exist for get_maintainer. Perhaps too many. --git-blame can be used with patches to also list the author of any modified commit. Using that option can take a fairly long while to run though. > Their output is not always correct, and some amount of human common > sense is required. True. Experience is more of a benefit than common sense here. > And then think very hard about which patches people need to see in > order to be able to evaluate a patch. For example, if you have patch > 1 out of a series which adds a new function, and then patches 2 > through 1000 modify a thousand different drivers to use that new > function, if you use an automated get_maintainers.pl script to send > each patch to just the maintainer, then the device driver maintainer > might not see patch #1 which is critical context to understanding the > patch that you want to make to his driver. And then you will have > several hundred very angry and annoyed developers wondering why you > sent them patch 345/1000, with no other context, and wondering what > the heck they are supposed to do with the email that you have just > launched into their inbox. There is no good solution to this problem. You can't cc the world on patch 1/n (vger rejects emails with too many recipients) and cc just the maintainers on x/n. One solution is to send the 0/n and 1/n patches to all the email lists that are cc'd on any single patch of large patch series. A better solution might be to send _only_ the 1/n patch to lkml and to someone like Andrew Morton with an explanation as to why it's useful, wait for it to be applied, then send the large patch series during the next release cycle. > There's a reason why many developers cordially hate these scripts; > it's too easy to misuse them, Yup, though cordial can be a misdescription for some of those developers... I hope everyone enjoys their weekends...

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Re: How to automate checkpatch && get_maintainers && git send-email of commits range?
by Andrey Utkin July 18, 2014

July 18, 2014

2014-07-18 17:46 GMT+03:00 Benoit Taine <benoit.taine(a)lip6.fr>: > On 18/07/2014 17:38, Andrey Utkin wrote: >> Is there script for automated checkpatch.pl && get_maintainers.pl && >> git send-email for range of commits? I see none. Would it be welcome >> to submit such one to kernel tree? > You can use `splitpatch` to split a patch into multiple mails with the > correct mailing list and maintainers. It generates a script to > chain-send these emails using `cocci-send-email` (a modified version of > `git-send-email`). > > Both are available in the `tools/` directory of coccinelle's > distribution <http://coccinelle.lip6.fr/>. Thank you for this info, but it doesn't match exactly what i seek for. I'd like to automate checking and sending exactly of range of git commits, or of a set of files generated by git-format-patch. I also cannot use cocci-send-email because it doesn't pick To: and Cc: lines which i inject into git-format-patch-formatted files. And i don't know tools to format the patches in "The original format used by Greg Kroah-Hartman's send_lots_of_email.pl script". My target should be to - check all patches, - find set of email addresses to Cc for each patch, - send them at once to correct sets of addresses, entering SMTP password only once if it is not stored in git-config. 2014-07-18 17:55 GMT+03:00 Alexey Dobriyan <adobriyan(a)gmail.com>: >> Is there script for automated checkpatch.pl && get_maintainers.pl && >> git send-email for range of commits? I see none. Would it be welcome >> to submit such one to kernel tree? > > Spurious checkpatch.pl changes increasing number of git-blame > "false positives" are more than enough. Alexey, sorry, I completely don't get you, could you please elaborate your reply? -- Andrey Utkin

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module_param does not work in Ubuntu 13.10 - Kernel 3.10.0-4
by dora babu July 18, 2014

July 18, 2014

Hi Kernelnewbies, Subject : module_param does not work in Ubuntu 13.10 - Kernel 3.10.0-4 For the thread in your mailing list, I would like to suggest the person who posted question that he is not able to pass the parameters to the module in their product. I would like them to check the 'insmod' binary behaviour. If they are using 'busybox'(insmod a softlink to it) for inserting the module with parameters, I would like to suggest them to try with 'insmod' generated out of its source code(compile or available over internet but not the one provided by busybox). I recently faced the same issue, and it turned out to be the issue with the busybox and worked perfectly fine with the insmod I compiled locally. -- Thanks & Regards,

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Where find Linux Kernel Development Jobs
by Lucas Tanure July 18, 2014

July 18, 2014

Hi, What are the best sites, lists, foruns to find Linux Kernel Jobs. No matter the country. Linkedin is still the best place ? Thanks -- Lucas Tanure +55 (19) 988176559

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hi , question function of net_rx(struct net_device *dev)
by lx July 18, 2014

July 18, 2014

hi : the source code of net_rx(struct net_device *dev) is: http://lxr.oss.org.cn/source/drivers/net/ethernet/cirrus/cs89x0.c#L670 I can't understand codes about malloc buffer. ########################################## 684 /* Malloc up new buffer. */ 685 skb = netdev_alloc_skb(dev, length + 2); 686 if (skb == NULL) { 687 dev->stats.rx_dropped++; 688 return; 689 } 690 skb_reserve(skb, 2); /* longword align L3 header */ ########################################## How to explain 'length + 2' in line of 685? Why add 2 ? Thank you.

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Exporting ioctls from out-of-tree module to userspace
by Daniel Hilst Selli July 17, 2014

July 17, 2014

I write an out-of-tree module and now want to export its ioctls to userspace by installing a header that my modules includes, I was looking for how to do it but can't get it.. I was trying header-y from https://www.kernel.org/doc/Documentation/kbuild/makefiles.txt but got: make[1]: *** No rule to make target 'headers_install'. Stop. Here is what I'm trying: https://gist.github.com/gkos/b0bc4e29a3147b0e6d3b I see on kernel that usually the exported headers go in include/uapi/SOMETHING and are declared on include/uapi/Kbuild.. but have no idea if this may work for out-of-tree modules, the headers_install exists on linux Makefile so the 'No rule to make target 'headers_install'' doesn't make sense to me .. I try follow headers_install target on kernel's Makefile but only got frustraded :( Any idea? ps: I compiled the module but don't loaded it, so it may have mistakes Thanks in advance! Cheers!

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downstream pci walk
by Amerei Acuna July 17, 2014

July 17, 2014

Hello I'm writing a custom PCI driver for a hobby endpoint. Due to some "special", possibly unique, circumstance, I need to determine if two devices form a pair. As I'm using a PCI switch to connect these two devices, I'm thinking on the possibility of checking if the two devices share a common pci-pci bridge (or finding the least common ancestor in a directed graph). Basically, I'm trying to implement pci/bus.c::pci_walk_bus(), only, in a downstream direction (from end point to bridge). I could use pci_bus_upstream_bridge() to do my reverse walk but I noticed it uses a semaphore pci_bus_sem that is only made available via internal "pci.h" e.g. not available to outside modules. Along with my study, I would like to ask for advice and a push in the right direction on how can I achieve a reverse PCI walk - if that is possible. Thank you in advance for your help. ~amerei

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Re: How to prevent a module from unloading when in used
by Chetan Nanda July 16, 2014

July 16, 2014

Hi, I am facing an issues with module unloading, I have two modules say A, B A depends on B, so B is automatically loaded when A is loaded. B module is also directly being used by the user side code via misc interface. Now when I am unloading module A, via "modprobe -r A" it is also unloading the module B which is being used by the application and resulting in the kernel crash. Also, lsmod ouput shows driver B is not used by anybody. Seems "Used By" of lsmod output is not getting updated. How to prevent unloading of module B in used. When unloading module 'A' via modprobe -r Thanks, Chetan Nanda

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