December 2015 - kernelnewbies@kernelnewbies.org

Trivial patches and lots of maintainers
by Manuel Pégourié-Gonnard Dec. 28, 2015

Dec. 28, 2015

Hi, When submitting trivial patches such as fixing typos in comments, should I always Cc all people suggested by get_maintainer.pl? For example, I noticed a typo in comments in drivers/base/power/common.c for which get_maintainers.pl suggests 4 individuals plus 2 mailings lists (to which I think I should add the Trivial Patch Monkey). Intuitively, it feels wrong to personally spam 4 people for such a trivial thing. OTOH, maybe it's OK because those people are used to handle a very large volume of email anyway, and they prefer to have an opportunity to see everything, no matter how trivial. What's the best usage here? Thanks, Manuel.

2 2

first patch
by maoma king Dec. 27, 2015

Dec. 27, 2015

Dear I have sent my first patch (https://lkml.org/lkml/2015/11/18/239) to linux-next tree.But I never received anything about it.So I sent it again. You say "Doesn't apply to my tree :(".but it can be apply to least linux-next branch . I make n new patch and send it.I receive review(https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1048115… . I want to know what's wrong with me? how do I know that my patch is accepted?

3 2

how to reduce both vmlinuz size and modules?
by Robert P. J. Day Dec. 27, 2015

Dec. 27, 2015

currently running latest version of fedora 23, with 4.2.8-200.fc22.x86_64 fedora kernel package, and i'm wondering about the best way to both reduce the kernel size, and cut down on the number of modules i'm building, based on what looks like combining a couple of make targets. if i start with the latest git kernel repo, it *looks* like i can use the /boot/config-4.2.8-200.fc22.x86_64 config file as a starting point, copy it in as .config, then: $ make allmodconfig $ make localmodconfig as i read it (and i could be mistaken), the first make would transform as many "y" kernel selections to "m" as possible, while the second would then remove any module config selections that are currently not loaded. am i reading that correctly? is there a simpler way to do this? rday -- ======================================================================== Robert P. J. Day Ottawa, Ontario, CANADA http://crashcourse.ca Twitter: http://twitter.com/rpjday LinkedIn: http://ca.linkedin.com/in/rpjday ========================================================================

2 3

Fwd: Re: [PATCH] allow strictatime to be set as a global default
by Raymond Jennings Dec. 25, 2015

Dec. 25, 2015

I've been cooking a very simple patch that hopefully gives both sides of the "great strictatime war" what they want with minimal pain. I sent it through kernelnewbies for a basic review and got some polish on irc. ---- Signed-off-by: Raymond Jennings <shentino(a)gmail.com> Reviewed-by: Mandeep Sandhu <mandeepsandhu.chd(a)gmail.com> diff --git a/fs/Kconfig b/fs/Kconfig index 6ce72d8..122a993 100644 --- a/fs/Kconfig +++ b/fs/Kconfig @@ -4,6 +4,20 @@ menu "File systems" +config DEFAULT_STRICTATIME + bool "Use strictatime by default" + default n + help + Use strictatime as a default mount option. + + Relatime became the default in 2007 to reduce I/O load on block devices. + + Enabling this option will restore historic behavior and provide perfectly + accurate atimes, but the increase in write load may reduce performance + and shorten the life of the block device. + + If unsure, say N. + # Use unaligned word dcache accesses config DCACHE_WORD_ACCESS bool diff --git a/fs/namespace.c b/fs/namespace.c index 0570729..48e7c15 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -2680,9 +2680,15 @@ long do_mount(const char *dev_name, const char __user *dir_name, if (retval) goto dput_out; - /* Default to relatime unless overriden */ +#ifdef CONFIG_DEFAULT_STRICTATIME + /* Default to strictatime unless overridden */ + if (flags & MS_RELATIME) + mnt_flags |= MNT_RELATIME; +#else + /* Default to relatime unless overridden */ if (!(flags & MS_NOATIME)) mnt_flags |= MNT_RELATIME; +#endif /* Separate the per-mountpoint flags */ if (flags & MS_NOSUID) ---------- Forwarded message ---------- From: Mandeep Sandhu <mandeepsandhu.chd(a)gmail.com> Subject: Re: [PATCH] allow strictatime to be set as a global default Date: Sat, 19 Dec 2015 17:25:37 -0800 To: Raymond Jennings <shentino(a)gmail.com> Cc: kernelnewbies <kernelnewbies(a)kernelnewbies.org> Looks good to me. To test the real waters....you should send it to the lists you mentioned (or whatever the maintainers script tells you). Good luck, -mandeep On Sat, Dec 19, 2015 at 1:41 PM, Raymond Jennings <shentino(a)gmail.com> wrote: > How does this version look? > > (the other delta for the other file was untouched) > > Any chance it is ready to post to the big list (presumably fs with a > cc to > lkml)? > > diff --git a/fs/Kconfig b/fs/Kconfig > index 6ce72d8..122a993 100644 > --- a/fs/Kconfig > +++ b/fs/Kconfig > @@ -4,6 +4,20 @@ > > menu "File systems" > > +config DEFAULT_STRICTATIME > + bool "Use strictatime by default" > + default n > + help > + Use strictatime as a default mount option. > + > + Relatime became the default in 2007 to reduce I/O load on block > devices. > + > + Enabling this option will restore historic behavior and provide > perfectly > + accurate atimes, but the increase in write load may reduce > performance > + and shorten the life of the block device. > + > + If unsure, say N. > + > # Use unaligned word dcache accesses > config DCACHE_WORD_ACCESS > bool > > On Fri, Dec 18, 2015 at 2:21 PM, Mandeep Sandhu > <mandeepsandhu.chd(a)gmail.com> wrote: >> >> Ah yes...now it makes sense! :) >> >> The current 'word of caution' (about increased I/O load on block >> devices), seems mild IMHO. Maybe we should we have a stricter >> warning...something like enabling this option might be harmful to >> the >> life of your block device (due to excessive writes) and will also >> lead >> to reduced performance? >> >> HTH, >> -mandeep >> >> >> On Fri, Dec 18, 2015 at 2:12 PM, Raymond Jennings >> <shentino(a)gmail.com> >> wrote: >> > On Fri, Dec 18, 2015 at 10:50 AM, Mandeep Sandhu >> > <mandeepsandhu.chd(a)gmail.com> wrote: >> >> >> >> You've removed the strictatime option altogether. So how does >> that >> >> satisfy people who _do_ want it? >> > >> > >> > ...actually it looks like I was an idiot and got my diff >> backwards when >> > I >> > pulled it out of git :P >> > >> > Here's the correct version. >> > >> > diff --git a/fs/Kconfig b/fs/Kconfig >> > index 6ce72d8..4b917eb 100644 >> > --- a/fs/Kconfig >> > +++ b/fs/Kconfig >> > @@ -4,6 +4,17 @@ >> > >> > menu "File systems" >> > >> > +config DEFAULT_STRICTATIME >> > + bool "Use strictatime by default" >> > + default n >> > + help >> > + Use strictatime as a default mount option. >> > + >> > + Strictatime preserves ancient historic behavior of >> keeping the >> > atime field always up to date. >> > + However, it was changed in 2007 to relatime to reduce >> I/O load >> > on >> > block devices. >> > + >> > + If unsure, say N. >> > + >> > # Use unaligned word dcache accesses >> > config DCACHE_WORD_ACCESS >> > bool >> > diff --git a/fs/namespace.c b/fs/namespace.c >> > index 0570729..48e7c15 100644 >> > --- a/fs/namespace.c >> > +++ b/fs/namespace.c >> > @@ -2680,9 +2680,15 @@ long do_mount(const char *dev_name, const >> char >> > __user >> > *dir_name, >> > if (retval) >> > goto dput_out; >> > >> > - /* Default to relatime unless overriden */ >> > +#ifdef CONFIG_DEFAULT_STRICTATIME >> > + /* Default to strictatime unless overridden */ >> > + if (flags & MS_RELATIME) >> > + mnt_flags |= MNT_RELATIME; >> > +#else >> > + /* Default to relatime unless overridden */ >> > if (!(flags & MS_NOATIME)) >> > mnt_flags |= MNT_RELATIME; >> > +#endif >> > >> > >> > /* Separate the per-mountpoint flags */ >> > if (flags & MS_NOSUID) >> > >> > >> > > >

1 0

what is the rationale for "uio-howto.aux.xml" DocBook file?
by Robert P. J. Day Dec. 25, 2015

Dec. 25, 2015

just noticed for the first time the in-kernel Doc file uio-howto.aux.xml (sitting next to uio-howto.xml). the latter file is the one processed by "make htmldocs", so what is the purpose of that former one? i don't see where/how it's being picked up. any hints? am i missing something painfully obvious? rday -- ======================================================================== Robert P. J. Day Ottawa, Ontario, CANADA http://crashcourse.ca Twitter: http://twitter.com/rpjday LinkedIn: http://ca.linkedin.com/in/rpjday ========================================================================

1 0

[PATCH] allow strictatime to be set as a global default
by Raymond Jennings Dec. 20, 2015

Dec. 20, 2015

I'm aware of a little tiff regarding strictatime in the past, and I think I came up with a patch that might help everyone get what they want. I'm already using it myself. I've had some review on #kernelnewbies for technical issues, how does this look? --- diff --git a/fs/Kconfig b/fs/Kconfig index 4b917eb..6ce72d8 100644 --- a/fs/Kconfig +++ b/fs/Kconfig @@ -4,17 +4,6 @@ menu "File systems" -config DEFAULT_STRICTATIME - bool "Use strictatime by default" - default n - help - Use strictatime as a default mount option. - - Strictatime preserves ancient historic behavior of keeping the atime field always up to date. - However, it was changed in 2007 to relatime to reduce I/O load on block devices. - - If unsure, say N. - # Use unaligned word dcache accesses config DCACHE_WORD_ACCESS bool diff --git a/fs/namespace.c b/fs/namespace.c index 48e7c15..0570729 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -2680,15 +2680,9 @@ long do_mount(const char *dev_name, const char __user *dir_name, if (retval) goto dput_out; -#ifdef CONFIG_DEFAULT_STRICTATIME - /* Default to strictatime unless overridden */ - if (flags & MS_RELATIME) - mnt_flags |= MNT_RELATIME; -#else - /* Default to relatime unless overridden */ + /* Default to relatime unless overriden */ if (!(flags & MS_NOATIME)) mnt_flags |= MNT_RELATIME; -#endif /* Separate the per-mountpoint flags */ if (flags & MS_NOSUID)

2 5

Customizing UIO mmap'ing
by Kenneth Adam Miller Dec. 18, 2015

Dec. 18, 2015

So, previously I think I misunderstood how to use uio_dmem_genirq. Let me explain the way I think it currently works (bare with me, I departed from looking at this driver after only about a week of looking at it): Generally uio_dmem_genirq.c builds on top of uio.c, which provides a common module basis for isolating code common to the other specific modules. But for a specific purpose, uio_dmem_genirq.c has be either customized or extended in order that specific memory regions can be set as accessible. Most easily, this is done in a first come first serve approach by filling out the details (which exactly?) left missing in uio_dmem_genirq.c, and to start, that would be in uio_of_genirq_match <https://proxy-us.hide.me/go.php?u=zWvu%2Fc4k0RUgdQesK%2F26T4EuwcXktyOuOa%2F…> . Am I correct?

2 4

Track execution of close() system call in kernel
by Harsh Jain Dec. 18, 2015

Dec. 18, 2015

Hi, How to track the code flow of close() system call for socket fds. In working case I am getting following debug traces in dmesg inet_release sk ffff88040e376000 sk->sk_prot->close ffffffffa0774a50 chelsio_close Entered CPU: 3 PID: 10108 Comm: openssl Tainted: G O 3.17.8_harsh_cry_test_dis #28 Hardware name: Supermicro X8ST3/X8ST3, BIOS 2.0 07/29/10 0000000000000000 ffff8800d87ebde8 ffffffff815e8356 ffffffff81dc21a0 ffff88040e376000 ffff8800d87ebe28 ffffffffa0774a91 ffff88040646f880 ffff88040e376000 0000000000000000 ffff8803fef299c0 ffff8803fef299f0 Call Trace: [<ffffffff815e8356>] dump_stack+0x51/0x6b [<ffffffffa0774a91>] chelsio_close+0x41/0x340 [t4_tom] [<ffffffff815966c0>] inet_release+0xc0/0xd0 [<ffffffff815030b9>] sock_release+0x29/0xa0 [<ffffffff81503582>] sock_close+0x12/0x20 [<ffffffff811bf1b0>] __fput+0xd0/0x260 [<ffffffff811bf3ee>] ____fput+0xe/0x10 [<ffffffff81089e5d>] task_work_run+0xad/0xe0 [<ffffffff81003d74>] do_notify_resume+0x84/0x90 [<ffffffff815ed8da>] int_signal+0x12/0x17 chelsio_close Exit After doing changes in kernel module dumpstack is not getting printed from "chelsio_close" function. I added function entry/exit trace in "sock_release" also. Return value of close() system call is also zero. Its executing successfully but where in kernel code? Regards Harsh Jain

1 0

Work with correct branch for kernel changes
by Shirish Gajera Dec. 17, 2015

Dec. 17, 2015

Hi, I am new to linux kernel and trying to understand the process of different git branch to work. So, if I am not wrong then there are different branch like stable, next, staging etc. Previously I work with staging branch so if I am making any changes for drivers/staging I have to work with staging branch like follow. git clone git checkout -t -b staging-testing origin/staging-testing git chekcout -b MY_LOCAL_BRANCH not do work and subimt So, how it work for other source structure, like now I want to make some for y2038 -> drivers/scsi which branch should I set up and work with, next/stable/or is there any specific y2038 branch. Any wiki link or documentation that explain this full process which branch to work with when making changes to specific directory will be useful. Thanks, Shirish

3 2

Query on freeing of new_fdt->open_fds inside src/fs/file.c
by pavi1729 Dec. 11, 2015

Dec. 11, 2015

Hi, I am unable to understand how new_fdt->open_fds can be freed in __free_fdtable when its an unsigned long in files_struct ? Details: FUNCTION: dup_fd http://lxr.free-electrons.com/source/fs/file.c#L261 LINE : 282 : new_fdt->open_fds = newf->open_fds_init; files_struct : http://lxr.free-electrons.com/source/include/linux/fdtable.h#L45 unsigned long open_fds_init[1]; Cheers, Pavi

1 0