Re: sys_kcmp (was: Re: [PATCH 1/2] ARM: add finit_module syscall to ARM)
From: Andrew Morton <akpm@linux-foundation.org>
Date: 2012-09-22 18:40:40
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On Sat, 22 Sep 2012 14:20:46 +0100 Russell King [off-list ref] wrote:
On Sat, Sep 22, 2012 at 03:45:49PM +0400, Cyrill Gorcunov wrote:quoted
On Sat, Sep 22, 2012 at 12:56:42PM +0200, Geert Uytterhoeven wrote:quoted
On Fri, Sep 21, 2012 at 6:51 PM, Russell King [off-list ref] wrote:quoted
That brings up another question though - when was kcmp added to x86, and why aren't we getting notifications from checksyscalls.sh that ARM hasn't been updated? It seems to be that the script was broken, and no one has noticed.It seems Heiko did notice: http://www.serverphorums.com/read.php?12,559093 Now, I'm a bit puzzled by what follows: Heiko proposes a patch to ignore sys_kcmp, as it's x86-specific, which is acked by Cyrill. Then it suddenlyhpa@ pointed that better approach is to implement kcmp on other archs after i've acked the patch. so then Heiko provided a patch for s390.I discussed with hpa yesterday, and it seems the situation is as follows: 1. There exists a patch to fix checksyscalls.sh, and it's allegedly sitting in akpm's tree, and no one knows why it's just sitting there and hasn't been merged upstream.
People sometimes just reply to my commit emails, ignoring the reply-to:lkml and the "Before you just go and hit reply" request. I could start cc'ing the lists like tip-bot, but that seems a bit noisy.
2. There allegedly exists a patch to remove x86isms from sys_kcmp - allegedly also in akpm's tree. However, I've looked through the code in mainline, and nothing stands out. Ralf Beachle also said yesterday that he has looked through from the MIPS PoV and also can't see any x86isms, so we're both thinking that it should merely have the x86 dependency removed.
http://ozlabs.org/~akpm/mmotm/broken-out/syscalls-make-kcmp-syscall-available-for-all-architectures.patch I have that queued for 3.7. There is of course a little risk here. We do have a test in tools/testing/selftests/kcmp/ - I suggest that arch people run it! In fact all the tools/testing/selftests should execute successfully on all architectures - if not, please let's fix things up.
3. Until the x86 dependency is gone (that depends on what akpm proposes to do with the patches he's allegedly sitting on), non-x86 arches can only reserve the syscall, and add an IGNORE for it. Maybe akpm can provide some input to this thread, and let us know what the intentions are for checksyscalls.sh and kernel/kcmp.c, and whether he does indeed have outstanding patches for these. It would be good to at least get checksyscalls.sh fixed so arch maintainers get their warnings for new syscalls back.
http://ozlabs.org/~akpm/mmotm/broken-out/checksyscalls-fix-here-document-handling.patch I had it queued for 3.7. I now see that was a mistake and I'll get it into 3.6.