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Poeple keep on adding new numbered sysctls, when they're supposed not to. Add a documentation file which explain why new sysctls should use CTL_UNNUMBERED. The next patch will sprinkle pointers to this throughout sysctl.c. Eric provided the text (thanks) Cc: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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962 B
Text
22 lines
962 B
Text
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Except for a few extremely rare exceptions user space applications do not use
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the binary sysctl interface. Instead everyone uses /proc/sys/... with
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readable ascii names.
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Recently the kernel has started supporting setting the binary sysctl value to
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CTL_UNNUMBERED so we no longer need to assign a binary sysctl path to allow
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sysctls to show up in /proc/sys.
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Assigning binary sysctl numbers is an endless source of conflicts in sysctl.h,
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breaking of the user space ABI (because of those conflicts), and maintenance
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problems. A complete pass through all of the sysctl users revealed multiple
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instances where the sysctl binary interface was broken and had gone undetected
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for years.
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So please do not add new binary sysctl numbers. They are unneeded and
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problematic.
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If you really need a new binary sysctl number please first merge your sysctl
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into the kernel and then as a separate patch allocate a binary sysctl number.
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(ebiederm@xmission.com, June 2007)
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