Kyle Moffett <[email protected]> writes:
> On Oct 23, 2006, at 03:25:13, Eric W. Biederman wrote:
>> --- a/fs/lockd/svc.c
>> -/* Something that isn't CTL_ANY, CTL_NONE or a value that may clash. */
>> -#define CTL_UNNUMBERED -2
>> -
>
>> --- a/fs/nfs/sysctl.c
>> -/*
>> - * Something that isn't CTL_ANY, CTL_NONE or a value that may clash.
>> - * Use the same values as fs/lockd/svc.c
>> - */
>> -#define CTL_UNNUMBERED -2
>
>> +++ b/include/linux/sysctl.h
>> #ifdef __KERNEL__
>> #define CTL_ANY -1 /* Matches any name */
>> #define CTL_NONE 0
>> +#define CTL_UNNUMBERED CTL_NONE /* sysctl without a binary number */
>> #endif
>
> This change looks totally broken. Before this patch, CTL_UNNUMBERED == -2, a
> number that isn't CTL_ANY, CTL_NONE, or a valid sysctl number. After this
> patch, CTL_UNNUMBERED == 0, or CTL_NONE.
Exactly. The only reserved sysctl numbers we have are 0 and -1.
Until my previous patch there was on number you could place into the
sysctl table that meant we did not have a binary sysctl name. 0 was
the closest but since it terminated the table it is generally useless.
-2 was a hack attempting to implement that within in the confines of
the previous sysctl implementation.
Now that I have reserved ctl_name == 0 to explicitly mean no sysctl number
and require both ctl_name == 0 and procname == NULL to terminate a sysctl
table. We can remove the hack that nfs had, because we actually have a clean
way of implementing it.
There are sysctl tables currently in existence that use -2 as the index
of a data entry so that was out. Numbers around MIN_INT/MAX_INT are probably
still available to reserve for a new purpose globally but 0 seems perfectly
up to the job.
I kept the CTL_UNNUMBERED name because it seems a little clearer than CTL_NONE.
Eric
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