Messages in this thread | | | Subject | Re: [PATCH 4/8] i386: bitops: Kill volatile-casting of memory addresses | From | Benjamin Herrenschmidt <> | Date | Tue, 24 Jul 2007 19:49:03 +1000 |
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> The "const volatile" is so that you can pass an arbitrary pointer. The > only kind of abritraty pointer is "const volatile". > > In other words, the "volatile" has nothing at all to do with whether the > memory is volatile or not (the same way "const" has nothing to do with it: > it's purely a C type *safety* issue, exactly the same way "const" is a > type safety issue. > > A "const" on a pointer doesn't mean that the thing it points to cannot > change. When you pass a source pointer to "strlen()", it doesn't have to > be constant. But "strlen()" takes a "const" pointer, because it work son > constant pointers *too*.
However... What about that:
- This "volatile" will allow to pass pointers to volatile data to the bitops.
- Most users of "volatile" in the kenrel (except maybe jiffies) are bogus
- Thus let's remove it -as a type safety thing- to catch more of those stupid volatile that shouldn't be ? :-)
Besides, as Nick pointed out, it prevents some valid optimizations.
Cheers, Ben.
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