Messages in this thread | | | Date | Fri, 23 Mar 2012 02:05:21 +0400 | From | Konstantin Khlebnikov <> | Subject | Re: [PATCH 00/16] mm: prepare for converting vm->vm_flags to 64-bit |
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Andrew Morton wrote: > On Thu, 22 Mar 2012 21:28:11 +0000 > Al Viro<viro@ZenIV.linux.org.uk> wrote: > >> On Thu, Mar 22, 2012 at 02:26:47PM -0700, Andrew Morton wrote: >>> It would be nice to find some way of triggering compiler warnings or >>> sparse warnings if someone mixes a 32-bit type with a vm_flags_t. Any >>> thoughts on this? >>> >>> (Maybe that's what __nocast does, but Documentation/sparse.txt doesn't >>> describe it) >> >> Use __bitwise for that - check how gfp_t is handled. > > So what does __nocast do?
Actually it forbid any non-forced casts, but its implementation in sparse seems buggy: __nocast generates some strange false positives. For example it sometimes forgot about type attributes in function arguments, I saw this for vm_flags argument in ksm_madvise(). I can reproduce this bug, if somebody interested.
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