On Tue, Mar 01, 2016 at 05:19:40PM +0000, Paul Burton wrote: > > >+static inline void set_pte_at(struct mm_struct *mm, unsigned long addr, > > >+ pte_t *ptep, pte_t pteval) > > >+{ > > >+ extern void __update_cache(unsigned long address, pte_t pte); > > >+ > > >+ if (!pte_present(pteval)) > > >+ goto cache_sync_done; > > >+ > > >+ if (pte_present(*ptep) && (pte_pfn(*ptep) == pte_pfn(pteval))) > > >+ goto cache_sync_done; > > >+ > > >+ __update_cache(addr, pteval); > > >+cache_sync_done: > > >+ set_pte(ptep, pteval); > > >+} > > >+ > > > > This seems crazy. > > Perhaps, but also correct... > > > I don't think any other architecture does this type of work in set_pte_at(). > > Yes they do. As mentioned in the commit message see arm, ia64 or powerpc > for architectures that all do the same sort of thing in set_pte_at. > > > Can you look into finding a better way? > > Not that I can see. FYI, this is the original commit message adding set_pte_at(). The commit predates Linus' git history but is in the various history trees, for example https://git.kernel.org/cgit/linux/kernel/git/tglx/history.git/commit/?id=ae3d0a847f4b38812241e4a5dc3371965c752a8c Or for your convenience: commit ae3d0a847f4b38812241e4a5dc3371965c752a8c Author: David S. Miller <davem@xxxxxxxxxxxxxxxxxx> Date: Tue Feb 22 23:42:56 2005 -0800 [MM]: Add set_pte_at() which takes 'mm' and 'addr' args. I'm taking a slightly different approach this time around so things are easier to integrate. Here is the first patch which builds the infrastructure. Basically: 1) Add set_pte_at() which is set_pte() with 'mm' and 'addr' arguments added. All generic code uses set_pte_at(). Most platforms simply get this define: #define set_pte_at(mm,addr,ptep,pteval) set_pte(ptep,pteval) I chose this method over simply changing all set_pte() call sites because many platforms implement this in assembler and it would take forever to preserve the build and stabilize things if modifying that was necessary. Soon, with platform maintainer's help, we can kill of set_pte() entirely. To be honest, there are only a handful of set_pte() call sites in the arch specific code. Actually, in this patch ppc64 is completely set_pte() free and does not define it. 2) pte_clear() gets 'mm' and 'addr' arguments now. This had a cascading effect on many ptep_test_and_*() routines. Specifically: a) ptep_test_and_clear_{young,dirty}() now take 'vma' and 'address' args. b) ptep_get_and_clear now take 'mm' and 'address' args. c) ptep_mkdirty was deleted, unused by any code. d) ptep_set_wrprotect now takes 'mm' and 'address' args. I've tested this patch as follows: 1) compile and run tested on sparc64/SMP 2) compile tested on: a) ppc64/SMP b) i386 both with and without PAE enabled Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Which doesn't specify if the function is meant for cache management nor is it documented in Documentation/cachetlb.txt. Ralf -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html