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Changeset de73242 in mainline


Ignore:
Timestamp:
2012-07-23T08:06:18Z (9 years ago)
Author:
Jakub Jermar <jakub@…>
Branches:
lfn, master
Children:
efdfebc
Parents:
e943ecf
Message:

Comment the purpose of the recently added barriers.

Location:
kernel/genarch/src/mm
Files:
2 edited

Legend:

Unmodified
Added
Removed
  • kernel/genarch/src/mm/page_ht.c

    re943ecf rde73242  
    209209                pte->frame = ALIGN_DOWN(frame, FRAME_SIZE);
    210210
     211                /*
     212                 * Make sure that a concurrent ht_mapping_find() will see the
     213                 * new entry only after it is fully initialized.
     214                 */
    211215                write_barrier();
    212216               
  • kernel/genarch/src/mm/page_pt.c

    re943ecf rde73242  
    8989                    PAGE_NOT_PRESENT | PAGE_USER | PAGE_EXEC | PAGE_CACHEABLE |
    9090                    PAGE_WRITE);
     91                /*
     92                 * Make sure that a concurrent hardware page table walk or
     93                 * pt_mapping_find() will see the new PTL1 only after it is
     94                 * fully initialized.
     95                 */
    9196                write_barrier();
    9297                SET_PTL1_PRESENT(ptl0, PTL0_INDEX(page));
     
    103108                    PAGE_NOT_PRESENT | PAGE_USER | PAGE_EXEC | PAGE_CACHEABLE |
    104109                    PAGE_WRITE);
     110                /*
     111                 * Make the new PTL2 visible only after it is fully initialized.
     112                 */
    105113                write_barrier();
    106114                SET_PTL2_PRESENT(ptl1, PTL1_INDEX(page));       
     
    117125                    PAGE_NOT_PRESENT | PAGE_USER | PAGE_EXEC | PAGE_CACHEABLE |
    118126                    PAGE_WRITE);
     127                /*
     128                 * Make the new PTL3 visible only after it is fully initialized.
     129                 */
    119130                write_barrier();
    120131                SET_PTL3_PRESENT(ptl2, PTL2_INDEX(page));
     
    125136        SET_FRAME_ADDRESS(ptl3, PTL3_INDEX(page), frame);
    126137        SET_FRAME_FLAGS(ptl3, PTL3_INDEX(page), flags | PAGE_NOT_PRESENT);
     138        /*
     139         * Make the new mapping visible only after it is fully initialized.
     140         */
    127141        write_barrier();
    128142        SET_FRAME_PRESENT(ptl3, PTL3_INDEX(page));
     
    296310
    297311#if (PTL1_ENTRIES != 0)
     312        /*
     313         * Always read ptl2 only after we are sure it is present.
     314         */
    298315        read_barrier();
    299316#endif
     
    304321
    305322#if (PTL2_ENTRIES != 0)
     323        /*
     324         * Always read ptl3 only after we are sure it is present.
     325         */
    306326        read_barrier();
    307327#endif
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