Changeset d67dfdc in mainline for kernel/generic/src/mm/as.c

Timestamp:

2012-05-12T09:34:40Z (13 years ago)

Author:

Jakub Jermar <jakub@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

306f0de

Parents:

8d2d308f

Message:

Avoid blocking callpaths in TLB shootdown sequences.

• In as_area_resize(), the TLB shootdown sequence should not involve used_space_remove() as it may block when waiting for memory.

File:

• kernel/generic/src/mm/as.c (modified) (3 diffs)

kernel/generic/src/mm/as.c

@@ -665 +665 @@
                 
                 page_table_lock(as, false);
-                
-                /*
-                 * Start TLB shootdown sequence.
-                 */
-                ipl_t ipl = tlb_shootdown_start(TLB_INVL_PAGES, as->asid,
-                    area->base + P2SZ(pages), area->pages - pages);
                 
                 /*
@@ -726 +720 @@
                                 }
                                 
+                                /*
+                                 * Start TLB shootdown sequence.
+                                 *
+                                 * The sequence is rather short and can be
+                                 * repeated multiple times. The reason is that
+                                 * we don't want to have used_space_remove()
+                                 * inside the sequence as it may use a blocking
+                                 * memory allocation for its B+tree. Blocking
+                                 * while holding the tlblock spinlock is
+                                 * forbidden and would hit a kernel assertion.
+                                 */
+
+                                ipl_t ipl = tlb_shootdown_start(TLB_INVL_PAGES,
+                                    as->asid, area->base + P2SZ(pages),
+                                    area->pages - pages);
+                
                                 for (; i < size; i++) {
                                         pte_t *pte = page_mapping_find(as,
@@ -743 +753 @@
                                         page_mapping_remove(as, ptr + P2SZ(i));
                                 }
+                
+                                /*
+                                 * Finish TLB shootdown sequence.
+                                 */
+                
+                                tlb_invalidate_pages(as->asid,
+                                    area->base + P2SZ(pages),
+                                    area->pages - pages);
+                
+                                /*
+                                 * Invalidate software translation caches
+                                 * (e.g. TSB on sparc64, PHT on ppc32).
+                                 */
+                                as_invalidate_translation_cache(as,
+                                    area->base + P2SZ(pages),
+                                    area->pages - pages);
+                                tlb_shootdown_finalize(ipl);
                         }
                 }
-                
-                /*
-                 * Finish TLB shootdown sequence.
-                 */
-                
-                tlb_invalidate_pages(as->asid, area->base + P2SZ(pages),
-                    area->pages - pages);
-                
-                /*
-                 * Invalidate software translation caches
-                 * (e.g. TSB on sparc64, PHT on ppc32).
-                 */
-                as_invalidate_translation_cache(as, area->base + P2SZ(pages),
-                    area->pages - pages);
-                tlb_shootdown_finalize(ipl);
-                
                 page_table_unlock(as, false);
         } else {