Changeset 38dc82d in mainline for kernel/generic/src/mm/backend_elf.c

Timestamp:

2016-08-31T14:16:45Z (8 years ago)

Author:

Jakub Jermar <jakub@…>

Branches:

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

Children:

346b12a2

Parents:

dc05a9a

Message:

Make page_mapping_find() return a copy rather than the actual PTE

This makes page_mapping_find() more suitable for use with lock-free data
structures such as CHT that guarantee existence of the data only for
some limited time while a condition holds (e.g. inside of a RCU-protected
critical section that must be around all CHT lookups).

File:

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

kernel/generic/src/mm/backend_elf.c

@@ -184 +184 @@
                         
                         for (j = 0; j < count; j++) {
-                                pte_t *pte;
+                                pte_t pte;
+                                bool found;
                         
                                 /*
@@ -196 +197 @@
                                 
                                 page_table_lock(area->as, false);
-                                pte = page_mapping_find(area->as,
-                                    base + P2SZ(j), false);
-                                ASSERT(pte && PTE_VALID(pte) &&
-                                    PTE_PRESENT(pte));
+                                found = page_mapping_find(area->as,
+                                    base + P2SZ(j), false, &pte);
+
+                                ASSERT(found);
+                                ASSERT(PTE_VALID(&pte));
+                                ASSERT(PTE_PRESENT(&pte));
+
                                 btree_insert(&area->sh_info->pagemap,
                                     (base + P2SZ(j)) - area->base,
-                                    (void *) PTE_GET_FRAME(pte), NULL);
+                                    (void *) PTE_GET_FRAME(&pte), NULL);
                                 page_table_unlock(area->as, false);
 
-                                pfn_t pfn = ADDR2PFN(PTE_GET_FRAME(pte));
+                                pfn_t pfn = ADDR2PFN(PTE_GET_FRAME(&pte));
                                 frame_reference_add(pfn);
                         }
@@ -335 +339 @@
                         dirty = true;
                 } else {
-                        pte_t *pte = page_mapping_find(AS_KERNEL,
-                            base + i * FRAME_SIZE, true);
-
-                        ASSERT(pte);
-                        ASSERT(PTE_PRESENT(pte));
-
-                        frame = PTE_GET_FRAME(pte);
+                        pte_t pte;
+                        bool found;
+
+                        found = page_mapping_find(AS_KERNEL,
+                            base + i * FRAME_SIZE, true, &pte);
+
+                        ASSERT(found);
+                        ASSERT(PTE_PRESENT(&pte));
+
+                        frame = PTE_GET_FRAME(&pte);
                 }       
         } else if (upage >= start_anon) {