Changeset 38dc82d in mainline for kernel/generic/src/mm/as.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/as.c (modified) (6 diffs)

kernel/generic/src/mm/as.c

@@ -888 +888 @@
                 
                                 for (; i < node_size; i++) {
-                                        pte_t *pte = page_mapping_find(as,
-                                            ptr + P2SZ(i), false);
+                                        pte_t pte;
+                                        bool found = page_mapping_find(as,
+                                            ptr + P2SZ(i), false, &pte);
                                         
-                                        ASSERT(pte);
-                                        ASSERT(PTE_VALID(pte));
-                                        ASSERT(PTE_PRESENT(pte));
+                                        ASSERT(found);
+                                        ASSERT(PTE_VALID(&pte));
+                                        ASSERT(PTE_PRESENT(&pte));
                                         
                                         if ((area->backend) &&
@@ -899 +900 @@
                                                 area->backend->frame_free(area,
                                                     ptr + P2SZ(i),
-                                                    PTE_GET_FRAME(pte));
+                                                    PTE_GET_FRAME(&pte));
                                         }
                                         
@@ -1002 +1003 @@
                         
                         for (size = 0; size < (size_t) node->value[i]; size++) {
-                                pte_t *pte = page_mapping_find(as,
-                                     ptr + P2SZ(size), false);
+                                pte_t pte;
+                                bool found = page_mapping_find(as,
+                                     ptr + P2SZ(size), false, &pte);
                                 
-                                ASSERT(pte);
-                                ASSERT(PTE_VALID(pte));
-                                ASSERT(PTE_PRESENT(pte));
+                                ASSERT(found);
+                                ASSERT(PTE_VALID(&pte));
+                                ASSERT(PTE_PRESENT(&pte));
                                 
                                 if ((area->backend) &&
@@ -1013 +1015 @@
                                         area->backend->frame_free(area,
                                             ptr + P2SZ(size),
-                                            PTE_GET_FRAME(pte));
+                                            PTE_GET_FRAME(&pte));
                                 }
                                 
@@ -1314 +1316 @@
                         
                         for (size = 0; size < (size_t) node->value[i]; size++) {
-                                pte_t *pte = page_mapping_find(as,
-                                    ptr + P2SZ(size), false);
+                                pte_t pte;
+                                bool found = page_mapping_find(as,
+                                    ptr + P2SZ(size), false, &pte);
                                 
-                                ASSERT(pte);
-                                ASSERT(PTE_VALID(pte));
-                                ASSERT(PTE_PRESENT(pte));
+                                ASSERT(found);
+                                ASSERT(PTE_VALID(&pte));
+                                ASSERT(PTE_PRESENT(&pte));
                                 
-                                old_frame[frame_idx++] = PTE_GET_FRAME(pte);
+                                old_frame[frame_idx++] = PTE_GET_FRAME(&pte);
                                 
                                 /* Remove old mapping */
@@ -1451 +1454 @@
          * we need to make sure the mapping has not been already inserted.
          */
-        pte_t *pte;
-        if ((pte = page_mapping_find(AS, page, false))) {
-                if (PTE_PRESENT(pte)) {
-                        if (((access == PF_ACCESS_READ) && PTE_READABLE(pte)) ||
-                            (access == PF_ACCESS_WRITE && PTE_WRITABLE(pte)) ||
-                            (access == PF_ACCESS_EXEC && PTE_EXECUTABLE(pte))) {
+        pte_t pte;
+        bool found = page_mapping_find(AS, page, false, &pte);
+        if (found) {
+                if (PTE_PRESENT(&pte)) {
+                        if (((access == PF_ACCESS_READ) && PTE_READABLE(&pte)) ||
+                            (access == PF_ACCESS_WRITE && PTE_WRITABLE(&pte)) ||
+                            (access == PF_ACCESS_EXEC && PTE_EXECUTABLE(&pte))) {
                                 page_table_unlock(AS, false);
                                 mutex_unlock(&area->lock);