(nuttx) branch master updated: fs/shm/shmfs_alloc.c: Allocate zero-initialized memory in flat build

[xiaoxiang]

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xiaoxiang pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/nuttx.git


The following commit(s) were added to refs/heads/master by this push:
     new 366977b767 fs/shm/shmfs_alloc.c: Allocate zero-initialized memory in 
flat build
366977b767 is described below

commit 366977b76737ee441eec09461152bf9883a19bbb
Author: Jukka Laitinen <juk...@ssrc.tii.ae>
AuthorDate: Thu Dec 12 12:22:39 2024 +0200

    fs/shm/shmfs_alloc.c: Allocate zero-initialized memory in flat build
    
    POSIX requires that the shm objects are zero-initialized. This has been 
broken
    in some earlier commits (starting from 
9af5fc5d09724a5d300bc07ce85b9ba5c01ffadd)
    
    Also fix the flat build memory allocation to allocate both object data and 
payload
    in the same chunk (as the comment also suggests). This saves allocations 
and memory
    in a system with lots of shm objects.
    
    Signed-off-by: Jukka Laitinen <juk...@ssrc.tii.ae>
---
 fs/shm/shmfs_alloc.c | 50 +++++++++++++++++++++++++++-----------------------
 1 file changed, 27 insertions(+), 23 deletions(-)

diff --git a/fs/shm/shmfs_alloc.c b/fs/shm/shmfs_alloc.c
index 4764c901e6..7b68b763cf 100644
--- a/fs/shm/shmfs_alloc.c
+++ b/fs/shm/shmfs_alloc.c
@@ -51,24 +51,26 @@ FAR struct shmfs_object_s *shmfs_alloc_object(size_t length)
    * chunk in kernel heap
    */
 
-  object = fs_heap_zalloc(sizeof(struct shmfs_object_s));
-  if (object)
+  size_t hdr_size = sizeof(struct shmfs_object_s);
+  size_t alloc_size = length;
+  size_t cachesize = up_get_dcache_linesize();
+
+  if (cachesize > 0)
     {
-      size_t cachesize = up_get_dcache_linesize();
-      if (cachesize > 0)
-        {
-          object->paddr = fs_heap_memalign(cachesize,
-                                           ALIGN_UP(length, cachesize));
-        }
-      else
-        {
-          object->paddr = fs_heap_malloc(length);
-        }
+      hdr_size = ALIGN_UP(hdr_size, cachesize);
+      alloc_size = ALIGN_UP(alloc_size, cachesize);
+      object = fs_heap_memalign(cachesize, hdr_size + alloc_size);
+    }
+  else
+    {
+      object = fs_heap_malloc(hdr_size + alloc_size);
+    }
 
-      if (object->paddr)
-        {
-           allocated = true;
-        }
+  if (object)
+    {
+      memset(object, 0, hdr_size + alloc_size);
+      object->paddr = (void *)((uintptr_t)object + hdr_size);
+      allocated = true;
     }
 
 #elif defined(CONFIG_BUILD_PROTECTED)
@@ -76,23 +78,27 @@ FAR struct shmfs_object_s *shmfs_alloc_object(size_t length)
    * memory in user heap
    */
 
+  size_t alloc_size = length;
+
   object = fs_heap_zalloc(sizeof(struct shmfs_object_s));
   if (object)
     {
       size_t cachesize = up_get_dcache_linesize();
+
       if (cachesize > 0)
         {
-          object->paddr = kumm_memalign(cachesize,
-                                        ALIGN_UP(length, cachesize));
+          alloc_size = ALIGN_UP(alloc_size, cachesize);
+          object->paddr = kumm_memalign(cachesize, alloc_size);
         }
       else
         {
-          object->paddr = kumm_malloc(length);
+          object->paddr = kumm_malloc(alloc_size);
         }
 
       if (object->paddr)
         {
-           allocated = true;
+          memset(object->paddr, 0, alloc_size);
+          allocated = true;
         }
     }
 
@@ -152,9 +158,7 @@ void shmfs_free_object(FAR struct shmfs_object_s *object)
 {
   if (object)
     {
-#if defined(CONFIG_BUILD_FLAT)
-      fs_heap_free(object->paddr);
-#elif defined(CONFIG_BUILD_PROTECTED)
+#if defined(CONFIG_BUILD_PROTECTED)
       kumm_free(object->paddr);
 #elif defined(CONFIG_BUILD_KERNEL)
       size_t i;