[Qemu-devel] [PATCH v2 3/4] memory-backend-file: improve error handling

[Hu Tao]

This patch fixes two problems of memory-backend-file:

1. If user adds a memory-backend-file object using object_add command,
   specifying a non-existing directory for property mem-path, qemu
   will core dump with message:

     /nonexistingdir: No such file or directory
     Bad ram offset fffffffffffff000
     Aborted (core dumped)

2. If user adds a memory-backend-file object using object_add command,
   specifying a size that is less than huge page size, qemu
   will core dump with message:

     Bad ram offset fffffffffffff000
     Aborted (core dumped)

Signed-off-by: Hu Tao <hu...@cn.fujitsu.com>
---
 exec.c | 26 ++++++++++++++++++--------
 1 file changed, 18 insertions(+), 8 deletions(-)

diff --git a/exec.c b/exec.c
index 8705cc5..a6afb4d 100644
--- a/exec.c
+++ b/exec.c
@@ -997,7 +997,7 @@ void qemu_mutex_unlock_ramlist(void)
 
 #define HUGETLBFS_MAGIC       0x958458f6
 
-static long gethugepagesize(const char *path)
+static long gethugepagesize(const char *path, Error **errp)
 {
     struct statfs fs;
     int ret;
@@ -1007,7 +1007,7 @@ static long gethugepagesize(const char *path)
     } while (ret != 0 && errno == EINTR);
 
     if (ret != 0) {
-        perror(path);
+        error_setg_errno(errp, errno, "failed to stat file %s", path);
         return 0;
     }
 
@@ -1025,17 +1025,19 @@ static void *file_ram_alloc(RAMBlock *block,
     char *filename;
     char *sanitized_name;
     char *c;
-    void *area;
+    void *area = NULL;
     int fd;
     unsigned long hpagesize;
 
-    hpagesize = gethugepagesize(path);
+    hpagesize = gethugepagesize(path, errp);
     if (!hpagesize) {
         goto error;
     }
 
     if (memory < hpagesize) {
-        return NULL;
+        error_setg(errp, "memory size " RAM_ADDR_FMT " should be larger "
+                   "than huge page size %" PRIx64, memory, hpagesize);
+        goto error;
     }
 
     if (kvm_enabled() && !kvm_has_sync_mmu()) {
@@ -1095,8 +1097,8 @@ static void *file_ram_alloc(RAMBlock *block,
     return area;
 
 error:
-    if (mem_prealloc) {
-        exit(1);
+    if (area && area != MAP_FAILED) {
+        munmap(area, memory);
     }
     return NULL;
 }
@@ -1279,6 +1281,7 @@ ram_addr_t qemu_ram_alloc_from_file(ram_addr_t size, 
MemoryRegion *mr,
                                     Error **errp)
 {
     RAMBlock *new_block;
+    ram_addr_t addr;
 
     if (xen_enabled()) {
         error_setg(errp, "-mem-path not supported with Xen\n");
@@ -1308,7 +1311,14 @@ ram_addr_t qemu_ram_alloc_from_file(ram_addr_t size, 
MemoryRegion *mr,
         return -1;
     }
 
-    return ram_block_add(new_block);
+    addr = ram_block_add(new_block);
+    if (addr == -1) {
+        g_free(new_block);
+        error_setg(errp, "failed to allocate memory\n");
+        return -1;
+    }
+
+    return addr;
 }
 #endif
 
-- 
1.9.3