docs: Update documentation for stderr (now log) tracing backend.

[mirror_qemu.git] / exec.c

diff --git a/exec.c b/exec.c
index f09dd4e9284a54c83a746351646bb4458c4a4480..f46e5968189387a8bcd35d0d2751149eaa1762e2 100644 (file)
--- a/exec.c
+++ b/exec.c
@@ -17,11 +17,12 @@
  * License along with this library; if not, see <http://www.gnu.org/licenses/>.
  */
 #include "qemu/osdep.h"
+#include "qapi/error.h"
 #ifndef _WIN32
 #include <sys/mman.h>
 #endif
 
-#include "qemu-common.h"
+#include "qemu/cutils.h"
 #include "cpu.h"
 #include "tcg.h"
 #include "hw/hw.h"
@@ -1228,92 +1229,83 @@ void qemu_mutex_unlock_ramlist(void)
 }
 
 #ifdef __linux__
-
-#include <sys/vfs.h>
-
-#define HUGETLBFS_MAGIC       0x958458f6
-
-static long gethugepagesize(const char *path, Error **errp)
-{
-    struct statfs fs;
-    int ret;
-
-    do {
-        ret = statfs(path, &fs);
-    } while (ret != 0 && errno == EINTR);
-
-    if (ret != 0) {
-        error_setg_errno(errp, errno, "failed to get page size of file %s",
-                         path);
-        return 0;
-    }
-
-    return fs.f_bsize;
-}
-
 static void *file_ram_alloc(RAMBlock *block,
                             ram_addr_t memory,
                             const char *path,
                             Error **errp)
 {
-    struct stat st;
+    bool unlink_on_error = false;
     char *filename;
     char *sanitized_name;
     char *c;
     void *area;
-    int fd;
-    uint64_t hpagesize;
-    Error *local_err = NULL;
-
-    hpagesize = gethugepagesize(path, &local_err);
-    if (local_err) {
-        error_propagate(errp, local_err);
-        goto error;
-    }
-    block->mr->align = hpagesize;
-
-    if (memory < hpagesize) {
-        error_setg(errp, "memory size 0x" RAM_ADDR_FMT " must be equal to "
-                   "or larger than huge page size 0x%" PRIx64,
-                   memory, hpagesize);
-        goto error;
-    }
+    int fd = -1;
+    int64_t page_size;
 
     if (kvm_enabled() && !kvm_has_sync_mmu()) {
         error_setg(errp,
                    "host lacks kvm mmu notifiers, -mem-path unsupported");
-        goto error;
+        return NULL;
     }
 
-    if (!stat(path, &st) && S_ISDIR(st.st_mode)) {
-        /* Make name safe to use with mkstemp by replacing '/' with '_'. */
-        sanitized_name = g_strdup(memory_region_name(block->mr));
-        for (c = sanitized_name; *c != '\0'; c++) {
-            if (*c == '/') {
-                *c = '_';
-            }
+    for (;;) {
+        fd = open(path, O_RDWR);
+        if (fd >= 0) {
+            /* @path names an existing file, use it */
+            break;
         }
+        if (errno == ENOENT) {
+            /* @path names a file that doesn't exist, create it */
+            fd = open(path, O_RDWR | O_CREAT | O_EXCL, 0644);
+            if (fd >= 0) {
+                unlink_on_error = true;
+                break;
+            }
+        } else if (errno == EISDIR) {
+            /* @path names a directory, create a file there */
+            /* Make name safe to use with mkstemp by replacing '/' with '_'. */
+            sanitized_name = g_strdup(memory_region_name(block->mr));
+            for (c = sanitized_name; *c != '\0'; c++) {
+                if (*c == '/') {
+                    *c = '_';
+                }
+            }
 
-        filename = g_strdup_printf("%s/qemu_back_mem.%s.XXXXXX", path,
-                                   sanitized_name);
-        g_free(sanitized_name);
+            filename = g_strdup_printf("%s/qemu_back_mem.%s.XXXXXX", path,
+                                       sanitized_name);
+            g_free(sanitized_name);
 
-        fd = mkstemp(filename);
-        if (fd >= 0) {
-            unlink(filename);
+            fd = mkstemp(filename);
+            if (fd >= 0) {
+                unlink(filename);
+                g_free(filename);
+                break;
+            }
+            g_free(filename);
         }
-        g_free(filename);
-    } else {
-        fd = open(path, O_RDWR | O_CREAT, 0644);
+        if (errno != EEXIST && errno != EINTR) {
+            error_setg_errno(errp, errno,
+                             "can't open backing store %s for guest RAM",
+                             path);
+            goto error;
+        }
+        /*
+         * Try again on EINTR and EEXIST.  The latter happens when
+         * something else creates the file between our two open().
+         */
     }
 
-    if (fd < 0) {
-        error_setg_errno(errp, errno,
-                         "unable to create backing store for hugepages");
+    page_size = qemu_fd_getpagesize(fd);
+    block->mr->align = page_size;
+
+    if (memory < page_size) {
+        error_setg(errp, "memory size 0x" RAM_ADDR_FMT " must be equal to "
+                   "or larger than page size 0x%" PRIx64,
+                   memory, page_size);
         goto error;
     }
 
-    memory = ROUND_UP(memory, hpagesize);
+    memory = ROUND_UP(memory, page_size);
 
     /*
      * ftruncate is not supported by hugetlbfs in older
@@ -1325,11 +1317,10 @@ static void *file_ram_alloc(RAMBlock *block,
         perror("ftruncate");
     }
 
-    area = qemu_ram_mmap(fd, memory, hpagesize, block->flags & RAM_SHARED);
+    area = qemu_ram_mmap(fd, memory, page_size, block->flags & RAM_SHARED);
     if (area == MAP_FAILED) {
         error_setg_errno(errp, errno,
-                         "unable to map backing store for hugepages");
-        close(fd);
+                         "unable to map backing store for guest RAM");
         goto error;
     }
 
@@ -1341,6 +1332,12 @@ static void *file_ram_alloc(RAMBlock *block,
     return area;
 
 error:
+    if (unlink_on_error) {
+        unlink(path);
+    }
+    if (fd != -1) {
+        close(fd);
+    }
     return NULL;
 }
 #endif
@@ -1594,6 +1591,7 @@ static void ram_block_add(RAMBlock *new_block, Error **errp)
             if (err) {
                 error_propagate(errp, err);
                 qemu_mutex_unlock_ramlist();
+                return;
             }
         } else {
             new_block->host = phys_mem_alloc(new_block->max_length,
@@ -1603,6 +1601,7 @@ static void ram_block_add(RAMBlock *new_block, Error **errp)
                                  "cannot set up guest memory '%s'",
                                  memory_region_name(new_block->mr));
                 qemu_mutex_unlock_ramlist();
+                return;
             }
             memory_try_enable_merging(new_block->host, new_block->max_length);
         }