Fix: sync buffer file metadata on buffer allocation

[lttng-ust.git] / libringbuffer / shm.c

diff --git a/libringbuffer/shm.c b/libringbuffer/shm.c
index 53b2b6ec3f1819ba69d2b328f83f224d1d0b220d..8ac321e3931906888f79dd9e2419a7dbca8225de 100644 (file)
--- a/libringbuffer/shm.c
+++ b/libringbuffer/shm.c
@@ -18,6 +18,7 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
+#define _LGPL_SOURCE
 #include "shm.h"
 #include <unistd.h>
 #include <fcntl.h>
@@ -32,11 +33,15 @@
 #include <lttng/align.h>
 #include <limits.h>
 #include <helper.h>
+#include <ust-fd.h>
 
 /*
  * Ensure we have the required amount of space available by writing 0
  * into the entire buffer. Not doing so can trigger SIGBUS when going
  * beyond the available shm space.
+ *
+ * Also ensure the file metadata is synced with the storage by using
+ * fsync(2).
  */
 static
 int zero_file(int fd, size_t len)
@@ -65,6 +70,11 @@ int zero_file(int fd, size_t len)
                }
                written += retlen;
        }
+       ret = fsync(fd);
+       if (ret) {
+               ret = (int) -errno;
+               goto error;
+       }
        ret = 0;
 error:
        free(zeropage);
@@ -342,7 +352,7 @@ error_fcntl:
 }
 
 static
-void shmp_object_destroy(struct shm_object *obj)
+void shmp_object_destroy(struct shm_object *obj, int consumer)
 {
        switch (obj->type) {
        case SHM_OBJECT_SHM:
@@ -354,20 +364,46 @@ void shmp_object_destroy(struct shm_object *obj)
                        PERROR("umnmap");
                        assert(0);
                }
+
                if (obj->shm_fd_ownership) {
-                       ret = close(obj->shm_fd);
-                       if (ret) {
-                               PERROR("close");
-                               assert(0);
+                       /* Delete FDs only if called from app (not consumer). */
+                       if (!consumer) {
+                               lttng_ust_lock_fd_tracker();
+                               ret = close(obj->shm_fd);
+                               if (!ret) {
+                                       lttng_ust_delete_fd_from_tracker(obj->shm_fd);
+                               } else {
+                                       PERROR("close");
+                                       assert(0);
+                               }
+                               lttng_ust_unlock_fd_tracker();
+                       } else {
+                               ret = close(obj->shm_fd);
+                               if (ret) {
+                                       PERROR("close");
+                                       assert(0);
+                               }
                        }
                }
                for (i = 0; i < 2; i++) {
                        if (obj->wait_fd[i] < 0)
                                continue;
-                       ret = close(obj->wait_fd[i]);
-                       if (ret) {
-                               PERROR("close");
-                               assert(0);
+                       if (!consumer) {
+                               lttng_ust_lock_fd_tracker();
+                               ret = close(obj->wait_fd[i]);
+                               if (!ret) {
+                                       lttng_ust_delete_fd_from_tracker(obj->wait_fd[i]);
+                               } else {
+                                       PERROR("close");
+                                       assert(0);
+                               }
+                               lttng_ust_unlock_fd_tracker();
+                       } else {
+                               ret = close(obj->wait_fd[i]);
+                               if (ret) {
+                                       PERROR("close");
+                                       assert(0);
+                               }
                        }
                }
                break;
@@ -379,10 +415,22 @@ void shmp_object_destroy(struct shm_object *obj)
                for (i = 0; i < 2; i++) {
                        if (obj->wait_fd[i] < 0)
                                continue;
-                       ret = close(obj->wait_fd[i]);
-                       if (ret) {
-                               PERROR("close");
-                               assert(0);
+                       if (!consumer) {
+                               lttng_ust_lock_fd_tracker();
+                               ret = close(obj->wait_fd[i]);
+                               if (!ret) {
+                                       lttng_ust_delete_fd_from_tracker(obj->wait_fd[i]);
+                               } else {
+                                       PERROR("close");
+                                       assert(0);
+                               }
+                               lttng_ust_unlock_fd_tracker();
+                       } else {
+                               ret = close(obj->wait_fd[i]);
+                               if (ret) {
+                                       PERROR("close");
+                                       assert(0);
+                               }
                        }
                }
                free(obj->memory_map);
@@ -393,12 +441,12 @@ void shmp_object_destroy(struct shm_object *obj)
        }
 }
 
-void shm_object_table_destroy(struct shm_object_table *table)
+void shm_object_table_destroy(struct shm_object_table *table, int consumer)
 {
        int i;
 
        for (i = 0; i < table->allocated_len; i++)
-               shmp_object_destroy(&table->objects[i]);
+               shmp_object_destroy(&table->objects[i], consumer);
        free(table);
 }