Add channel wakeup fd to monitor close

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

diff --git a/libringbuffer/shm.c b/libringbuffer/shm.c
index 85b1e4b7e6ce9b1c4ef1fc61e04a17dfb554c85a..90160ce1976c7c7c5a2853eca93229c9b3871460 100644 (file)
--- a/libringbuffer/shm.c
+++ b/libringbuffer/shm.c
@@ -231,6 +231,7 @@ struct shm_object *_shm_object_table_alloc_mem(struct shm_object_table *table,
 {
        struct shm_object *obj;
        void *memory_map;
+       int waitfd[2], i, ret;
 
        if (table->allocated_len >= table->size)
                return NULL;
@@ -240,8 +241,28 @@ struct shm_object *_shm_object_table_alloc_mem(struct shm_object_table *table,
        if (!memory_map)
                goto alloc_error;
 
-       obj->wait_fd[0] = -1;
-       obj->wait_fd[1] = -1;
+       /* wait_fd: create pipe */
+       ret = pipe(waitfd);
+       if (ret < 0) {
+               PERROR("pipe");
+               goto error_pipe;
+       }
+       for (i = 0; i < 2; i++) {
+               ret = fcntl(waitfd[i], F_SETFD, FD_CLOEXEC);
+               if (ret < 0) {
+                       PERROR("fcntl");
+                       goto error_fcntl;
+               }
+       }
+       /* The write end of the pipe needs to be non-blocking */
+       ret = fcntl(waitfd[1], F_SETFL, O_NONBLOCK);
+       if (ret < 0) {
+               PERROR("fcntl");
+               goto error_fcntl;
+       }
+       memcpy(obj->wait_fd, waitfd, sizeof(waitfd));
+
+       /* no shm_fd */
        obj->shm_fd = -1;
 
        obj->type = SHM_OBJECT_MEM;
@@ -252,6 +273,16 @@ struct shm_object *_shm_object_table_alloc_mem(struct shm_object_table *table,
 
        return obj;
 
+error_fcntl:
+       for (i = 0; i < 2; i++) {
+               ret = close(waitfd[i]);
+               if (ret) {
+                       PERROR("close");
+                       assert(0);
+               }
+       }
+error_pipe:
+       free(memory_map);
 alloc_error:
        return NULL;
 }
@@ -328,18 +359,31 @@ error_mmap:
  * Passing ownership of mem to object.
  */
 struct shm_object *shm_object_table_append_mem(struct shm_object_table *table,
-                       void *mem, size_t memory_map_size)
+                       void *mem, size_t memory_map_size, int wakeup_fd)
 {
        struct shm_object *obj;
+       int ret;
 
        if (table->allocated_len >= table->size)
                return NULL;
        obj = &table->objects[table->allocated_len];
 
-       obj->wait_fd[0] = -1;
-       obj->wait_fd[1] = -1;
+       obj->wait_fd[0] = -1;   /* read end is unset */
+       obj->wait_fd[1] = wakeup_fd;
        obj->shm_fd = -1;
 
+       ret = fcntl(obj->wait_fd[1], F_SETFD, FD_CLOEXEC);
+       if (ret < 0) {
+               PERROR("fcntl");
+               goto error_fcntl;
+       }
+       /* The write end of the pipe needs to be non-blocking */
+       ret = fcntl(obj->wait_fd[1], F_SETFL, O_NONBLOCK);
+       if (ret < 0) {
+               PERROR("fcntl");
+               goto error_fcntl;
+       }
+
        obj->type = SHM_OBJECT_MEM;
        obj->memory_map = mem;
        obj->memory_map_size = memory_map_size;
@@ -347,6 +391,9 @@ struct shm_object *shm_object_table_append_mem(struct shm_object_table *table,
        obj->index = table->allocated_len++;
 
        return obj;
+
+error_fcntl:
+       return NULL;
 }
 
 static
@@ -379,8 +426,21 @@ void shmp_object_destroy(struct shm_object *obj)
                break;
        }
        case SHM_OBJECT_MEM:
+       {
+               int ret, i;
+
+               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);
+                       }
+               }
                free(obj->memory_map);
                break;
+       }
        default:
                assert(0);
        }