[CRIU] [PATCH 03/28] rst: helpers for shared memory allocation introduced

[Kinsbursky Stanislav]

From: Stanislav Kinsbursky <skinsbursky at openvz.org>

Memory pool is 1 MB for now.

Signed-off-by: Stanislav Kinsbursky <skinsbursky at openvz.org>
---
 cr-restore.c   |   55 ++++++++++++++++++++++++++++++++++++++++++++++++++++---
 files.c        |   12 ++++++------
 include/util.h |    3 +++
 3 files changed, 61 insertions(+), 9 deletions(-)
-------------- next part --------------
diff --git a/cr-restore.c b/cr-restore.c
index 6ede2b7..e95b0f6 100644
--- a/cr-restore.c
+++ b/cr-restore.c
@@ -374,12 +374,61 @@ static inline void pstree_skip(int fd, struct pstree_entry *e)
 	lseek(fd, e->nr_children * sizeof(u32) + e->nr_threads * sizeof(u32), SEEK_CUR);
 }
 
+char *shm_pool_start, *shm_pool_end, *shm_pool_cur, *shm_pool_prev;
+
+void *xrealloc_shm(void *addr, int bytes)
+{
+	int curr_size;
+	int new_size = round_up(bytes, sizeof(long));
+
+	if (addr != shm_pool_prev)
+		return NULL;
+	curr_size = shm_pool_cur - shm_pool_prev;
+	if (new_size < curr_size)
+		shm_pool_cur = shm_pool_prev + new_size;
+	else {
+		int delta = new_size - curr_size;
+
+		if (shm_pool_cur + delta > shm_pool_end)
+			return NULL;
+		shm_pool_cur += delta;
+	}
+	return shm_pool_prev;
+}
+
+void *xmalloc_shm(int bytes)
+{
+	int size = round_up(bytes, sizeof(long));
+
+	if (shm_pool_cur + size > shm_pool_end)
+		return NULL;
+	shm_pool_prev = shm_pool_cur;
+	shm_pool_cur += size;
+	return shm_pool_prev;
+}
+
+static int init_shm_pool(int size)
+{
+	shm_pool_start = mmap(NULL, size, PROT_READ | PROT_WRITE,
+			      MAP_SHARED | MAP_ANON, 0, 0);
+	if (shm_pool_start == MAP_FAILED) {
+		pr_perror("Can't init shared memory pool");
+		return -1;
+	}
+	shm_pool_cur = shm_pool_prev = shm_pool_start;
+	shm_pool_end = shm_pool_start + size;
+	return 0;
+}
+
 static int prepare_shared(int ps_fd)
 {
 	int ret = 0;
 
 	pr_info("Preparing info about shared resources\n");
 
+	if (init_shm_pool(1 << 20))
+		return -1;
+
 	task_pids = xmalloc(PAGE_SIZE);
 	if (task_pids == NULL)
 		return -1;
@@ -401,9 +450,9 @@ static int prepare_shared(int ps_fd)
 	task_entries->nr = 0;
 	task_entries->start = CR_STATE_RESTORE;
 
-	pipes = mmap(NULL, 4096, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANON, 0, 0);
-	if (pipes == MAP_FAILED) {
-		pr_perror("Can't map pipes");
+	pipes = xmalloc_shm(4096);
+	if (pipes == NULL) {
+		pr_perror("Can't alloc pipes");
 		return -1;
 	}
 
diff --git a/files.c b/files.c
index e4a85e3..e9b7496 100644
--- a/files.c
+++ b/files.c
@@ -30,15 +30,15 @@ static struct fmap_fd *fmap_fds;
 
 int prepare_shared_fdinfo(void)
 {
-	fdinfo_descs = mmap(NULL, 4096, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANON, 0, 0);
-	if (fdinfo_descs == MAP_FAILED) {
-		pr_perror("Can't map fdinfo_descs");
+	fdinfo_descs = xmalloc_shm(4096);
+	if (fdinfo_descs == NULL) {
+		pr_perror("Can't alloc fdinfo_descs");
 		return -1;
 	}
 
-	fdinfo_list = mmap(NULL, 4096, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANON, 0, 0);
-	if (fdinfo_list == MAP_FAILED) {
-		pr_perror("Can't map fdinfo_list");
+	fdinfo_list = xmalloc_shm(4096);
+	if (fdinfo_list == NULL) {
+		pr_perror("Can't alloc fdinfo_list");
 		return -1;
 	}
 	return 0;
diff --git a/include/util.h b/include/util.h
index 9899cca..f9c2403 100644
--- a/include/util.h
+++ b/include/util.h
@@ -242,6 +242,9 @@ int do_open_proc(pid_t pid, int flags, const char *fmt, ...);
 #define xzalloc(size)		__xalloc(calloc, size, 1, size)
 #define xrealloc(p, size)	__xalloc(realloc, size, p, size)
 
+extern void *xmalloc_shm(int size);
+extern void *xrealloc_shm(void *addr, int new_size);
+
 #define xfree(p)		if (p) free(p)
 
 #define xrealloc_safe(pptr, size)					\