This pull request contains the following changes for UML:

- Use fdatasync() in ubd
 - Add a generic "fd" vector transport
 - Minor cleanups and fixes
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Merge tag 'for-linus-5.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml

Pull UML updates from Richard Weinberger:

 - Use fdatasync() in ubd

 - Add a generic "fd" vector transport

 - Minor cleanups and fixes

* tag 'for-linus-5.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml:
  um: virtio: Replace zero-length array with flexible-array
  um: Use fdatasync() when mapping the UBD FSYNC command
  um: Do not evaluate compiler's library path when cleaning
  um: Neaten vu_err macro definition
  um: Add a generic "fd" vector transport
  um: Add include: memset() and memcpy() are in <string.h>

arch/um/drivers/vector_kern.h

@@ -129,7 +129,7 @@ struct vector_private {
 	struct vector_estats estats;
 	struct sock_fprog *bpf;
 
-	char user[0];
+	char user[];
 };
 
 extern int build_transport_data(struct vector_private *vp);

arch/um/drivers/vector_user.c

@@ -29,6 +29,7 @@
 #include <netdb.h>
 #include <stdlib.h>
 #include <os.h>
+#include <limits.h>
 #include <um_malloc.h>
 #include "vector_user.h"
 
@@ -42,6 +43,9 @@
 #define TRANS_RAW "raw"
 #define TRANS_RAW_LEN strlen(TRANS_RAW)
 
+#define TRANS_FD "fd"
+#define TRANS_FD_LEN strlen(TRANS_FD)
+
 #define VNET_HDR_FAIL "could not enable vnet headers on fd %d"
 #define TUN_GET_F_FAIL "tapraw: TUNGETFEATURES failed: %s"
 #define L2TPV3_BIND_FAIL "l2tpv3_open : could not bind socket err=%i"
@@ -347,6 +351,59 @@ unix_cleanup:
 	return NULL;
 }
 
+static int strtofd(const char *nptr)
+{
+	long fd;
+	char *endptr;
+
+	if (nptr == NULL)
+		return -1;
+
+	errno = 0;
+	fd = strtol(nptr, &endptr, 10);
+	if (nptr == endptr ||
+		errno != 0 ||
+		*endptr != '\0' ||
+		fd < 0 ||
+		fd > INT_MAX) {
+		return -1;
+	}
+	return fd;
+}
+
+static struct vector_fds *user_init_fd_fds(struct arglist *ifspec)
+{
+	int fd = -1;
+	char *fdarg = NULL;
+	struct vector_fds *result = NULL;
+
+	fdarg = uml_vector_fetch_arg(ifspec, "fd");
+	fd = strtofd(fdarg);
+	if (fd == -1) {
+		printk(UM_KERN_ERR "fd open: bad or missing fd argument");
+		goto fd_cleanup;
+	}
+
+	result = uml_kmalloc(sizeof(struct vector_fds), UM_GFP_KERNEL);
+	if (result == NULL) {
+		printk(UM_KERN_ERR "fd open: allocation failed");
+		goto fd_cleanup;
+	}
+
+	result->rx_fd = fd;
+	result->tx_fd = fd;
+	result->remote_addr_size = 0;
+	result->remote_addr = NULL;
+	return result;
+
+fd_cleanup:
+	if (fd >= 0)
+		os_close_file(fd);
+	if (result != NULL)
+		kfree(result);
+	return NULL;
+}
+
 static struct vector_fds *user_init_raw_fds(struct arglist *ifspec)
 {
 	int rxfd = -1, txfd = -1;
@@ -578,6 +635,8 @@ struct vector_fds *uml_vector_user_open(
 		return user_init_socket_fds(parsed, ID_L2TPV3);
 	if (strncmp(transport, TRANS_BESS, TRANS_BESS_LEN) == 0)
 		return user_init_unix_fds(parsed, ID_BESS);
+	if (strncmp(transport, TRANS_FD, TRANS_FD_LEN) == 0)
+		return user_init_fd_fds(parsed);
 	return NULL;
 }
 

arch/um/drivers/vhost_user.h

@@ -78,7 +78,7 @@ struct vhost_user_config {
 	u32 offset;
 	u32 size;
 	u32 flags;
-	u8 payload[0]; /* Variable length */
+	u8 payload[]; /* Variable length */
 } __packed;
 
 struct vhost_user_vring_state {

arch/um/drivers/virtio_uml.c

@@ -74,7 +74,7 @@ struct virtio_uml_vq_info {
 
 extern unsigned long long physmem_size, highmem;
 
-#define vu_err(vu_dev, ...)	dev_err(&(vu_dev)->pdev->dev, __VA_ARGS__)
+#define vu_err(vu_dev, ...)	dev_err(&(vu_dev)->pdev->dev, ##__VA_ARGS__)
 
 /* Vhost-user protocol */
 

arch/um/os-Linux/file.c

@@ -6,6 +6,7 @@
 #include <stdio.h>
 #include <unistd.h>
 #include <stdlib.h>
+#include <string.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <signal.h>
@@ -289,7 +290,7 @@ int os_write_file(int fd, const void *buf, int len)
 
 int os_sync_file(int fd)
 {
-	int n = fsync(fd);
+	int n = fdatasync(fd);
 
 	if (n < 0)
 		return -errno;