[uml-devel] VDE backend does not handle EINTR properly

[Frank Laub <frank.laub@gmail.com>]

When running the VDE backend with 2 uml instances and running iperf 
between them, the vde_send() function often returns EINTR. I noticed 
that this is accounted for in net_user.c via the use of the 
CATCH_EINTR() macro. Thus the following patch uses the same approach for 
calls into VDE. It could be argued that the VDE library itself should 
handle EINTR, but this patch will work with older (or current) versions 
of VDE. This patch was created against 3.0.3.

--- a/arch/um/drivers/vde_user.c
+++ b/arch/um/drivers/vde_user.c
@@ -11,6 +11,7 @@
  #include "um_malloc.h"
  #include "user.h"
  #include "vde.h"
+#include "os.h"

  static int vde_user_init(void *data, void *dev)
  {
@@ -103,7 +104,7 @@ int vde_user_read(void *conn, void *buf,
      if (vconn == NULL)
          return 0;

-    rv = vde_recv(vconn, buf, len, 0);
+    CATCH_EINTR(rv = vde_recv(vconn, buf, len, 0));
      if (rv < 0) {
          if (errno == EAGAIN)
              return 0;
@@ -118,10 +119,19 @@ int vde_user_read(void *conn, void *buf,
  int vde_user_write(void *conn, void *buf, int len)
  {
      VDECONN *vconn = conn;
+    int rv;

      if (vconn == NULL)
          return 0;

-    return vde_send(vconn, buf, len, 0);
+    CATCH_EINTR(rv = vde_send(vconn, buf, len, 0));
+    if (rv < 0) {
+        if (errno == EAGAIN)
+            return 0;
+        return -errno;
+    }
+    else if (rv == 0)
+        return -ENOTCONN;
+    return rv;
  }



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