[Qemu-devel] [PATCH 2/3] qmp: dump-guest-memory: don't spin if non-blocking fd would block

[Luiz Capitulino]

fd_write_vmcore() will indefinitely spin for a non-blocking
file-descriptor that would block. However, if the fd is non-blocking,
how does it make sense to spin?

Change this behavior to return an error instead.

Note that this can only happen with an fd provided by a management
application. The fd opened internally by dump-guest-memory is blocking.

Signed-off-by: Luiz Capitulino <address@hidden>
---
 dump.c | 13 +++----------
 1 file changed, 3 insertions(+), 10 deletions(-)

diff --git a/dump.c b/dump.c
index 2bf8d8d..5eea015 100644
--- a/dump.c
+++ b/dump.c
@@ -100,18 +100,11 @@ static void dump_error(DumpState *s, const char *reason)
 static int fd_write_vmcore(void *buf, size_t size, void *opaque)
 {
     DumpState *s = opaque;
-    int fd = s->fd;
     size_t writen_size;
 
-    /* The fd may be passed from user, and it can be non-blocked */
-    while (size) {
-        writen_size = qemu_write_full(fd, buf, size);
-        if (writen_size != size && errno != EAGAIN) {
-            return -1;
-        }
-
-        buf += writen_size;
-        size -= writen_size;
+    writen_size = qemu_write_full(s->fd, buf, size);
+    if (writen_size != size) {
+        return -1;
     }
 
     return 0;
-- 
1.7.12.315.g682ce8b