uml: network interface hotplug error handling

This fixes a number of problems associated with network interface hotplug.

The userspace initialization function can fail in some cases, but the
failure was never passed back to eth_configure, which proceeded with the
configuration.  This results in a zombie device that is present, but can't
work.  This is fixed by allowing the initialization routines to return an
error, which is checked, and the configuration aborted on failure.

eth_configure failed to check for many failures.  Even when it did check,
it didn't undo whatever initializations has already happened, so a present,
but partially initialized and non-working device could result.  It now
checks everything that can fail, and bails out, undoing whatever had been
done.

The return value of eth_configure was always ignored, so it is now just
void.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Jeff Garzik <jeff@garzik.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 2 deletions

diff --git a/arch/um/drivers/pcap_user.c b/arch/um/drivers/pcap_user.c
index a1747dc0ff6f..dc0a903ef9a6 100644
--- a/arch/um/drivers/pcap_user.c
+++ b/arch/um/drivers/pcap_user.c
@@ -18,7 +18,7 @@
 
 #define PCAP_FD(p) (*(int *)(p))
 
-static void pcap_user_init(void *data, void *dev)
+static int pcap_user_init(void *data, void *dev)
 {
         struct pcap_data *pri = data;
         pcap_t *p;
@@ -28,11 +28,12 @@ static void pcap_user_init(void *data, void *dev)
         if(p == NULL){
                 printk("pcap_user_init : pcap_open_live failed - '%s'\n", 
                        errors);
-                return;
+                return -EINVAL;
         }
 
         pri->dev = dev;
         pri->pcap = p;
+        return 0;
 }
 
 static int pcap_open(void *data)