lguest: Read length of device_cap later

Read the length of the capability with type VIRTIO_PCI_CAP_DEVICE_CFG
only when we're sure we're going to need it. Which is just before the
check whether the virtio console actually has an emerg_wr field.

Signed-off-by: Paul Bolle <pebolle@tiscali.nl>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: lguest@lists.ozlabs.org
Link: http://lkml.kernel.org/r/1457006501-5377-2-git-send-email-pebolle@tiscali.nl
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 3 insertions, 4 deletions

diff --git a/arch/x86/lguest/boot.c b/arch/x86/lguest/boot.c
index 3847e736702e..146d11c8cf78 100644
--- a/arch/x86/lguest/boot.c
+++ b/arch/x86/lguest/boot.c
@@ -1258,7 +1258,7 @@ static void probe_pci_console(void)
                 u8 vndr = read_pci_config_byte(0, 1, 0, cap);
                 if (vndr == PCI_CAP_ID_VNDR) {
                         u8 type, bar;
-                        u32 offset, length;
+                        u32 offset;
 
                         type = read_pci_config_byte(0, 1, 0,
                             cap + offsetof(struct virtio_pci_cap, cfg_type));
@@ -1266,15 +1266,12 @@ static void probe_pci_console(void)
                             cap + offsetof(struct virtio_pci_cap, bar));
                         offset = read_pci_config(0, 1, 0,
                             cap + offsetof(struct virtio_pci_cap, offset));
-                        length = read_pci_config(0, 1, 0,
-                            cap + offsetof(struct virtio_pci_cap, length));
 
                         switch (type) {
                         case VIRTIO_PCI_CAP_DEVICE_CFG:
                                 if (bar == 0) {
                                         device_cap = cap;
                                         device_offset = offset;
-                                        device_len = length;
                                 }
                                 break;
                         case VIRTIO_PCI_CAP_PCI_CFG:
@@ -1297,6 +1294,8 @@ static void probe_pci_console(void)
          * emerg_wr.  If it doesn't support VIRTIO_CONSOLE_F_EMERG_WRITE
          * it should ignore the access.
          */
+        device_len = read_pci_config(0, 1, 0,
+                        device_cap + offsetof(struct virtio_pci_cap, length));
         if (device_len < (offsetof(struct virtio_console_config, emerg_wr)
                           + sizeof(u32))) {
                 printk(KERN_ERR "lguest: console missing emerg_wr field\n");