[Xen-changelog] [xen master] kexec: fix kexec_lock use in kexec_swap_images()

[patchbot@xxxxxxx]

commit 029c84d2efbebc02a4e9a6ee9a3a94289ca36f72
Author:     David Vrabel <david.vrabel@xxxxxxxxxx>
AuthorDate: Fri Nov 15 10:59:41 2013 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri Nov 15 10:59:41 2013 +0100

    kexec: fix kexec_lock use in kexec_swap_images()
    
    CID 1128573
    
    If a bad image type is supplied in a KEXECOP_unload hypercall, the
    kexec_lock in kexec_swap_images() was left locked, causing a deadlock
    on a subsequent image load or unload.
    
    The kexec_lock is only required to serialize the swap operation
    itself.
    
    Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
 xen/common/kexec.c |    7 ++-----
 1 files changed, 2 insertions(+), 5 deletions(-)

diff --git a/xen/common/kexec.c b/xen/common/kexec.c
index 9999bab..17f3ed7 100644
--- a/xen/common/kexec.c
+++ b/xen/common/kexec.c
@@ -785,17 +785,14 @@ static int kexec_swap_images(int type, struct kexec_image 
*new,
 
     *old = NULL;
 
-    spin_lock(&kexec_lock);
-
     if ( test_bit(KEXEC_FLAG_IN_PROGRESS, &kexec_flags) )
-    {
-        spin_unlock(&kexec_lock);
         return -EBUSY;
-    }
 
     if ( kexec_load_get_bits(type, &base, &bit) )
         return -EINVAL;
 
+    spin_lock(&kexec_lock);
+
     pos = (test_bit(bit, &kexec_flags) != 0);
     old_slot = base + pos;
     new_slot = base + !pos;
--
generated by git-patchbot for /home/xen/git/xen.git#master

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