From: Vitaly Kuznetsov <vkuznets@redhat.com>
Date: Fri, 26 Sep 2014 15:20:01 +0000 (+0200)
Subject: x86/hvm: remove stray lock release from hvm_ioreq_server_init()
X-Git-Tag: 4.5.0-rc1~149
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=a608c40d4ffc489a26e3677d060084ec3d29d88f;p=xen.git

x86/hvm: remove stray lock release from hvm_ioreq_server_init()

If HVM_PARAM_IOREQ_PFN, HVM_PARAM_BUFIOREQ_PFN, or HVM_PARAM_BUFIOREQ_EVTCHN
parameters are read when guest domain is dying it leads to the following
ASSERT:

(XEN) Assertion '_raw_spin_is_locked(lock)' failed at ...workspace/KERNEL/xen/xen/include/asm/spinlock.h:18
(XEN) ----[ Xen-4.5-unstable  x86_64  debug=y  Not tainted ]----
...
(XEN) Xen call trace:
(XEN)    [<ffff82d08012b07f>] _spin_unlock+0x27/0x30
(XEN)    [<ffff82d0801b6103>] hvm_create_ioreq_server+0x3df/0x49a
(XEN)    [<ffff82d0801bcceb>] do_hvm_op+0x12bf/0x27a0
(XEN)    [<ffff82d08022b9bb>] syscall_enter+0xeb/0x145

The root cause of this issue is the fact that ioreq_server.lock is being
released twice - first in hvm_ioreq_server_init() and then in hvm_create_ioreq_server().
Drop the lock release from hvm_ioreq_server_init() as we don't take it here, do minor
label cleanup.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
---

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 299a256b45..7e2d5d106e 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -918,30 +918,28 @@ static int hvm_ioreq_server_init(struct hvm_ioreq_server *s, struct domain *d,
 
     rc = hvm_ioreq_server_alloc_rangesets(s, is_default);
     if ( rc )
-        goto fail1;
+        return rc;
 
     rc = hvm_ioreq_server_map_pages(s, is_default, handle_bufioreq);
     if ( rc )
-        goto fail2;
+        goto fail_map;
 
     for_each_vcpu ( d, v )
     {
         rc = hvm_ioreq_server_add_vcpu(s, is_default, v);
         if ( rc )
-            goto fail3;
+            goto fail_add;
     }
 
     return 0;
 
- fail3:
+ fail_add:
     hvm_ioreq_server_remove_all_vcpus(s);
     hvm_ioreq_server_unmap_pages(s, is_default);
 
- fail2:
+ fail_map:
     hvm_ioreq_server_free_rangesets(s, is_default);
 
- fail1:
-    spin_unlock(&d->arch.hvm_domain.ioreq_server.lock);
     return rc;
 }