Re: [PATCH] kexec: don't disable interrupts when acquiring load/unload lock

[Andrew Cooper <andrew.cooper3@citrix.com>]

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On 06/11/13 12:22, Jan Beulich wrote:
> This doesn't appear to have served any purpose other than causing
> map_pages_to_xen() to be (incorrectly) invoked with interrupts
> disabled. In particular, serialization against actual kexec-ing is done
> without this lock being involved. Clarify the scope of the lock at once
> by making it local to do_kexec_op_internal().
>
> Once at it, also drop a pointless initializer.
>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>

Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>

>
> --- a/xen/common/kexec.c
> +++ b/xen/common/kexec.c
> @@ -55,8 +55,6 @@ static xen_kexec_image_t kexec_image[KEX
>  
>  static unsigned long kexec_flags = 0; /* the lowest bits are for KEXEC_IMAGE... */
>  
> -static spinlock_t kexec_lock = SPIN_LOCK_UNLOCKED;
> -
>  static unsigned char vmcoreinfo_data[VMCOREINFO_BYTES];
>  static size_t vmcoreinfo_size = 0;
>  
> @@ -851,10 +849,9 @@ static int do_kexec_op_internal(unsigned
>                                  XEN_GUEST_HANDLE_PARAM(void) uarg,
>                                  bool_t compat)
>  {
> -    unsigned long flags;
> -    int ret = -EINVAL;
> +    static DEFINE_SPINLOCK(kexec_lock);
> +    int ret = xsm_kexec(XSM_PRIV);
>  
> -    ret = xsm_kexec(XSM_PRIV);
>      if ( ret )
>          return ret;
>  
> @@ -868,7 +865,7 @@ static int do_kexec_op_internal(unsigned
>          break;
>      case KEXEC_CMD_kexec_load:
>      case KEXEC_CMD_kexec_unload:
> -        spin_lock_irqsave(&kexec_lock, flags);
> +        spin_lock(&kexec_lock);
>          if (!test_bit(KEXEC_FLAG_IN_PROGRESS, &kexec_flags))
>          {
>                  if (compat)
> @@ -876,7 +873,7 @@ static int do_kexec_op_internal(unsigned
>                  else
>                          ret = kexec_load_unload(op, uarg);
>          }
> -        spin_unlock_irqrestore(&kexec_lock, flags);
> +        spin_unlock(&kexec_lock);
>          break;
>      case KEXEC_CMD_kexec:
>          ret = kexec_exec(uarg);
>
>
>
>
>
> _______________________________________________
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> Xen-devel@lists.xen.org
> http://lists.xen.org/xen-devel


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