[Qemu-devel] [PATCH resend 1/3] savevm: add comments for qemu_file_get_error()

[Qemu-devel] [PATCH resend 1/3] savevm: add comments for qemu_file_get_error()

[Lei Li]

Add comments for qemu_file_get_error(), as its return value
is not very clear.

Signed-off-by: Lei Li <lilei@linux.vnet.ibm.com>
---
 savevm.c |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/savevm.c b/savevm.c
index 03fc4d9..95a11f9 100644
--- a/savevm.c
+++ b/savevm.c
@@ -566,6 +566,13 @@ QEMUFile *qemu_fopen_ops(void *opaque, const QEMUFileOps *ops)
     return f;
 }
 
+/*
+ * Get last error for stream f
+ *
+ * Return negative error value if there has been an error on previous
+ * operations, return 0 if no error happened.
+ *
+ */
 int qemu_file_get_error(QEMUFile *f)
 {
     return f->last_error;
-- 
1.7.7.6

[Qemu-devel] [PATCH resend 2/3] savevm: fix wrong error set by ram_control_load_hook()

[Lei Li]

It should set negative error value if there has been an error.

Signed-off-by: Lei Li <lilei@linux.vnet.ibm.com>
---
 savevm.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/savevm.c b/savevm.c
index 95a11f9..a0be109 100644
--- a/savevm.c
+++ b/savevm.c
@@ -649,7 +649,7 @@ void ram_control_after_iterate(QEMUFile *f, uint64_t flags)
 
 void ram_control_load_hook(QEMUFile *f, uint64_t flags)
 {
-    int ret = 0;
+    int ret = -EINVAL;
 
     if (f->ops->hook_ram_load) {
         ret = f->ops->hook_ram_load(f, f->opaque, flags);
-- 
1.7.7.6

[Qemu-devel] [PATCH resend 3/3] arch_init: right return for ram_save_iterate

[Lei Li]

Signed-off-by: Lei Li <lilei@linux.vnet.ibm.com>
---
 arch_init.c |    7 +------
 1 files changed, 1 insertions(+), 6 deletions(-)

diff --git a/arch_init.c b/arch_init.c
index 94d45e1..a34437c 100644
--- a/arch_init.c
+++ b/arch_init.c
@@ -709,16 +709,11 @@ static int ram_save_iterate(QEMUFile *f, void *opaque)
      */
     ram_control_after_iterate(f, RAM_CONTROL_ROUND);
 
-    if (ret < 0) {
-        bytes_transferred += total_sent;
-        return ret;
-    }
-
     qemu_put_be64(f, RAM_SAVE_FLAG_EOS);
     total_sent += 8;
     bytes_transferred += total_sent;
 
-    return total_sent;
+    return qemu_file_get_error(f);
 }
 
 static int ram_save_complete(QEMUFile *f, void *opaque)
-- 
1.7.7.6

Re: [Qemu-devel] [PATCH resend 2/3] savevm: fix wrong error set by ram_control_load_hook()

[Michael R. Hines]

On 08/23/2013 09:30 AM, Lei Li wrote:
> It should set negative error value if there has been an error.
>
> Signed-off-by: Lei Li <lilei@linux.vnet.ibm.com>
> ---
>   savevm.c |    2 +-
>   1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/savevm.c b/savevm.c
> index 95a11f9..a0be109 100644
> --- a/savevm.c
> +++ b/savevm.c
> @@ -649,7 +649,7 @@ void ram_control_after_iterate(QEMUFile *f, uint64_t flags)
>
>   void ram_control_load_hook(QEMUFile *f, uint64_t flags)
>   {
> -    int ret = 0;
> +    int ret = -EINVAL;
>
>       if (f->ops->hook_ram_load) {
>           ret = f->ops->hook_ram_load(f, f->opaque, flags);

Re: [Qemu-devel] [PATCH resend 2/3] savevm: fix wrong error set by ram_control_load_hook()

[Michael R. Hines]

On 08/23/2013 09:30 AM, Lei Li wrote:
> It should set negative error value if there has been an error.
>
> Signed-off-by: Lei Li <lilei@linux.vnet.ibm.com>
> ---
>   savevm.c |    2 +-
>   1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/savevm.c b/savevm.c
> index 95a11f9..a0be109 100644
> --- a/savevm.c
> +++ b/savevm.c
> @@ -649,7 +649,7 @@ void ram_control_after_iterate(QEMUFile *f, uint64_t flags)
>
>   void ram_control_load_hook(QEMUFile *f, uint64_t flags)
>   {
> -    int ret = 0;
> +    int ret = -EINVAL;
>
>       if (f->ops->hook_ram_load) {
>           ret = f->ops->hook_ram_load(f, f->opaque, flags);

Reviewed-By: Michael R. Hines <mrhines@us.ibm.com>

Re: [Qemu-devel] [PATCH resend 3/3] arch_init: right return for ram_save_iterate

[Paolo Bonzini]

Il 23/08/2013 15:30, Lei Li ha scritto:
> -    if (ret < 0) {
> -        bytes_transferred += total_sent;
> -        return ret;
> -    }
> -
>      qemu_put_be64(f, RAM_SAVE_FLAG_EOS);
>      total_sent += 8;
>      bytes_transferred += total_sent;
>  
> -    return total_sent;
> +    return qemu_file_get_error(f);

No, this will never make ram_save_iterate (and thus
qemu_savevm_state_iterate) return a positive, non-zero value.  Thus:

    ret = qemu_file_get_error(f);
    if (ret < 0) {
        return ret;
    }
    return total_sent;

If you look at the code, you can see that it never returns zero.
Probably it should do something like

    bytes_transferred += total_sent;

    /* Do not count these 8 bytes into total_sent, so that we can
     * return 0 if no page had been dirtied.
     */
    qemu_put_be64(f, RAM_SAVE_FLAG_EOS);
    bytes_transferred += 8;

and then proceed as above with "ret = qemu_file_get_error(f)".

Paolo

Re: [Qemu-devel] [PATCH resend 3/3] arch_init: right return for ram_save_iterate

[Lei Li]

On 08/26/2013 04:27 PM, Paolo Bonzini wrote:
> Il 23/08/2013 15:30, Lei Li ha scritto:
>> -    if (ret < 0) {
>> -        bytes_transferred += total_sent;
>> -        return ret;
>> -    }
>> -
>>       qemu_put_be64(f, RAM_SAVE_FLAG_EOS);
>>       total_sent += 8;
>>       bytes_transferred += total_sent;
>>   
>> -    return total_sent;
>> +    return qemu_file_get_error(f);
> No, this will never make ram_save_iterate (and thus
> qemu_savevm_state_iterate) return a positive, non-zero value.  Thus:
>
>      ret = qemu_file_get_error(f);
>      if (ret < 0) {
>          return ret;
>      }
>      return total_sent;
>
> If you look at the code, you can see that it never returns zero.
> Probably it should do something like
>
>      bytes_transferred += total_sent;
>
>      /* Do not count these 8 bytes into total_sent, so that we can
>       * return 0 if no page had been dirtied.
>       */
>      qemu_put_be64(f, RAM_SAVE_FLAG_EOS);
>      bytes_transferred += 8;
>
> and then proceed as above with "ret = qemu_file_get_error(f)".

Yes, you are right.

>
> Paolo
>


-- 
Lei