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[v4,22/33] vfio/migration: Convert bytes_transferred counter to atomic

Message ID 41ce794acd0714c69e212ff43ddea09cd9a47eec.1738171076.git.maciej.szmigiero@oracle.com (mailing list archive)
State New
Headers show
Series Multifd ���� device state transfer support with VFIO consumer | expand

Commit Message

Maciej S. Szmigiero Jan. 30, 2025, 10:08 a.m. UTC 
From: "Maciej S. Szmigiero" <maciej.szmigiero@oracle.com>

So it can be safety accessed from multiple threads.

Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
---
 hw/vfio/migration.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

Comments

Cédric Le Goater Jan. 30, 2025, 9:35 p.m. UTC | #1 
On 1/30/25 11:08, Maciej S. Szmigiero wrote:
> From: "Maciej S. Szmigiero" <maciej.szmigiero@oracle.com>
> 
> So it can be safety accessed from multiple threads.
> 
> Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
> ---
>   hw/vfio/migration.c | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
> index f5df5ef17080..cbb1e0b6f852 100644
> --- a/hw/vfio/migration.c
> +++ b/hw/vfio/migration.c
> @@ -416,7 +416,7 @@ static ssize_t vfio_save_block(QEMUFile *f, VFIOMigration *migration)
>       qemu_put_be64(f, VFIO_MIG_FLAG_DEV_DATA_STATE);
>       qemu_put_be64(f, data_size);
>       qemu_put_buffer(f, migration->data_buffer, data_size);
> -    bytes_transferred += data_size;
> +    qatomic_add(&bytes_transferred, data_size);

bytes_transferred should of type : aligned_uint64_t

>   
>       trace_vfio_save_block(migration->vbasedev->name, data_size);
>   
> @@ -1038,12 +1038,12 @@ static int vfio_block_migration(VFIODevice *vbasedev, Error *err, Error **errp)
>   
>   int64_t vfio_mig_bytes_transferred(void)
>   {
> -    return bytes_transferred;
> +    return qatomic_read(&bytes_transferred);

please use qatomic_read_u64()

>   }
>   
>   void vfio_reset_bytes_transferred(void)
>   {
> -    bytes_transferred = 0;
> +    qatomic_set(&bytes_transferred, 0);

and qatomic_set_u64().

No need to resend for that (yet) but it might explain the test issues.

Thanks,

C.


>   }
>   
>   /*
>
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Patch

diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
index f5df5ef17080..cbb1e0b6f852 100644
--- a/hw/vfio/migration.c
+++ b/hw/vfio/migration.c
@@ -416,7 +416,7 @@  static ssize_t vfio_save_block(QEMUFile *f, VFIOMigration *migration)
     qemu_put_be64(f, VFIO_MIG_FLAG_DEV_DATA_STATE);
     qemu_put_be64(f, data_size);
     qemu_put_buffer(f, migration->data_buffer, data_size);
-    bytes_transferred += data_size;
+    qatomic_add(&bytes_transferred, data_size);
 
     trace_vfio_save_block(migration->vbasedev->name, data_size);
 
@@ -1038,12 +1038,12 @@  static int vfio_block_migration(VFIODevice *vbasedev, Error *err, Error **errp)
 
 int64_t vfio_mig_bytes_transferred(void)
 {
-    return bytes_transferred;
+    return qatomic_read(&bytes_transferred);
 }
 
 void vfio_reset_bytes_transferred(void)
 {
-    bytes_transferred = 0;
+    qatomic_set(&bytes_transferred, 0);
 }
 
 /*