[v1] Cleanup up to fix missing ERRP_GUARD() for error_prepend()

[PATCH 07/16] block/qcow2-bitmap: Fix missing ERRP_GUARD() for error_prepend()

Zhao Liu posted 16 patches 9 months ago

Diff against v1 v2
Download mbox

Maintainers: Yi Liu <yi.l.liu@intel.com>, Eric Auger <eric.auger@redhat.com>, Zhenzhong Duan <zhenzhong.duan@intel.com>, Kevin Wolf <kwolf@redhat.com>, Hanna Reitz <hreitz@redhat.com>, John Snow <jsnow@redhat.com>, Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>, Eric Blake <eblake@redhat.com>, Stefan Hajnoczi <stefanha@redhat.com>, Fam Zheng <fam@euphon.net>, "Philippe Mathieu-Daudé" <philmd@linaro.org>, Stefan Weil <sw@weilnetz.de>, "Michael S. Tsirkin" <mst@redhat.com>, Stefano Stabellini <sstabellini@kernel.org>, Anthony Perard <anthony.perard@citrix.com>, Paul Durrant <paul@xen.org>, "Marc-André Lureau" <marcandre.lureau@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>, Paul Burton <paulburton@kernel.org>, Aleksandar Rikalo <aleksandar.rikalo@syrmia.com>, "Daniel P. Berrangé" <berrange@redhat.com>, Eduardo Habkost <eduardo@habkost.net>, Markus Armbruster <armbru@redhat.com>, Michael Roth <michael.roth@amd.com>

There is a newer version of this series

Expand all Fold all

[PATCH 07/16] block/qcow2-bitmap: Fix missing ERRP_GUARD() for error_prepend()

Posted by Zhao Liu 9 months ago

From: Zhao Liu <zhao1.liu@intel.com>

As the comment in qapi/error, passing @errp to error_prepend() requires
ERRP_GUARD():

* = Why, when and how to use ERRP_GUARD() =
*
* Without ERRP_GUARD(), use of the @errp parameter is restricted:
...
* - It should not be passed to error_prepend(), error_vprepend() or
*   error_append_hint(), because that doesn't work with &error_fatal.
* ERRP_GUARD() lifts these restrictions.
*
* To use ERRP_GUARD(), add it right at the beginning of the function.
* @errp can then be used without worrying about the argument being
* NULL or &error_fatal.

ERRP_GUARD() could avoid the case when @errp is the pointer of
error_fatal, the user can't see this additional information, because
exit() happens in error_setg earlier than information is added [1].

The qcow2_co_can_store_new_dirty_bitmap() passes @errp to
error_prepend(). As a BlockDriver.bdrv_co_can_store_new_dirty_bitmap
method, it's called by bdrv_co_can_store_new_dirty_bitmap().

Its caller is not being called anywhere, but as the API in
include/block/block-io.h, we can't ensure what kind of @errp future
users will pass in.

To avoid potential issues as [1] said, add missing ERRP_GUARD() at the
beginning of qcow2_co_can_store_new_dirty_bitmap().

[1]: Issue description in the commit message of commit ae7c80a7bd73
     ("error: New macro ERRP_GUARD()").

Cc: Eric Blake <eblake@redhat.com>
Cc: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Cc: John Snow <jsnow@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>
Cc: Hanna Reitz <hreitz@redhat.com>
Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
---
 block/qcow2-bitmap.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/block/qcow2-bitmap.c b/block/qcow2-bitmap.c
index 0e567ed588d7..874ea5694851 100644
--- a/block/qcow2-bitmap.c
+++ b/block/qcow2-bitmap.c
@@ -1710,6 +1710,7 @@ bool coroutine_fn qcow2_co_can_store_new_dirty_bitmap(BlockDriverState *bs,
                                                       uint32_t granularity,
                                                       Error **errp)
 {
+    ERRP_GUARD();
     BDRVQcow2State *s = bs->opaque;
     BdrvDirtyBitmap *bitmap;
     uint64_t bitmap_directory_size = 0;
-- 
2.34.1

Re: [PATCH 07/16] block/qcow2-bitmap: Fix missing ERRP_GUARD() for error_prepend()

Posted by Vladimir Sementsov-Ogievskiy 9 months ago

On 28.02.24 19:37, Zhao Liu wrote:
> From: Zhao Liu<zhao1.liu@intel.com>
> 
> As the comment in qapi/error, passing @errp to error_prepend() requires
> ERRP_GUARD():
> 
> * = Why, when and how to use ERRP_GUARD() =
> *
> * Without ERRP_GUARD(), use of the @errp parameter is restricted:
> ...
> * - It should not be passed to error_prepend(), error_vprepend() or
> *   error_append_hint(), because that doesn't work with &error_fatal.
> * ERRP_GUARD() lifts these restrictions.
> *
> * To use ERRP_GUARD(), add it right at the beginning of the function.
> * @errp can then be used without worrying about the argument being
> * NULL or &error_fatal.
> 
> ERRP_GUARD() could avoid the case when @errp is the pointer of
> error_fatal, the user can't see this additional information, because
> exit() happens in error_setg earlier than information is added [1].
> 
> The qcow2_co_can_store_new_dirty_bitmap() passes @errp to
> error_prepend(). As a BlockDriver.bdrv_co_can_store_new_dirty_bitmap
> method, it's called by bdrv_co_can_store_new_dirty_bitmap().
> 
> Its caller is not being called anywhere, but as the API in
> include/block/block-io.h, we can't ensure what kind of @errp future
> users will pass in.
> 
> To avoid potential issues as [1] said, add missing ERRP_GUARD() at the
> beginning of qcow2_co_can_store_new_dirty_bitmap().
> 
> [1]: Issue description in the commit message of commit ae7c80a7bd73
>       ("error: New macro ERRP_GUARD()").
> 
> Cc: Eric Blake<eblake@redhat.com>
> Cc: Vladimir Sementsov-Ogievskiy<vsementsov@yandex-team.ru>
> Cc: John Snow<jsnow@redhat.com>
> Cc: Kevin Wolf<kwolf@redhat.com>
> Cc: Hanna Reitz<hreitz@redhat.com>
> Signed-off-by: Zhao Liu<zhao1.liu@intel.com>

Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>

-- 
Best regards,
Vladimir