[09/16] block/qed: Fix missing ERRP_GUARD() for error_prepend()

Commit Message

Zhao Liu Feb. 28, 2024, 4:37 p.m. UTC

From: Zhao Liu <[e-mail]>

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 bdrv_qed_co_invalidate_cache() passes @errp to error_prepend()
without ERRP_GUARD().

Though it is a BlockDriver.bdrv_co_invalidate_cache() method, and
currently its @errp parameter only points to callers' local_err, to
follow the requirement of @errp, add missing ERRP_GUARD() at the
beginning of this function.

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

Cc: Stefan Hajnoczi <[e-mail]>
Cc: Kevin Wolf <[e-mail]>
Cc: Hanna Reitz <[e-mail]>
Signed-off-by: Zhao Liu <[e-mail]>
---
 block/qed.c | 1 +
 1 file changed, 1 insertion(+)

Comments

Stefan Hajnoczi Feb. 28, 2024, 6:42 p.m. UTC | #1

On Thu, Feb 29, 2024 at 12:37:16AM +0800, Zhao Liu wrote:
> From: Zhao Liu <[e-mail]>
> 
> 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 bdrv_qed_co_invalidate_cache() passes @errp to error_prepend()
> without ERRP_GUARD().
> 
> Though it is a BlockDriver.bdrv_co_invalidate_cache() method, and
> currently its @errp parameter only points to callers' local_err, to
> follow the requirement of @errp, add missing ERRP_GUARD() at the
> beginning of this function.
> 
> [1]: Issue description in the commit message of commit ae7c80a7bd73
>      ("error: New macro ERRP_GUARD()").
> 
> Cc: Stefan Hajnoczi <[e-mail]>
> Cc: Kevin Wolf <[e-mail]>
> Cc: Hanna Reitz <[e-mail]>
> Signed-off-by: Zhao Liu <[e-mail]>
> ---
>  block/qed.c | 1 +
>  1 file changed, 1 insertion(+)

Reviewed-by: Stefan Hajnoczi <[e-mail]>

Patch

diff --git a/block/qed.c b/block/qed.c
index bc2f0a61c0a9..fa5bc1108552 100644
--- a/block/qed.c
+++ b/block/qed.c
@@ -1579,6 +1579,7 @@  bdrv_qed_co_change_backing_file(BlockDriverState *bs, const char *backing_file,
 static void coroutine_fn GRAPH_RDLOCK
 bdrv_qed_co_invalidate_cache(BlockDriverState *bs, Error **errp)
 {
+    ERRP_GUARD();
     BDRVQEDState *s = bs->opaque;
     int ret;