Re: [PATCH 43/52] migration/rdma: Convert qemu_rdma_alloc_pd_cq() to Error

[Zhijian Li (Fujitsu)]

On 18/09/2023 22:41, Markus Armbruster wrote:
> Functions that use an Error **errp parameter to return errors should
> not also report them to the user, because reporting is the caller's
> job.  When the caller does, the error is reported twice.  When it
> doesn't (because it recovered from the error), there is no error to
> report, i.e. the report is bogus.
> 
> qemu_rdma_source_init() violates this principle: it calls
> error_report() via qemu_rdma_alloc_pd_cq().  I elected not to
> investigate how callers handle the error, i.e. precise impact is not
> known.
> 
> Clean this up by converting qemu_rdma_alloc_pd_cq() to Error.
> 
> Signed-off-by: Markus Armbruster<armbru@redhat.com>
> ---
>   migration/rdma.c | 27 ++++++++++++++-------------
>   1 file changed, 14 insertions(+), 13 deletions(-)

[...]


> @@ -2451,6 +2451,7 @@ static void qemu_rdma_cleanup(RDMAContext *rdma)
>   
>   static int qemu_rdma_source_init(RDMAContext *rdma, bool pin_all, Error 
> **errp)
>   {
> +    ERRP_GUARD();
>       int ret, idx;
>   
>       /*
> @@ -2464,12 +2465,12 @@ static int qemu_rdma_source_init(RDMAContext *rdma, 
> bool pin_all, Error **errp)
>           goto err_rdma_source_init;
>       }
>   
> -    ret = qemu_rdma_alloc_pd_cq(rdma);
> +    ret = qemu_rdma_alloc_pd_cq(rdma, errp);
>       if (ret < 0) {
> -        error_setg(errp, "RDMA ERROR: "
> -                   "rdma migration: error allocating pd and cq! Your mlock()"
> -                   " limits may be too low. Please check $ ulimit -a # and "
> -                   "search for 'ulimit -l' in the output");
> +        error_append_hint(errp,
> +                          "Your mlock() limits may be too low. "
> +                          "Please check $ ulimit -a # and "
> +                          "search for 'ulimit -l' in the output\n");


I think we could freely remove this error message as well, it may neither a 
exact resolution
nor some one will take care. Just report the error qemu_rdma_alloc_pd_cq() tell 
us.

Anyway

Reviewed-by: Li Zhijian <lizhijian@fujitsu.com>


>           goto err_rdma_source_init;
>       }