[ovs-dev] ofproto-dpif-xlate: remove mirror assert

During the revalidation, mirror could be removed. Instead of crash
the process, we can simply skip the deleted mirror.

Fixes: ec7ceaed4f3e ("ofproto-dpif: Modularize mirror code.")
Signed-off-by: lic121 <lic121@chinatelecom.cn>
---
 ofproto/ofproto-dpif-xlate.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

On 4/7/22 15:53, lic121 wrote:
> During the revalidation, mirror could be removed. Instead of crash
> the process, we can simply skip the deleted mirror.
> 
> Fixes: ec7ceaed4f3e ("ofproto-dpif: Modularize mirror code.")
> Signed-off-by: lic121 <lic121@chinatelecom.cn>
> ---
>   ofproto/ofproto-dpif-xlate.c | 10 +++++++---
>   1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/ofproto/ofproto-dpif-xlate.c b/ofproto/ofproto-dpif-xlate.c
> index 5a770f1..33e56c2 100644
> --- a/ofproto/ofproto-dpif-xlate.c
> +++ b/ofproto/ofproto-dpif-xlate.c
> @@ -2142,9 +2142,13 @@ mirror_packet(struct xlate_ctx *ctx, struct xbundle *xbundle,
>           int snaplen;
>   
>           /* Get the details of the mirror represented by the rightmost 1-bit. */
> -        ovs_assert(mirror_get(xbridge->mbridge, raw_ctz(mirrors),
> -                              &vlans, &dup_mirrors,
> -                              &out, &snaplen, &out_vlan));
> +        if (!mirror_get(xbridge->mbridge, raw_ctz(mirrors),
> +                       &vlans, &dup_mirrors,
> +                       &out, &snaplen, &out_vlan)) {
> +            /* Mirror could be deleted during revalidation */
> +            mirrors = zero_rightmost_1bit(mirrors);
> +            continue;
> +        }
>   
>   
>           /* If this mirror selects on the basis of VLAN, and it does not select

I have reproduced the assert and verified this patch fixes it.

The patch looks good to me. My only nit is about the comment, it's a bit 
confusing because this code is executed also in upcall handling, not only on 
revalidation. Something on the lines of the following would be a bit more clear 
IMHO:

/* The mirror got reconfigured before we got to read it's configuration. */

Also, maybe add OVS_UNLIKELY?

Thanks.

On Wed, Apr 27, 2022 at 01:36:48PM +0200, Adrian Moreno wrote:
> 
> 
> On 4/7/22 15:53, lic121 wrote:
> >During the revalidation, mirror could be removed. Instead of crash
> >the process, we can simply skip the deleted mirror.
> >
> >Fixes: ec7ceaed4f3e ("ofproto-dpif: Modularize mirror code.")
> >Signed-off-by: lic121 <lic121@chinatelecom.cn>
> >---
> >  ofproto/ofproto-dpif-xlate.c | 10 +++++++---
> >  1 file changed, 7 insertions(+), 3 deletions(-)
> >
> >diff --git a/ofproto/ofproto-dpif-xlate.c b/ofproto/ofproto-dpif-xlate.c
> >index 5a770f1..33e56c2 100644
> >--- a/ofproto/ofproto-dpif-xlate.c
> >+++ b/ofproto/ofproto-dpif-xlate.c
> >@@ -2142,9 +2142,13 @@ mirror_packet(struct xlate_ctx *ctx, struct xbundle *xbundle,
> >          int snaplen;
> >          /* Get the details of the mirror represented by the rightmost 1-bit. */
> >-        ovs_assert(mirror_get(xbridge->mbridge, raw_ctz(mirrors),
> >-                              &vlans, &dup_mirrors,
> >-                              &out, &snaplen, &out_vlan));
> >+        if (!mirror_get(xbridge->mbridge, raw_ctz(mirrors),
> >+                       &vlans, &dup_mirrors,
> >+                       &out, &snaplen, &out_vlan)) {
> >+            /* Mirror could be deleted during revalidation */
> >+            mirrors = zero_rightmost_1bit(mirrors);
> >+            continue;
> >+        }
> >          /* If this mirror selects on the basis of VLAN, and it does not select
> 
> I have reproduced the assert and verified this patch fixes it.
> 
> The patch looks good to me. My only nit is about the comment, it's a
> bit confusing because this code is executed also in upcall handling,
> not only on revalidation. Something on the lines of the following
> would be a bit more clear IMHO:
> 
> /* The mirror got reconfigured before we got to read it's configuration. */
> 
> Also, maybe add OVS_UNLIKELY?

Thanks for the review, will address the comments in the next version.

> 
> Thanks.
> -- 
> Adrián Moreno
>