prestera: matchall: do not rollback if rule exists

If you try to create a 'mirror' ACL rule on a port that already has a
mirror rule, prestera_span_rule_add() will fail with EEXIST error.

This forces rollback procedure which destroys existing mirror rule on
hardware leaving it visible in linux.

Add an explicit check for EEXIST to prevent the deletion of the existing
rule but keep user seeing error message:

$ tc filter add dev sw1p1 ... skip_sw action mirred egress mirror dev sw1p2
$ tc filter add dev sw1p1 ... skip_sw action mirred egress mirror dev sw1p3
RTNETLINK answers: File exists
We have an error talking to the kernel

Fixes: 13defa275eef ("net: marvell: prestera: Add matchall support")
Signed-off-by: Serhiy Boiko <serhiy.boiko@plvision.eu>
Signed-off-by: Maksym Glubokiy <maksym.glubokiy@plvision.eu>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: prestera: manage matchall and flower priorities

matchall rules can be added only to chain 0 and their priorities have
limitations:
- new matchall ingress rule's priority must be higher (lower value)
than any existing flower rule;
- new matchall egress rule's priority must be lower (higher value)
than any existing flower rule.

The opposite works for flower rule adding:
- new flower ingress rule's priority must be lower (higher value)
than any existing matchall rule;
- new flower egress rule's priority must be higher (lower value)
than any existing matchall rule.

This is a hardware limitation and thus must be properly handled in
driver by reporting errors to the user when newly added rule has such a
priority that cannot be installed into the hardware.

To achieve this, the driver must maintain both min/max matchall
priorities for every flower block when user adds/deletes a matchall
rule, as well as both min/max flower priorities for chain 0 for every
adding/deletion of flower rules for chain 0.

Cc: Serhiy Boiko <serhiy.boiko@plvision.eu>
Signed-off-by: Maksym Glubokiy <maksym.glubokiy@plvision.eu>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: prestera: add support for egress traffic mirroring

This enables adding matchall rules for egress:

tc filter add .. egress .. matchall skip_sw \
action mirred egress mirror dev ..

Signed-off-by: Serhiy Boiko <serhiy.boiko@plvision.eu>
Signed-off-by: Maksym Glubokiy <maksym.glubokiy@plvision.eu>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: prestera: acl: extract matchall logic into a separate file

This commit adds more clarity to handling of TC_CLSMATCHALL_REPLACE and
TC_CLSMATCHALL_DESTROY events by calling newly added *_mall_*() handlers
instead of directly calling SPAN API.

This also extracts matchall rules management out of SPAN API since SPAN
is a hardware module which is used to implement 'matchall egress mirred'
action only.

Signed-off-by: Taras Chornyi <tchornyi@marvell.com>
Signed-off-by: Serhiy Boiko <serhiy.boiko@plvision.eu>
Signed-off-by: Maksym Glubokiy <maksym.glubokiy@plvision.eu>
Signed-off-by: David S. Miller <davem@davemloft.net>