Once again. There’s no point of implementation speculating what will happen to the packet after the pull/push operation. Which L2/L3/L4/… offsets are going to be changed and in which direction? Between which headers the application is going to add/remove layers? What header are moved? What happens next in the chain? What offsets really need an update? Application has all that knowledge and can do only those updates that are needed. We keep it simple – if application modifies the packet it is responsible to maintain metadata offsets accurate.
-Petri From: ext Bill Fischofer [mailto:[email protected]] Sent: Wednesday, December 17, 2014 2:06 PM To: Savolainen, Petri (NSN - FI/Espoo) Cc: Petri Savolainen; lng-odp-forward Subject: Re: [lng-odp] [PATCH] Remove packet l2/l3/l4 offset adjustments You are correct that the API states this. What others are pointing out are the non-intutive implications of choosing to define the API this way. You've not provided a convincing rationale for making this choice. While you can assert your right not to do so, it would be helpful to others if you did. On Wed, Dec 17, 2014 at 5:51 AM, Savolainen, Petri (NSN - FI/Espoo) <[email protected]<mailto:[email protected]>> wrote: The API says already: “Operation does not modify packet segmentation or move data. Handles and pointers remain valid. User is responsible to update packet meta-data offsets when needed.” If application modifies packet headers (adds/removes/changes them), it must update those offsets that it or some other block after it in the chain cares about (reloads from the packet). It may leave some offsets unchanged because it knows that those are not needed any more. Some more words can be added, if the current text is not clear enough. The current implementation does not implement the spec. This patch fixes that issue. -Petri From: ext Bill Fischofer [mailto:[email protected]<mailto:[email protected]>] Sent: Wednesday, December 17, 2014 1:33 PM To: Petri Savolainen Cc: lng-odp-forward Subject: Re: [lng-odp] [PATCH] Remove packet l2/l3/l4 offset adjustments If we do this we really need a documentation note that says: Note: After doing a head push/pull, applications cannot use routines like odp_packet_l3_ptr(), etc., until they make appropriate calls to odp_packet_l3_offset_set(), etc., to reflect the previous operation. Otherwise they will receive pointers to incorrect areas of the packet. On Wed, Dec 17, 2014 at 3:12 AM, Petri Savolainen <[email protected]<mailto:[email protected]>> wrote: Packet head push/pull calls do not automatically adjust metadata offsets, only data pointer and headroom. Signed-off-by: Petri Savolainen <[email protected]<mailto:[email protected]>> --- platform/linux-generic/include/odp_packet_internal.h | 8 -------- 1 file changed, 8 deletions(-) diff --git a/platform/linux-generic/include/odp_packet_internal.h b/platform/linux-generic/include/odp_packet_internal.h index a0eff30..18e69b3 100644 --- a/platform/linux-generic/include/odp_packet_internal.h +++ b/platform/linux-generic/include/odp_packet_internal.h @@ -192,24 +192,16 @@ static inline void *packet_map(odp_packet_hdr_t *pkt_hdr, pkt_hdr->headroom + pkt_hdr->frame_len); } -#define pull_offset(x, len) (x = x < len ? 0 : x - len) - static inline void push_head(odp_packet_hdr_t *pkt_hdr, size_t len) { pkt_hdr->headroom -= len; pkt_hdr->frame_len += len; - pkt_hdr->l2_offset += len; - pkt_hdr->l3_offset += len; - pkt_hdr->l4_offset += len; } static inline void pull_head(odp_packet_hdr_t *pkt_hdr, size_t len) { pkt_hdr->headroom += len; pkt_hdr->frame_len -= len; - pull_offset(pkt_hdr->l2_offset, len); - pull_offset(pkt_hdr->l3_offset, len); - pull_offset(pkt_hdr->l4_offset, len); } static inline void push_tail(odp_packet_hdr_t *pkt_hdr, size_t len) -- 2.2.0 _______________________________________________ lng-odp mailing list [email protected]<mailto:[email protected]> http://lists.linaro.org/mailman/listinfo/lng-odp
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