rjmcmahon
/
umber-kernel
1
0
Fork 0
Code Issues 1 Pull Requests Packages Projects Releases Wiki Activity

bpf: Allow bpf_xdp_shrink_data to shrink a frag from head and tail 

Move skb_frag_t adjustment into bpf_xdp_shrink_data() and extend its
functionality to be able to shrink an xdp fragment from both head and
tail. In a later patch, bpf_xdp_pull_data() will reuse it to shrink an
xdp fragment from head.

Additionally, in bpf_xdp_frags_shrink_tail(), breaking the loop when
bpf_xdp_shrink_data() returns false (i.e., not releasing the current
fragment) is not necessary as the loop condition, offset > 0, has the
same effect. Remove the else branch to simplify the code.

Signed-off-by: Amery Hung <ameryhung@gmail.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Reviewed-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Link: https://patch.msgid.link/20250922233356.3356453-3-ameryhung@gmail.com
This commit is contained in:
Amery Hung 2025-09-22 16:33:50 -07:00 committed by Martin KaFai Lau
parent 8f12d1137c
commit dea1526fba
2 changed files with 42 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
include/net/xdp_sock_drv.h
View File

@ -160,13 +160,23 @@ static inline struct xdp_buff *xsk_buff_get_frag(const struct xdp_buff *first)
return ret;
}
static inline void xsk_buff_del_tail(struct xdp_buff *tail)
static inline void xsk_buff_del_frag(struct xdp_buff *xdp)
{
struct xdp_buff_xsk *xskb = container_of(tail, struct xdp_buff_xsk, xdp);
struct xdp_buff_xsk *xskb = container_of(xdp, struct xdp_buff_xsk, xdp);
list_del(&xskb->list_node);
}
static inline struct xdp_buff *xsk_buff_get_head(struct xdp_buff *first)
{
struct xdp_buff_xsk *xskb = container_of(first, struct xdp_buff_xsk, xdp);
struct xdp_buff_xsk *frag;
frag = list_first_entry(&xskb->pool->xskb_list, struct xdp_buff_xsk,
list_node);
return &frag->xdp;
}
static inline struct xdp_buff *xsk_buff_get_tail(struct xdp_buff *first)
{
struct xdp_buff_xsk *xskb = container_of(first, struct xdp_buff_xsk, xdp);
@ -389,10 +399,15 @@ static inline struct xdp_buff *xsk_buff_get_frag(const struct xdp_buff *first)
return NULL;
}
static inline void xsk_buff_del_tail(struct xdp_buff *tail)
static inline void xsk_buff_del_frag(struct xdp_buff *xdp)
{
}
static inline struct xdp_buff *xsk_buff_get_head(struct xdp_buff *first)
{
return NULL;
}
static inline struct xdp_buff *xsk_buff_get_tail(struct xdp_buff *first)
{
return NULL;

41
net/core/filter.c
View File

@ -4153,34 +4153,45 @@ static int bpf_xdp_frags_increase_tail(struct xdp_buff *xdp, int offset)
return 0;
}
static void bpf_xdp_shrink_data_zc(struct xdp_buff *xdp, int shrink,
enum xdp_mem_type mem_type, bool release)
static struct xdp_buff *bpf_xdp_shrink_data_zc(struct xdp_buff *xdp, int shrink,
bool tail, bool release)
{
struct xdp_buff *zc_frag = xsk_buff_get_tail(xdp);
struct xdp_buff *zc_frag = tail ? xsk_buff_get_tail(xdp) :
xsk_buff_get_head(xdp);
if (release) {
xsk_buff_del_tail(zc_frag);
__xdp_return(0, mem_type, false, zc_frag);
xsk_buff_del_frag(zc_frag);
} else {
zc_frag->data_end -= shrink;
if (tail)
zc_frag->data_end -= shrink;
else
zc_frag->data += shrink;
}
return zc_frag;
}
static bool bpf_xdp_shrink_data(struct xdp_buff *xdp, skb_frag_t *frag,
int shrink)
int shrink, bool tail)
{
enum xdp_mem_type mem_type = xdp->rxq->mem.type;
bool release = skb_frag_size(frag) == shrink;
netmem_ref netmem = skb_frag_netmem(frag);
struct xdp_buff *zc_frag = NULL;
if (mem_type == MEM_TYPE_XSK_BUFF_POOL) {
bpf_xdp_shrink_data_zc(xdp, shrink, mem_type, release);
goto out;
netmem = 0;
zc_frag = bpf_xdp_shrink_data_zc(xdp, shrink, tail, release);
}
if (release)
__xdp_return(skb_frag_netmem(frag), mem_type, false, NULL);
if (release) {
__xdp_return(netmem, mem_type, false, zc_frag);
} else {
if (!tail)
skb_frag_off_add(frag, shrink);
skb_frag_size_sub(frag, shrink);
}
out:
return release;
}
@ -4198,12 +4209,8 @@ static int bpf_xdp_frags_shrink_tail(struct xdp_buff *xdp, int offset)
len_free += shrink;
offset -= shrink;
if (bpf_xdp_shrink_data(xdp, frag, shrink)) {
if (bpf_xdp_shrink_data(xdp, frag, shrink, true))
n_frags_free++;
} else {
skb_frag_size_sub(frag, shrink);
break;
}
}
sinfo->nr_frags -= n_frags_free;
sinfo->xdp_frags_size -= len_free;