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samples: bpf: Add BPF support for devmap_xmit tracepoint 

This adds support for the devmap_xmit tracepoint, and its multi device
variant that can be used to obtain streams for each individual
net_device to net_device redirection. This is useful for decomposing
total xmit stats in xdp_monitor.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210821002010.845777-11-memxor@gmail.com
This commit is contained in:
Kumar Kartikeya Dwivedi 2021-08-21 05:49:58 +05:30 committed by Alexei Starovoitov
parent d771e21750
commit 5f116212f4
1 changed files with 71 additions and 0 deletions
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71
samples/bpf/xdp_sample.bpf.c
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@ -11,6 +11,14 @@ array_map redir_err_cnt SEC(".maps");
array_map cpumap_enqueue_cnt SEC(".maps");
array_map cpumap_kthread_cnt SEC(".maps");
array_map exception_cnt SEC(".maps");
array_map devmap_xmit_cnt SEC(".maps");
struct {
__uint(type, BPF_MAP_TYPE_PERCPU_HASH);
__uint(max_entries, 32 * 32);
__type(key, u64);
__type(value, struct datarec);
} devmap_xmit_cnt_multi SEC(".maps");
const volatile int nr_cpus = 0;
@ -193,3 +201,66 @@ int BPF_PROG(tp_xdp_exception, const struct net_device *dev,
return 0;
}
SEC("tp_btf/xdp_devmap_xmit")
int BPF_PROG(tp_xdp_devmap_xmit, const struct net_device *from_dev,
const struct net_device *to_dev, int sent, int drops, int err)
{
struct datarec *rec;
int idx_in, idx_out;
u32 cpu;
idx_in = from_dev->ifindex;
idx_out = to_dev->ifindex;
if (!IN_SET(from_match, idx_in))
return 0;
if (!IN_SET(to_match, idx_out))
return 0;
cpu = bpf_get_smp_processor_id();
rec = bpf_map_lookup_elem(&devmap_xmit_cnt, &cpu);
if (!rec)
return 0;
NO_TEAR_ADD(rec->processed, sent);
NO_TEAR_ADD(rec->dropped, drops);
/* Record bulk events, then userspace can calc average bulk size */
NO_TEAR_INC(rec->info);
/* Record error cases, where no frame were sent */
/* Catch API error of drv ndo_xdp_xmit sent more than count */
if (err || drops < 0)
NO_TEAR_INC(rec->issue);
return 0;
}
SEC("tp_btf/xdp_devmap_xmit")
int BPF_PROG(tp_xdp_devmap_xmit_multi, const struct net_device *from_dev,
const struct net_device *to_dev, int sent, int drops, int err)
{
struct datarec empty = {};
struct datarec *rec;
int idx_in, idx_out;
u64 idx;
idx_in = from_dev->ifindex;
idx_out = to_dev->ifindex;
idx = idx_in;
idx = idx << 32 | idx_out;
if (!IN_SET(from_match, idx_in))
return 0;
if (!IN_SET(to_match, idx_out))
return 0;
bpf_map_update_elem(&devmap_xmit_cnt_multi, &idx, &empty, BPF_NOEXIST);
rec = bpf_map_lookup_elem(&devmap_xmit_cnt_multi, &idx);
if (!rec)
return 0;
NO_TEAR_ADD(rec->processed, sent);
NO_TEAR_ADD(rec->dropped, drops);
NO_TEAR_INC(rec->info);
if (err || drops < 0)
NO_TEAR_INC(rec->issue);
return 0;
}