Commit 5f116212 authored by Kumar Kartikeya Dwivedi's avatar Kumar Kartikeya Dwivedi Committed by Alexei Starovoitov
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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: default avatarKumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210821002010.845777-11-memxor@gmail.com
parent d771e217

samples/bpf/xdp_sample.bpf.c

+71 −0
Original line number Diff line number Diff line
@@ -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;

}