Eric Lee / smarc-fsl-linux-kernel

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samples/bpf/tcp_basertt_kern.c 1.69 KB
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c890063e4   Lawrence Brakmo   bpf: sample BPF_S... 
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  /* Copyright (c) 2017 Facebook
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of version 2 of the GNU General Public
   * License as published by the Free Software Foundation.
   *
   * BPF program to set base_rtt to 80us when host is running TCP-NV and
   * both hosts are in the same datacenter (as determined by IPv6 prefix).
   *
ea9b63620   Jakub Kicinski   samples: bpf: rem... 
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   * Use "bpftool cgroup attach $cg sock_ops $prog" to load this BPF program.
c890063e4   Lawrence Brakmo   bpf: sample BPF_S... 
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   */
  
  #include <uapi/linux/bpf.h>
  #include <uapi/linux/tcp.h>
  #include <uapi/linux/if_ether.h>
  #include <uapi/linux/if_packet.h>
  #include <uapi/linux/ip.h>
  #include <linux/socket.h>
7cf245a37   Toke Høiland-Jørgensen   samples/bpf: Use ... 
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  #include <bpf/bpf_helpers.h>
  #include <bpf/bpf_endian.h>
c890063e4   Lawrence Brakmo   bpf: sample BPF_S... 
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  #define DEBUG 1
c890063e4   Lawrence Brakmo   bpf: sample BPF_S... 
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  SEC("sockops")
  int bpf_basertt(struct bpf_sock_ops *skops)
  {
  	char cong[20];
  	char nv[] = "nv";
  	int rv = 0, n;
  	int op;
  
  	op = (int) skops->op;
  
  #ifdef DEBUG
  	bpf_printk("BPF command: %d
  ", op);
  #endif
  
  	/* Check if both hosts are in the same datacenter. For this
  	 * example they are if the 1st 5.5 bytes in the IPv6 address
  	 * are the same.
  	 */
  	if (skops->family == AF_INET6 &&
  	    skops->local_ip6[0] == skops->remote_ip6[0] &&
  	    (bpf_ntohl(skops->local_ip6[1]) & 0xfff00000) ==
  	    (bpf_ntohl(skops->remote_ip6[1]) & 0xfff00000)) {
  		switch (op) {
  		case BPF_SOCK_OPS_BASE_RTT:
  			n = bpf_getsockopt(skops, SOL_TCP, TCP_CONGESTION,
  					   cong, sizeof(cong));
  			if (!n && !__builtin_memcmp(cong, nv, sizeof(nv)+1)) {
  				/* Set base_rtt to 80us */
  				rv = 80;
  			} else if (n) {
  				rv = n;
  			} else {
  				rv = -1;
  			}
  			break;
  		default:
  			rv = -1;
  		}
  	} else {
  		rv = -1;
  	}
  #ifdef DEBUG
  	bpf_printk("Returning %d
  ", rv);
  #endif
  	skops->reply = rv;
  	return 1;
  }
  char _license[] SEC("license") = "GPL";