{"id":208397,"date":"2025-09-08T16:49:03","date_gmt":"2025-09-08T08:49:03","guid":{"rendered":"https:\/\/www.server.hk\/blog\/?p=208397"},"modified":"2025-09-08T16:49:03","modified_gmt":"2025-09-08T08:49:03","slug":"%e4%bc%98%e5%8c%96-linux-%e5%86%85%e6%a0%b8%e7%bd%91%e7%bb%9c%e6%95%b0%e6%8d%ae%e5%8c%85%e5%8f%91%e9%80%81%e4%bb%a5%e6%8f%90%e5%8d%87%e6%80%a7%e8%83%bd","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/208397\/","title":{"rendered":"\u4f18\u5316 Linux \u5185\u6838\u7f51\u7edc\u6570\u636e\u5305\u53d1\u9001\u4ee5\u63d0\u5347\u6027\u80fd"},"content":{"rendered":"<p dir=\"auto\">Linux \u5185\u6838\u7684\u7f51\u7edc\u534f\u8bae\u6808\u662f\u5b9e\u73b0\u9ad8\u6548\u6570\u636e\u901a\u4fe1\u7684\u6838\u5fc3\u7ec4\u6210\u90e8\u5206\uff0c\u5c24\u5176\u5728\u6570\u636e\u5305\u53d1\u9001\u8fc7\u7a0b\u4e2d\u53d1\u6325\u7740\u5173\u952e\u4f5c\u7528\u3002\u672c\u6587\u6df1\u5165\u63a2\u8ba8\u4e86\u6570\u636e\u5305\u53d1\u9001\u7684\u673a\u5236\uff0c\u91cd\u70b9\u5206\u6790\u4e86 ip_queue_xmit \u548c ip_fragment \u51fd\u6570\uff0c\u4ee5\u53ca\u5b83\u4eec\u4e0e\u4e0b\u5c42\u534f\u8bae\u7684\u534f\u4f5c\u65b9\u5f0f\u3002\u6587\u7ae0\u7ed3\u6784\u6e05\u6670\uff0c\u5185\u5bb9\u5168\u9762\u4e14\u6280\u672f\u51c6\u786e\uff0c\u65e8\u5728\u4e3a IT \u4e13\u4e1a\u4eba\u58eb\u63d0\u4f9b\u5b9e\u7528\u4fe1\u606f\uff0c\u540c\u65f6\u4f18\u5316\u641c\u7d22\u5f15\u64ce\u53ef\u89c1\u6027\u3002<\/p>\n<h2 dir=\"auto\">\u6570\u636e\u5305\u53d1\u9001\u6d41\u7a0b\u89e3\u6790<\/h2>\n<p dir=\"auto\">Linux \u5185\u6838\u4e2d\u7684\u6570\u636e\u5305\u53d1\u9001\u91c7\u7528\u5206\u5c42\u8bbe\u8ba1\uff0c\u4ece\u7f51\u7edc\u5c42\u9010\u7ea7\u4f20\u9012\u5230\u94fe\u8def\u5c42\uff0c\u6700\u7ec8\u5230\u8fbe\u7269\u7406\u5c42\u3002\u8fd9\u4e00\u8fc7\u7a0b\u786e\u4fdd\u4e86\u6570\u636e\u5728\u7f51\u7edc\u4e2d\u7684\u53ef\u9760\u3001\u9ad8\u6548\u4f20\u8f93\uff0c\u6d89\u53ca\u6570\u636e\u5305\u9a8c\u8bc1\u3001\u5206\u7247\u548c\u786c\u4ef6\u9a71\u52a8\u8f6c\u53d1\u7b49\u4efb\u52a1\u3002\u4ee5\u4e0b\u5c06\u8be6\u7ec6\u4ecb\u7ecd\u76f8\u5173\u6838\u5fc3\u51fd\u6570\u7684\u804c\u8d23\u53ca\u5176\u4ea4\u4e92\u65b9\u5f0f\u3002<\/p>\n<h3 dir=\"auto\">ip_queue_xmit \u51fd\u6570\u5728\u6570\u636e\u5305\u53d1\u9001\u4e2d\u7684\u4f5c\u7528<\/h3>\n<p dir=\"auto\">ip_queue_xmit \u51fd\u6570\u662f\u7f51\u7edc\u5c42\u7684\u6838\u5fc3\u7ec4\u4ef6\uff0c\u8d1f\u8d23\u5c06 IP \u6570\u636e\u5305\u52a0\u5165\u53d1\u9001\u961f\u5217\u5e76\u8fdb\u884c\u4f20\u8f93\u3002\u5b83\u6267\u884c\u591a\u9879\u5173\u952e\u4efb\u52a1\uff0c\u4ee5\u786e\u4fdd\u6570\u636e\u5305\u9ad8\u6548\u3001\u53ef\u9760\u5730\u53d1\u9001\u3002<\/p>\n<h4 dir=\"auto\">ip_queue_xmit \u7684\u4e3b\u8981\u804c\u8d23<\/h4>\n<ul dir=\"auto\">\n<li><strong>\u6570\u636e\u5305\u9a8c\u8bc1<\/strong>\uff1a\u68c0\u67e5\u53d1\u9001\u8bbe\u5907\u548c\u6570\u636e\u5305\u7684\u5408\u6cd5\u6027\uff0c\u907f\u514d\u4f20\u8f93\u9519\u8bef\u3002<\/li>\n<li><strong>\u9632\u706b\u5899\u8fc7\u6ee4<\/strong>\uff1a\u6839\u636e\u9632\u706b\u5899\u89c4\u5219\u5bf9\u6570\u636e\u5305\u8fdb\u884c\u5b89\u5168\u68c0\u67e5\u3002<\/li>\n<li><strong>\u5206\u7247\u68c0\u67e5<\/strong>\uff1a\u5224\u65ad\u6570\u636e\u5305\u5927\u5c0f\u662f\u5426\u8d85\u8fc7\u6700\u5927\u4f20\u8f93\u5355\u5143\uff08MTU\uff09\uff0c\u51b3\u5b9a\u662f\u5426\u9700\u8981\u5206\u7247\u3002<\/li>\n<li><strong>\u6570\u636e\u5305\u7f13\u5b58<\/strong>\uff1a\u4e3a TCP \u7b49\u53ef\u9760\u534f\u8bae\u7f13\u5b58\u6570\u636e\u5305\uff0c\u4ee5\u652f\u6301\u91cd\u4f20\u3002<\/li>\n<li><strong>\u591a\u64ad\u4e0e\u5e7f\u64ad\u5904\u7406<\/strong>\uff1a\u7ba1\u7406\u591a\u64ad\u548c\u5e7f\u64ad\u6570\u636e\u5305\u7684\u672c\u5730\u56de\u9001\u3002<\/li>\n<li><strong>\u94fe\u8def\u5c42\u8f6c\u53d1<\/strong>\uff1a\u901a\u8fc7 dev_queue_xmit \u5c06\u6570\u636e\u5305\u4f20\u9012\u81f3\u94fe\u8def\u5c42\u5904\u7406\u3002<\/li>\n<\/ul>\n<h4 dir=\"auto\">\u5b9e\u73b0\u7ec6\u8282<\/h4>\n<p dir=\"auto\">\u8be5\u51fd\u6570\u63a5\u6536\u5957\u63a5\u5b57\uff08sk\uff09\u3001\u7f51\u7edc\u8bbe\u5907\uff08dev\uff09\u3001\u6570\u636e\u5305\u7f13\u51b2\u533a\uff08skb\uff09\u4ee5\u53ca\u63a7\u5236\u7f13\u5b58\u884c\u4e3a\u7684 free \u6807\u5fd7\u7b49\u53c2\u6570\u3002\u5176\u5de5\u4f5c\u6d41\u7a0b\u6982\u8ff0\u5982\u4e0b\uff1a<\/p>\n<ol dir=\"auto\">\n<li><strong>\u8bbe\u5907\u4e0e\u6570\u636e\u5305\u9a8c\u8bc1<\/strong>\uff1a\n<ul dir=\"auto\">\n<li>\u786e\u8ba4\u8bbe\u5907\u662f\u5426\u6709\u6548\uff0c\u82e5\u65e0\u6548\u5219\u8bb0\u5f55\u9519\u8bef\u5e76\u9000\u51fa\u3002<\/li>\n<li>\u4f7f\u7528 IS_SKB \u68c0\u67e5\u6570\u636e\u5305\u7ed3\u6784\u7684\u5b8c\u6574\u6027\u3002<\/li>\n<\/ul>\n<\/li>\n<li><strong>\u5934\u90e8\u4e0e\u957f\u5ea6\u8bbe\u7f6e<\/strong>\uff1a\n<ul dir=\"auto\">\n<li>\u4f7f\u7528 jiffies \u8bbe\u7f6e\u6570\u636e\u5305\u53d1\u9001\u65f6\u95f4\u3002<\/li>\n<li>\u8df3\u8fc7 MAC \u5934\u90e8\u5b9a\u4f4d IP \u5934\u90e8\uff0c\u5e76\u8ba1\u7b97 IP \u6570\u636e\u62a5\u603b\u957f\u5ea6\u3002<\/li>\n<\/ul>\n<\/li>\n<li><strong>\u9632\u706b\u5899\u4e0e\u5206\u7247\u5904\u7406<\/strong>\uff1a\n<ul dir=\"auto\">\n<li>\u6267\u884c\u9632\u706b\u5899\u89c4\u5219\u68c0\u67e5\uff0c\u8fc7\u6ee4\u4e0d\u7b26\u5408\u8981\u6c42\u7684\u6570\u636e\u5305\u3002<\/li>\n<li>\u4e3a\u975e\u5206\u7247\u6570\u636e\u5305\u5206\u914d\u552f\u4e00 ID\uff0c\u5206\u7247\u6570\u636e\u5305\u5219\u4fdd\u6301\u76f8\u540c ID\u3002<\/li>\n<li>\u82e5\u6570\u636e\u5305\u5927\u5c0f\u8d85\u8fc7 MTU\uff0c\u5219\u8c03\u7528 ip_fragment \u8fdb\u884c\u5206\u7247\u3002<\/li>\n<\/ul>\n<\/li>\n<li><strong>\u7f13\u5b58\u4e0e\u4f20\u8f93<\/strong>\uff1a\n<ul dir=\"auto\">\n<li>\u82e5 free \u4e3a 0\uff0c\u5219\u7f13\u5b58\u6570\u636e\u5305\u4ee5\u652f\u6301\u91cd\u4f20\uff0c\u5e76\u589e\u52a0 sk-&gt;packets_out \u8ba1\u6570\u3002<\/li>\n<li>\u82e5\u8bbe\u5907\u6b63\u5e38\u5de5\u4f5c\uff0c\u5219\u901a\u8fc7 dev_queue_xmit \u5c06\u6570\u636e\u5305\u8f6c\u53d1\u81f3\u94fe\u8def\u5c42\u3002<\/li>\n<\/ul>\n<\/li>\n<li><strong>\u591a\u64ad\u4e0e\u5e7f\u64ad\u5904\u7406<\/strong>\uff1a\n<ul dir=\"auto\">\n<li>\u5bf9\u591a\u64ad\u6216\u5e7f\u64ad\u6570\u636e\u5305\u8fdb\u884c\u672c\u5730\u56de\u9001\u3002<\/li>\n<li>\u82e5 TTL \u4e3a 0\uff0c\u5219\u4e22\u5f03\u6570\u636e\u5305\uff0c\u9632\u6b62\u8f6c\u53d1\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n<h4 dir=\"auto\">\u4ee3\u7801\u793a\u4f8b\uff1a\u7b80\u5316\u7684 ip_queue_xmit \u5de5\u4f5c\u6d41\u7a0b<\/h4>\n<div dir=\"auto\">\n<div data-testid=\"code-block\">\n<div>c<\/div>\n<div>\n<div>\n<div><\/div>\n<\/div>\n<\/div>\n<div>\n<pre tabindex=\"0\"><code>void ip_queue_xmit(struct sock *sk, struct device *dev, struct sk_buff *skb, int free) {\r\n    struct iphdr *iph = (struct iphdr *)(skb-&gt;data + dev-&gt;hard_header_len);\r\n    skb-&gt;dev = dev;\r\n    skb-&gt;ip_hdr = iph;\r\n    iph-&gt;tot_len = ntohs(skb-&gt;len - dev-&gt;hard_header_len);\r\n\r\n    \/\/ \u9632\u706b\u5899\u68c0\u67e5\r\n    if (ip_fw_chk(iph, dev, ip_fw_blk_chain, ip_fw_blk_policy, 0) != 1)\r\n        return;\r\n\r\n    \/\/ \u4e3a\u975e\u5206\u7247\u6570\u636e\u5305\u5206\u914d ID\r\n    if (free != 2)\r\n        iph-&gt;id = htons(ip_id_count++);\r\n\r\n    \/\/ \u9700\u8981\u65f6\u8fdb\u884c\u5206\u7247\r\n    if (skb-&gt;len &gt; dev-&gt;mtu + dev-&gt;hard_header_len) {\r\n        ip_fragment(sk, skb, dev, 0);\r\n        kfree_skb(skb, FREE_WRITE);\r\n        return;\r\n    }\r\n\r\n    \/\/ \u8ba1\u7b97\u6821\u9a8c\u548c\u5e76\u8f6c\u53d1\u81f3\u94fe\u8def\u5c42\r\n    ip_send_check(iph);\r\n    if (dev-&gt;flags &amp; IFF_UP)\r\n        dev_queue_xmit(skb, dev, sk ? sk-&gt;priority : SOPRI_NORMAL);\r\n    else\r\n        kfree_skb(skb, FREE_WRITE);\r\n}<\/code><\/pre>\n<\/div>\n<div><\/div>\n<div><\/div>\n<\/div>\n<\/div>\n<h3 dir=\"auto\">\u4f7f\u7528 ip_fragment \u8fdb\u884c\u6570\u636e\u5305\u5206\u7247<\/h3>\n<p dir=\"auto\">\u5f53\u6570\u636e\u5305\u5927\u5c0f\u8d85\u8fc7 MTU \u65f6\uff0cip_fragment \u51fd\u6570\u8d1f\u8d23\u5c06\u5176\u62c6\u5206\u4e3a\u66f4\u5c0f\u7684\u7247\u6bb5\uff0c\u786e\u4fdd\u6bcf\u4e2a\u7247\u6bb5\u7b26\u5408\u8bbe\u5907 MTU \u8981\u6c42\uff0c\u540c\u65f6\u4fdd\u6301\u6570\u636e\u5b8c\u6574\u6027\u3002<\/p>\n<h4 dir=\"auto\">\u5206\u7247\u5904\u7406\u6d41\u7a0b<\/h4>\n<ul dir=\"auto\">\n<li><strong>\u5934\u90e8\u8bbe\u7f6e<\/strong>\uff1a\u8ba1\u7b97 IP \u5934\u90e8\u548c MAC \u5934\u90e8\u7684\u957f\u5ea6\uff0c\u786e\u5b9a\u53ef\u7528\u6570\u636e\u7a7a\u95f4\u3002<\/li>\n<li><strong>\u5206\u7247\u68c0\u67e5<\/strong>\uff1a\u68c0\u67e5\u662f\u5426\u5141\u8bb8\u5206\u7247\uff08\u901a\u8fc7\u201c\u7981\u6b62\u5206\u7247\u201d\u6807\u5fd7\uff09\u3002<\/li>\n<li><strong>\u5206\u7247\u521b\u5efa<\/strong>\uff1a\n<ul dir=\"auto\">\n<li>\u4e3a\u6bcf\u4e2a\u5206\u7247\u5206\u914d\u65b0\u7684 sk_buff \u7ed3\u6784\u3002<\/li>\n<li>\u590d\u5236\u539f\u59cb\u5934\u90e8\u548c\u90e8\u5206\u6570\u636e\u8f7d\u8377\u3002<\/li>\n<li>\u8bbe\u7f6e\u5206\u7247\u504f\u79fb\u91cf\u548c\u6807\u5fd7\uff08\u5982\u975e\u6700\u540e\u4e00\u4e2a\u5206\u7247\u7684\u201c\u66f4\u591a\u5206\u7247\u201d\u6807\u5fd7\uff09\u3002<\/li>\n<\/ul>\n<\/li>\n<li><strong>\u4f20\u8f93<\/strong>\uff1a\u901a\u8fc7 ip_queue_xmit \u5c06\u6bcf\u4e2a\u5206\u7247\u52a0\u5165\u53d1\u9001\u961f\u5217\u3002<\/li>\n<\/ul>\n<h4 dir=\"auto\">\u5173\u952e\u6ce8\u610f\u4e8b\u9879<\/h4>\n<ul dir=\"auto\">\n<li><strong>\u6548\u7387\u6743\u8861<\/strong>\uff1a\u6bcf\u4e2a\u5206\u7247\u9700\u9644\u52a0 IP \u5934\u90e8\uff0c\u964d\u4f4e\u4f20\u8f93\u6548\u7387\uff0c\u4f46\u8fd9\u662f\u5fc5\u8981\u63aa\u65bd\u3002<\/li>\n<li><strong>\u5206\u7247\u5bf9\u9f50<\/strong>\uff1a\u786e\u4fdd\u5206\u7247\u6570\u636e\u957f\u5ea6\u4e3a 8 \u7684\u500d\u6570\uff0c\u4ee5\u6ee1\u8db3\u534f\u8bae\u8981\u6c42\u3002<\/li>\n<li><strong>\u9519\u8bef\u5904\u7406<\/strong>\uff1a\u82e5\u7981\u6b62\u5206\u7247\u6216\u5206\u914d\u5931\u8d25\uff0c\u5219\u53d1\u9001 ICMP \u9519\u8bef\u3002<\/li>\n<\/ul>\n<h4 dir=\"auto\">\u4ee3\u7801\u793a\u4f8b\uff1a\u7b80\u5316\u7684 ip_fragment \u5de5\u4f5c\u6d41\u7a0b<\/h4>\n<div dir=\"auto\">\n<div data-testid=\"code-block\">\n<div>c<\/div>\n<div>\n<div>\n<div><\/div>\n<\/div>\n<\/div>\n<div>\n<pre tabindex=\"0\"><code>void ip_fragment(struct sock *sk, struct sk_buff *skb, struct device *dev, int is_frag) {\r\n    struct iphdr *iph = (struct iphdr *)(skb-&gt;data + dev-&gt;hard_header_len);\r\n    int hlen = iph-&gt;ihl * sizeof(unsigned long);\r\n    int mtu = dev-&gt;mtu - hlen;\r\n    int left = ntohs(iph-&gt;tot_len) - hlen;\r\n    unsigned char *ptr = skb-&gt;data + hlen + dev-&gt;hard_header_len;\r\n    int offset = is_frag &amp; 2 ? (ntohs(iph-&gt;frag_off) &amp; 0x1fff) &lt;&lt; 3 : 0;\r\n\r\n    if (ntohs(iph-&gt;frag_off) &amp; IP_DF) {\r\n        icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, dev-&gt;mtu, dev);\r\n        return;\r\n    }\r\n\r\n    while (left &gt; 0) {\r\n        int len = left &gt; mtu ? mtu : left;\r\n        if (len &lt; left)\r\n            len = (len \/ 8) * 8;\r\n\r\n        struct sk_buff *skb2 = alloc_skb(len + hlen + dev-&gt;hard_header_len, GFP_ATOMIC);\r\n        if (!skb2) {\r\n            ip_statistics.IpFragFails++;\r\n            return;\r\n        }\r\n\r\n        memcpy(skb2-&gt;data, skb-&gt;data, hlen + dev-&gt;hard_header_len);\r\n        memcpy(skb2-&gt;data + hlen + dev-&gt;hard_header_len, ptr, len);\r\n        skb2-&gt;len = len + hlen + dev-&gt;hard_header_len;\r\n        iph = (struct iphdr *)(skb2-&gt;data + dev-&gt;hard_header_len);\r\n        iph-&gt;frag_off = htons(offset &gt;&gt; 3);\r\n        if (left &gt; len)\r\n            iph-&gt;frag_off |= htons(IP_MF);\r\n\r\n        ip_queue_xmit(sk, dev, skb2, 2);\r\n        ptr += len;\r\n        offset += len;\r\n        left -= len;\r\n    }\r\n}<\/code><\/pre>\n<\/div>\n<div><\/div>\n<div><\/div>\n<\/div>\n<\/div>\n<h3 dir=\"auto\">\u94fe\u8def\u5c42\u5904\u7406\uff1adev_queue_xmit<\/h3>\n<p dir=\"auto\">dev_queue_xmit \u51fd\u6570\u4f5c\u4e3a\u7f51\u7edc\u5c42\u4e0e\u94fe\u8def\u5c42\u7684\u6865\u6881\uff0c\u8d1f\u8d23\u5c06\u6570\u636e\u5305\u4f20\u9012\u81f3\u7269\u7406\u5c42\u3002<\/p>\n<h4 dir=\"auto\">\u4e3b\u8981\u529f\u80fd<\/h4>\n<ul dir=\"auto\">\n<li><strong>\u8bbe\u5907\u9a8c\u8bc1<\/strong>\uff1a\u786e\u4fdd\u76ee\u6807\u8bbe\u5907\u6709\u6548\u4e14\u5904\u4e8e\u5de5\u4f5c\u72b6\u6001\u3002<\/li>\n<li><strong>\u5730\u5740\u89e3\u6790<\/strong>\uff1a\u82e5\u94fe\u8def\u5c42\u5730\u5740\u672a\u89e3\u6790\uff0c\u5219\u901a\u8fc7 ARP \u5b8c\u6210\u89e3\u6790\u3002<\/li>\n<li><strong>\u961f\u5217\u7ba1\u7406<\/strong>\uff1a\u6839\u636e\u4f18\u5148\u7ea7\u5904\u7406\u6570\u636e\u5305\u961f\u5217\uff0c\u652f\u6301\u91cd\u4f20\u6216\u65b0\u6570\u636e\u5305\u3002<\/li>\n<li><strong>\u9a71\u52a8\u4ea4\u4e92<\/strong>\uff1a\u8c03\u7528\u8bbe\u5907\u9a71\u52a8\u7684 hard_start_xmit \u51fd\u6570\uff0c\u5c06\u6570\u636e\u5305\u53d1\u9001\u81f3\u786c\u4ef6\u3002<\/li>\n<\/ul>\n<h4 dir=\"auto\">\u5de5\u4f5c\u6d41\u7a0b<\/h4>\n<ol dir=\"auto\">\n<li><strong>\u9501\u5b9a\u4e0e\u9a8c\u8bc1<\/strong>\uff1a\n<ul dir=\"auto\">\n<li>\u5bf9\u6570\u636e\u5305\u7f13\u51b2\u533a\u52a0\u9501\uff0c\u9632\u6b62\u5e76\u53d1\u4fee\u6539\u3002<\/li>\n<li>\u9a8c\u8bc1\u8bbe\u5907\u548c\u6570\u636e\u5305\u7684\u5b8c\u6574\u6027\u3002<\/li>\n<\/ul>\n<\/li>\n<li><strong>\u5730\u5740\u89e3\u6790<\/strong>\uff1a\n<ul dir=\"auto\">\n<li>\u82e5\u94fe\u8def\u5c42\u5730\u5740\u672a\u89e3\u6790\uff0c\u542f\u52a8 ARP \u89e3\u6790\u6d41\u7a0b\uff0c\u63a8\u8fdf\u53d1\u9001\u3002<\/li>\n<\/ul>\n<\/li>\n<li><strong>\u961f\u5217\u5904\u7406<\/strong>\uff1a\n<ul dir=\"auto\">\n<li>\u6839\u636e\u4f18\u5148\u7ea7\u5c06\u6570\u636e\u5305\u52a0\u5165\u8bbe\u5907\u961f\u5217\uff0c\u652f\u6301\u4e3b\u4ece\u8bbe\u5907\u8d1f\u8f7d\u5747\u8861\u3002<\/li>\n<li>\u7ba1\u7406\u91cd\u4f20\u6570\u636e\u5305\u7684\u961f\u5217\u4f4d\u7f6e\u3002<\/li>\n<\/ul>\n<\/li>\n<li><strong>\u6570\u636e\u5305\u53d1\u9001<\/strong>\uff1a\n<ul dir=\"auto\">\n<li>\u82e5\u8bbe\u5907\u6b63\u5e38\uff0c\u5219\u5c06\u6570\u636e\u5305\u4f20\u9012\u81f3\u9a71\u52a8\u7a0b\u5e8f\u3002<\/li>\n<li>\u82e5\u8bbe\u5907\u4e0d\u53ef\u7528\uff0c\u5219\u4e22\u5f03\u6570\u636e\u5305\uff0c\u89e6\u53d1\u53ef\u9760\u534f\u8bae\u7684\u91cd\u4f20\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n<h4 dir=\"auto\">\u4ee3\u7801\u793a\u4f8b\uff1a\u7b80\u5316\u7684 dev_queue_xmit \u5de5\u4f5c\u6d41\u7a0b<\/h4>\n<div dir=\"auto\">\n<div data-testid=\"code-block\">\n<div>c<\/div>\n<div>\n<div>\n<div><\/div>\n<\/div>\n<\/div>\n<div>\n<pre tabindex=\"0\"><code>void dev_queue_xmit(struct sk_buff *skb, struct device *dev, int pri) {\r\n    if (!dev) {\r\n        printk(\"dev_queue_xmit: dev = NULL\\n\");\r\n        return;\r\n    }\r\n\r\n    skb-&gt;dev = dev;\r\n    if (!skb-&gt;arp &amp;&amp; dev-&gt;rebuild_header(skb-&gt;data, dev, skb-&gt;raddr, skb))\r\n        return;\r\n\r\n    if (dev-&gt;flags &amp; IFF_UP) {\r\n        dev-&gt;hard_start_xmit(skb, dev);\r\n    } else {\r\n        kfree_skb(skb, FREE_WRITE);\r\n    }\r\n}<\/code><\/pre>\n<\/div>\n<div><\/div>\n<div><\/div>\n<\/div>\n<\/div>\n<h2 dir=\"auto\">\u4f18\u5316\u6570\u636e\u5305\u53d1\u9001\u7684\u6700\u4f73\u5b9e\u8df5<\/h2>\n<p dir=\"auto\">\u4e3a\u63d0\u5347 Linux \u5185\u6838\u6570\u636e\u5305\u53d1\u9001\u6548\u7387\uff0c\u53ef\u53c2\u8003\u4ee5\u4e0b\u5efa\u8bae\uff1a<\/p>\n<ul dir=\"auto\">\n<li><strong>\u51cf\u5c11\u5206\u7247<\/strong>\uff1a\u8c03\u6574 MTU \u8bbe\u7f6e\u4ee5\u964d\u4f4e\u5206\u7247\u9700\u6c42\uff0c\u63d0\u5347\u541e\u5410\u91cf\u3002<\/li>\n<li><strong>\u4f18\u5316\u9632\u706b\u5899\u89c4\u5219<\/strong>\uff1a\u7cbe\u7b80\u9632\u706b\u5899\u68c0\u67e5\uff0c\u51cf\u5c11\u5904\u7406\u5f00\u9500\u3002<\/li>\n<li><strong>\u5229\u7528\u786c\u4ef6\u5378\u8f7d<\/strong>\uff1a\u4f7f\u7528\u652f\u6301\u6821\u9a8c\u548c\u5378\u8f7d\u7684\u7f51\u5361\uff0c\u51cf\u8f7b CPU \u8d1f\u62c5\u3002<\/li>\n<li><strong>\u76d1\u63a7\u7edf\u8ba1\u6570\u636e<\/strong>\uff1a\u901a\u8fc7 ip_statistics\uff08\u5982 IpOutRequests\u3001IpFragFails\uff09\u8ffd\u8e2a\u6027\u80fd\u74f6\u9888\u3002<\/li>\n<\/ul>\n<h2 dir=\"auto\">\u7ed3\u8bba<\/h2>\n<p dir=\"auto\">Linux \u5185\u6838\u7f51\u7edc\u534f\u8bae\u6808\u901a\u8fc7\u6a21\u5757\u5316\u3001\u5206\u5c42\u8bbe\u8ba1\u5b9e\u73b0\u4e86\u9ad8\u6548\u7684\u6570\u636e\u5305\u53d1\u9001\uff0cip_queue_xmit\u3001ip_fragment \u548c dev_queue_xmit \u51fd\u6570\u5728\u5176\u4e2d\u626e\u6f14\u4e86\u5173\u952e\u89d2\u8272\u3002\u8fd9\u4e9b\u51fd\u6570\u901a\u8fc7\u9a8c\u8bc1\u3001\u5206\u7247\u548c\u8f6c\u53d1\u6570\u636e\u5305\uff0c\u786e\u4fdd\u4e86\u7f51\u7edc\u901a\u4fe1\u7684\u53ef\u9760\u6027\u548c\u9ad8\u6548\u6027\u3002\u6df1\u5165\u7406\u89e3\u8fd9\u4e9b\u673a\u5236\u6709\u52a9\u4e8e\u7cfb\u7edf\u7ba1\u7406\u5458\u548c\u5f00\u53d1\u8005\u4f18\u5316\u7f51\u7edc\u6027\u80fd\u5e76\u6709\u6548\u6392\u67e5\u95ee\u9898\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Linux \u5185\u6838\u7684\u7f51\u7edc\u534f\u8bae\u6808\u662f\u5b9e&#46;&#46;&#46;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4924],"tags":[],"class_list":["post-208397","post","type-post","status-publish","format-standard","hentry","category-setup-tutorials"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/208397","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/comments?post=208397"}],"version-history":[{"count":0,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/208397\/revisions"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=208397"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=208397"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=208397"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}