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Subjecttcp_recvmsg(): Re: [Bug #11308] tbench regression on each kernel release from 2.6.22 -> 2.6.28

* Ingo Molnar <mingo@elte.hu> wrote:

> 100.000000 total
> ................
> 1.833688 tcp_recvmsg

hits (total: 183368)
.........
ffffffff804bd46e: 882 <tcp_recvmsg>:
ffffffff804bd46e: 882 41 57 push %r15
ffffffff804bd470: 15507 48 89 f7 mov %rsi,%rdi
ffffffff804bd473: 179 41 56 push %r14
ffffffff804bd475: 0 49 89 ce mov %rcx,%r14
ffffffff804bd478: 744 41 55 push %r13
ffffffff804bd47a: 165 41 54 push %r12
ffffffff804bd47c: 0 45 89 c4 mov %r8d,%r12d
ffffffff804bd47f: 692 55 push %rbp
ffffffff804bd480: 178 44 89 cd mov %r9d,%ebp
ffffffff804bd483: 3434 53 push %rbx
ffffffff804bd484: 685 48 89 f3 mov %rsi,%rbx
ffffffff804bd487: 11 48 83 ec 68 sub $0x68,%rsp
ffffffff804bd48b: 949 48 89 54 24 30 mov %rdx,0x30(%rsp)
ffffffff804bd490: 7 e8 e8 e8 ff ff callq ffffffff804bbd7d <lock_sock>
ffffffff804bd495: 1771 8a 43 02 mov 0x2(%rbx),%al
ffffffff804bd498: 6176 3c 0a cmp $0xa,%al
ffffffff804bd49a: 0 0f 84 3a 06 00 00 je ffffffff804bdada <tcp_recvmsg+0x66c>
ffffffff804bd4a0: 3121 31 c0 xor %eax,%eax
ffffffff804bd4a2: 195 45 85 e4 test %r12d,%r12d
ffffffff804bd4a5: 0 75 07 jne ffffffff804bd4ae <tcp_recvmsg+0x40>
ffffffff804bd4a7: 926 48 8b 83 68 01 00 00 mov 0x168(%rbx),%rax
ffffffff804bd4ae: 189 40 f6 c5 01 test $0x1,%bpl
ffffffff804bd4b2: 0 48 89 44 24 58 mov %rax,0x58(%rsp)
ffffffff804bd4b7: 819 0f 85 33 06 00 00 jne ffffffff804bdaf0 <tcp_recvmsg+0x682>
ffffffff804bd4bd: 216 89 e8 mov %ebp,%eax
ffffffff804bd4bf: 0 83 e0 02 and $0x2,%eax
ffffffff804bd4c2: 638 89 44 24 3c mov %eax,0x3c(%rsp)
ffffffff804bd4c6: 177 75 0e jne ffffffff804bd4d6 <tcp_recvmsg+0x68>
ffffffff804bd4c8: 0 48 8d 93 f4 03 00 00 lea 0x3f4(%rbx),%rdx
ffffffff804bd4cf: 661 48 89 54 24 40 mov %rdx,0x40(%rsp)
ffffffff804bd4d4: 195 eb 14 jmp ffffffff804bd4ea <tcp_recvmsg+0x7c>
ffffffff804bd4d6: 0 8b 83 f4 03 00 00 mov 0x3f4(%rbx),%eax
ffffffff804bd4dc: 0 48 8d 4c 24 60 lea 0x60(%rsp),%rcx
ffffffff804bd4e1: 0 48 89 4c 24 40 mov %rcx,0x40(%rsp)
ffffffff804bd4e6: 0 89 44 24 60 mov %eax,0x60(%rsp)
ffffffff804bd4ea: 867 89 ee mov %ebp,%esi
ffffffff804bd4ec: 210 44 89 f2 mov %r14d,%edx
ffffffff804bd4ef: 0 48 89 df mov %rbx,%rdi
ffffffff804bd4f2: 894 81 e6 00 01 00 00 and $0x100,%esi
ffffffff804bd4f8: 192 45 31 ff xor %r15d,%r15d
ffffffff804bd4fb: 0 e8 fc df ff ff callq ffffffff804bb4fc <sock_rcvlowat>
ffffffff804bd500: 853 89 44 24 4c mov %eax,0x4c(%rsp)
ffffffff804bd504: 1857 48 8d 83 a8 00 00 00 lea 0xa8(%rbx),%rax
ffffffff804bd50b: 0 89 e9 mov %ebp,%ecx
ffffffff804bd50d: 595 48 8d 93 10 04 00 00 lea 0x410(%rbx),%rdx
ffffffff804bd514: 263 83 e1 22 and $0x22,%ecx
ffffffff804bd517: 0 83 e5 20 and $0x20,%ebp
ffffffff804bd51a: 601 48 89 44 24 28 mov %rax,0x28(%rsp)
ffffffff804bd51f: 254 48 8d 83 f8 04 00 00 lea 0x4f8(%rbx),%rax
ffffffff804bd526: 2 48 c7 44 24 50 00 00 movq $0x0,0x50(%rsp)
ffffffff804bd52d: 0 00 00
ffffffff804bd52f: 578 48 89 54 24 20 mov %rdx,0x20(%rsp)
ffffffff804bd534: 290 89 4c 24 1c mov %ecx,0x1c(%rsp)
ffffffff804bd538: 1 48 89 44 24 10 mov %rax,0x10(%rsp)
ffffffff804bd53d: 593 89 6c 24 0c mov %ebp,0xc(%rsp)
ffffffff804bd541: 568 66 83 bb 7c 04 00 00 cmpw $0x0,0x47c(%rbx)
ffffffff804bd548: 0 00
ffffffff804bd549: 3956 74 55 je ffffffff804bd5a0 <tcp_recvmsg+0x132>
ffffffff804bd54b: 0 48 8b 54 24 40 mov 0x40(%rsp),%rdx
ffffffff804bd550: 0 8b 83 84 05 00 00 mov 0x584(%rbx),%eax
ffffffff804bd556: 0 3b 02 cmp (%rdx),%eax
ffffffff804bd558: 0 75 46 jne ffffffff804bd5a0 <tcp_recvmsg+0x132>
ffffffff804bd55a: 0 45 85 ff test %r15d,%r15d
ffffffff804bd55d: 0 0f 85 e6 04 00 00 jne ffffffff804bda49 <tcp_recvmsg+0x5db>
ffffffff804bd563: 0 65 48 8b 3c 25 00 00 mov %gs:0x0,%rdi
ffffffff804bd56a: 0 00 00
ffffffff804bd56c: 0 e8 4c e1 ff ff callq ffffffff804bb6bd <signal_pending>
ffffffff804bd571: 0 85 c0 test %eax,%eax
ffffffff804bd573: 0 74 2b je ffffffff804bd5a0 <tcp_recvmsg+0x132>
ffffffff804bd575: 0 48 8b 54 24 58 mov 0x58(%rsp),%rdx
ffffffff804bd57a: 0 41 bf f5 ff ff ff mov $0xfffffff5,%r15d
ffffffff804bd580: 0 48 85 d2 test %rdx,%rdx
ffffffff804bd583: 0 0f 84 c0 04 00 00 je ffffffff804bda49 <tcp_recvmsg+0x5db>
ffffffff804bd589: 0 48 b8 ff ff ff ff ff mov $0x7fffffffffffffff,%rax
ffffffff804bd590: 0 ff ff 7f
ffffffff804bd593: 0 66 41 bf 00 fe mov $0xfe00,%r15w
ffffffff804bd598: 0 48 39 c2 cmp %rax,%rdx
ffffffff804bd59b: 0 e9 89 01 00 00 jmpq ffffffff804bd729 <tcp_recvmsg+0x2bb>
ffffffff804bd5a0: 597 48 8b ab a8 00 00 00 mov 0xa8(%rbx),%rbp
ffffffff804bd5a7: 4601 48 3b 6c 24 28 cmp 0x28(%rsp),%rbp
ffffffff804bd5ac: 1 b8 00 00 00 00 mov $0x0,%eax
ffffffff804bd5b1: 1769 48 0f 44 e8 cmove %rax,%rbp
ffffffff804bd5b5: 473 48 85 ed test %rbp,%rbp
ffffffff804bd5b8: 0 74 76 je ffffffff804bd630 <tcp_recvmsg+0x1c2>
ffffffff804bd5ba: 595 48 8b 4c 24 40 mov 0x40(%rsp),%rcx
ffffffff804bd5bf: 897 8b 55 50 mov 0x50(%rbp),%edx
ffffffff804bd5c2: 89 8b 31 mov (%rcx),%esi
ffffffff804bd5c4: 581 41 89 f5 mov %esi,%r13d
ffffffff804bd5c7: 301 41 29 d5 sub %edx,%r13d
ffffffff804bd5ca: 33 79 10 jns ffffffff804bd5dc <tcp_recvmsg+0x16e>
ffffffff804bd5cc: 0 48 c7 c7 48 d9 6a 80 mov $0xffffffff806ad948,%rdi
ffffffff804bd5d3: 0 31 c0 xor %eax,%eax
ffffffff804bd5d5: 0 e8 9a 97 d7 ff callq ffffffff80236d74 <printk>
ffffffff804bd5da: 0 eb 54 jmp ffffffff804bd630 <tcp_recvmsg+0x1c2>
ffffffff804bd5dc: 584 8b 85 b8 00 00 00 mov 0xb8(%rbp),%eax
ffffffff804bd5e2: 1061 48 8b 95 d0 00 00 00 mov 0xd0(%rbp),%rdx
ffffffff804bd5e9: 1 8a 54 02 0d mov 0xd(%rdx,%rax,1),%dl
ffffffff804bd5ed: 0 88 d0 mov %dl,%al
ffffffff804bd5ef: 876 83 e0 02 and $0x2,%eax
ffffffff804bd5f2: 0 3c 01 cmp $0x1,%al
ffffffff804bd5f4: 0 8b 45 68 mov 0x68(%rbp),%eax
ffffffff804bd5f7: 909 41 83 d5 ff adc $0xffffffffffffffff,%r13d
ffffffff804bd5fb: 0 41 39 c5 cmp %eax,%r13d
ffffffff804bd5fe: 0 0f 82 df 02 00 00 jb ffffffff804bd8e3 <tcp_recvmsg+0x475>
ffffffff804bd604: 0 80 e2 01 and $0x1,%dl
ffffffff804bd607: 0 0f 85 16 04 00 00 jne ffffffff804bda23 <tcp_recvmsg+0x5b5>
ffffffff804bd60d: 0 83 7c 24 3c 00 cmpl $0x0,0x3c(%rsp)
ffffffff804bd612: 0 75 11 jne ffffffff804bd625 <tcp_recvmsg+0x1b7>
ffffffff804bd614: 0 be 53 05 00 00 mov $0x553,%esi
ffffffff804bd619: 0 48 c7 c7 13 d9 6a 80 mov $0xffffffff806ad913,%rdi
ffffffff804bd620: 0 e8 90 8b d7 ff callq ffffffff802361b5 <warn_on_slowpath>
ffffffff804bd625: 0 48 8b 6d 00 mov 0x0(%rbp),%rbp
ffffffff804bd629: 0 48 3b 6c 24 28 cmp 0x28(%rsp),%rbp
ffffffff804bd62e: 0 75 85 jne ffffffff804bd5b5 <tcp_recvmsg+0x147>
ffffffff804bd630: 80 44 3b 7c 24 4c cmp 0x4c(%rsp),%r15d
ffffffff804bd635: 4164 7c 0b jl ffffffff804bd642 <tcp_recvmsg+0x1d4>
ffffffff804bd637: 0 48 83 7b 68 00 cmpq $0x0,0x68(%rbx)
ffffffff804bd63c: 0 0f 84 07 04 00 00 je ffffffff804bda49 <tcp_recvmsg+0x5db>
ffffffff804bd642: 1 45 85 ff test %r15d,%r15d
ffffffff804bd645: 3438 74 49 je ffffffff804bd690 <tcp_recvmsg+0x222>
ffffffff804bd647: 0 83 bb 44 01 00 00 00 cmpl $0x0,0x144(%rbx)
ffffffff804bd64e: 0 0f 85 f5 03 00 00 jne ffffffff804bda49 <tcp_recvmsg+0x5db>
ffffffff804bd654: 0 8a 43 02 mov 0x2(%rbx),%al
ffffffff804bd657: 0 3c 07 cmp $0x7,%al
ffffffff804bd659: 0 0f 84 ea 03 00 00 je ffffffff804bda49 <tcp_recvmsg+0x5db>
ffffffff804bd65f: 0 f6 43 38 01 testb $0x1,0x38(%rbx)
ffffffff804bd663: 0 0f 85 e0 03 00 00 jne ffffffff804bda49 <tcp_recvmsg+0x5db>
ffffffff804bd669: 0 48 83 7c 24 58 00 cmpq $0x0,0x58(%rsp)
ffffffff804bd66f: 0 0f 84 d4 03 00 00 je ffffffff804bda49 <tcp_recvmsg+0x5db>
ffffffff804bd675: 0 65 48 8b 3c 25 00 00 mov %gs:0x0,%rdi
ffffffff804bd67c: 0 00 00
ffffffff804bd67e: 0 e8 3a e0 ff ff callq ffffffff804bb6bd <signal_pending>
ffffffff804bd683: 0 85 c0 test %eax,%eax
ffffffff804bd685: 0 0f 84 ac 00 00 00 je ffffffff804bd737 <tcp_recvmsg+0x2c9>
ffffffff804bd68b: 0 e9 b9 03 00 00 jmpq ffffffff804bda49 <tcp_recvmsg+0x5db>
ffffffff804bd690: 0 be 01 00 00 00 mov $0x1,%esi
ffffffff804bd695: 4166 48 89 df mov %rbx,%rdi
ffffffff804bd698: 0 e8 7b de ff ff callq ffffffff804bb518 <sock_flag>
ffffffff804bd69d: 0 85 c0 test %eax,%eax
ffffffff804bd69f: 276 0f 85 a4 03 00 00 jne ffffffff804bda49 <tcp_recvmsg+0x5db>
ffffffff804bd6a5: 126 83 bb 44 01 00 00 00 cmpl $0x0,0x144(%rbx)
ffffffff804bd6ac: 0 74 10 je ffffffff804bd6be <tcp_recvmsg+0x250>
ffffffff804bd6ae: 0 48 89 df mov %rbx,%rdi
ffffffff804bd6b1: 0 e8 00 df ff ff callq ffffffff804bb5b6 <sock_error>
ffffffff804bd6b6: 0 41 89 c7 mov %eax,%r15d
ffffffff804bd6b9: 0 e9 8b 03 00 00 jmpq ffffffff804bda49 <tcp_recvmsg+0x5db>
ffffffff804bd6be: 112 f6 43 38 01 testb $0x1,0x38(%rbx)
ffffffff804bd6c2: 3451 0f 85 81 03 00 00 jne ffffffff804bda49 <tcp_recvmsg+0x5db>
ffffffff804bd6c8: 497 8a 43 02 mov 0x2(%rbx),%al
ffffffff804bd6cb: 0 3c 07 cmp $0x7,%al
ffffffff804bd6cd: 113 75 20 jne ffffffff804bd6ef <tcp_recvmsg+0x281>
ffffffff804bd6cf: 0 be 01 00 00 00 mov $0x1,%esi
ffffffff804bd6d4: 0 48 89 df mov %rbx,%rdi
ffffffff804bd6d7: 0 e8 3c de ff ff callq ffffffff804bb518 <sock_flag>
ffffffff804bd6dc: 0 85 c0 test %eax,%eax
ffffffff804bd6de: 0 0f 85 65 03 00 00 jne ffffffff804bda49 <tcp_recvmsg+0x5db>
ffffffff804bd6e4: 0 41 bf 95 ff ff ff mov $0xffffff95,%r15d
ffffffff804bd6ea: 0 e9 5a 03 00 00 jmpq ffffffff804bda49 <tcp_recvmsg+0x5db>
ffffffff804bd6ef: 118 48 83 7c 24 58 00 cmpq $0x0,0x58(%rsp)
ffffffff804bd6f5: 398 75 0b jne ffffffff804bd702 <tcp_recvmsg+0x294>
ffffffff804bd6f7: 0 41 bf f5 ff ff ff mov $0xfffffff5,%r15d
ffffffff804bd6fd: 0 e9 47 03 00 00 jmpq ffffffff804bda49 <tcp_recvmsg+0x5db>
ffffffff804bd702: 0 65 48 8b 3c 25 00 00 mov %gs:0x0,%rdi
ffffffff804bd709: 0 00 00
ffffffff804bd70b: 2993 e8 ad df ff ff callq ffffffff804bb6bd <signal_pending>
ffffffff804bd710: 200 85 c0 test %eax,%eax
ffffffff804bd712: 0 74 23 je ffffffff804bd737 <tcp_recvmsg+0x2c9>
ffffffff804bd714: 0 48 b8 ff ff ff ff ff mov $0x7fffffffffffffff,%rax
ffffffff804bd71b: 0 ff ff 7f
ffffffff804bd71e: 0 48 39 44 24 58 cmp %rax,0x58(%rsp)
ffffffff804bd723: 0 41 bf 00 fe ff ff mov $0xfffffe00,%r15d
ffffffff804bd729: 0 b8 fc ff ff ff mov $0xfffffffc,%eax
ffffffff804bd72e: 0 44 0f 45 f8 cmovne %eax,%r15d
ffffffff804bd732: 0 e9 12 03 00 00 jmpq ffffffff804bda49 <tcp_recvmsg+0x5db>
ffffffff804bd737: 207 44 89 fe mov %r15d,%esi
ffffffff804bd73a: 198 48 89 df mov %rbx,%rdi
ffffffff804bd73d: 0 e8 cc e9 ff ff callq ffffffff804bc10e <tcp_cleanup_rbuf>
ffffffff804bd742: 227 83 3d 9b ad 3f 00 00 cmpl $0x0,0x3fad9b(%rip) # ffffffff808b84e4 <sysctl_tcp_low_latency>
ffffffff804bd749: 210 0f 85 81 00 00 00 jne ffffffff804bd7d0 <tcp_recvmsg+0x362>
ffffffff804bd74f: 0 48 8b ab 28 04 00 00 mov 0x428(%rbx),%rbp
ffffffff804bd756: 0 48 3b 6c 24 50 cmp 0x50(%rsp),%rbp
ffffffff804bd75b: 232 75 73 jne ffffffff804bd7d0 <tcp_recvmsg+0x362>
ffffffff804bd75d: 0 48 83 7c 24 50 00 cmpq $0x0,0x50(%rsp)
ffffffff804bd763: 7 75 27 jne ffffffff804bd78c <tcp_recvmsg+0x31e>
ffffffff804bd765: 229 83 7c 24 1c 00 cmpl $0x0,0x1c(%rsp)
ffffffff804bd76a: 30 75 20 jne ffffffff804bd78c <tcp_recvmsg+0x31e>
ffffffff804bd76c: 7 48 8b 54 24 30 mov 0x30(%rsp),%rdx
ffffffff804bd771: 191 65 48 8b 2c 25 00 00 mov %gs:0x0,%rbp
ffffffff804bd778: 0 00 00
ffffffff804bd77a: 12 48 89 ab 28 04 00 00 mov %rbp,0x428(%rbx)
ffffffff804bd781: 2617 48 8b 42 10 mov 0x10(%rdx),%rax
ffffffff804bd785: 670 48 89 83 30 04 00 00 mov %rax,0x430(%rbx)
ffffffff804bd78c: 11 8b 83 f4 03 00 00 mov 0x3f4(%rbx),%eax
ffffffff804bd792: 188 3b 83 f0 03 00 00 cmp 0x3f0(%rbx),%eax
ffffffff804bd798: 166 44 89 b3 3c 04 00 00 mov %r14d,0x43c(%rbx)
ffffffff804bd79f: 5 74 18 je ffffffff804bd7b9 <tcp_recvmsg+0x34b>
ffffffff804bd7a1: 0 83 7c 24 1c 00 cmpl $0x0,0x1c(%rsp)
ffffffff804bd7a6: 0 75 11 jne ffffffff804bd7b9 <tcp_recvmsg+0x34b>
ffffffff804bd7a8: 0 be 92 05 00 00 mov $0x592,%esi
ffffffff804bd7ad: 0 48 c7 c7 13 d9 6a 80 mov $0xffffffff806ad913,%rdi
ffffffff804bd7b4: 0 e8 fc 89 d7 ff callq ffffffff802361b5 <warn_on_slowpath>
ffffffff804bd7b9: 336 48 8b 4c 24 20 mov 0x20(%rsp),%rcx
ffffffff804bd7be: 302 48 39 8b 10 04 00 00 cmp %rcx,0x410(%rbx)
ffffffff804bd7c5: 1176 48 89 6c 24 50 mov %rbp,0x50(%rsp)
ffffffff804bd7ca: 244 0f 85 81 00 00 00 jne ffffffff804bd851 <tcp_recvmsg+0x3e3>
ffffffff804bd7d0: 135 44 3b 7c 24 4c cmp 0x4c(%rsp),%r15d
ffffffff804bd7d5: 112 7c 12 jl ffffffff804bd7e9 <tcp_recvmsg+0x37b>
ffffffff804bd7d7: 0 48 89 df mov %rbx,%rdi
ffffffff804bd7da: 0 e8 57 7f fc ff callq ffffffff80485736 <release_sock>
ffffffff804bd7df: 0 48 89 df mov %rbx,%rdi
ffffffff804bd7e2: 0 e8 96 e5 ff ff callq ffffffff804bbd7d <lock_sock>
ffffffff804bd7e7: 0 eb 0d jmp ffffffff804bd7f6 <tcp_recvmsg+0x388>
ffffffff804bd7e9: 152 48 8d 74 24 58 lea 0x58(%rsp),%rsi
ffffffff804bd7ee: 563 48 89 df mov %rbx,%rdi
ffffffff804bd7f1: 59 e8 83 99 fc ff callq ffffffff80487179 <sk_wait_data>
ffffffff804bd7f6: 86 48 83 7c 24 50 00 cmpq $0x0,0x50(%rsp)
ffffffff804bd7fc: 8550 0f 84 8a 00 00 00 je ffffffff804bd88c <tcp_recvmsg+0x41e>
ffffffff804bd802: 4038 44 89 f1 mov %r14d,%ecx
ffffffff804bd805: 900 2b 8b 3c 04 00 00 sub 0x43c(%rbx),%ecx
ffffffff804bd80b: 5 74 28 je ffffffff804bd835 <tcp_recvmsg+0x3c7>
ffffffff804bd80d: 0 48 8b 05 ac 3e 5f 00 mov 0x5f3eac(%rip),%rax # ffffffff80ab16c0 <init_net+0xf0>
ffffffff804bd814: 1 41 01 cf add %ecx,%r15d
ffffffff804bd817: 0 65 8b 14 25 24 00 00 mov %gs:0x24,%edx
ffffffff804bd81e: 0 00
ffffffff804bd81f: 0 89 d2 mov %edx,%edx
ffffffff804bd821: 0 48 f7 d0 not %rax
ffffffff804bd824: 0 48 8b 04 d0 mov (%rax,%rdx,8),%rax
ffffffff804bd828: 0 48 63 d1 movslq %ecx,%rdx
ffffffff804bd82b: 0 49 29 d6 sub %rdx,%r14
ffffffff804bd82e: 0 48 01 90 b8 00 00 00 add %rdx,0xb8(%rax)
ffffffff804bd835: 4 8b 83 f0 03 00 00 mov 0x3f0(%rbx),%eax
ffffffff804bd83b: 373 3b 83 f4 03 00 00 cmp 0x3f4(%rbx),%eax
ffffffff804bd841: 3604 75 49 jne ffffffff804bd88c <tcp_recvmsg+0x41e>
ffffffff804bd843: 0 48 8b 44 24 20 mov 0x20(%rsp),%rax
ffffffff804bd848: 971 48 39 83 10 04 00 00 cmp %rax,0x410(%rbx)
ffffffff804bd84f: 11 74 3b je ffffffff804bd88c <tcp_recvmsg+0x41e>
ffffffff804bd851: 6 48 89 df mov %rbx,%rdi
ffffffff804bd854: 267 e8 94 e6 ff ff callq ffffffff804bbeed <tcp_prequeue_process>
ffffffff804bd859: 0 44 89 f1 mov %r14d,%ecx
ffffffff804bd85c: 879 2b 8b 3c 04 00 00 sub 0x43c(%rbx),%ecx
ffffffff804bd862: 256 74 28 je ffffffff804bd88c <tcp_recvmsg+0x41e>
ffffffff804bd864: 0 48 8b 05 55 3e 5f 00 mov 0x5f3e55(%rip),%rax # ffffffff80ab16c0 <init_net+0xf0>
ffffffff804bd86b: 116 41 01 cf add %ecx,%r15d
ffffffff804bd86e: 17 65 8b 14 25 24 00 00 mov %gs:0x24,%edx
ffffffff804bd875: 0 00
ffffffff804bd876: 0 89 d2 mov %edx,%edx
ffffffff804bd878: 1 48 f7 d0 not %rax
ffffffff804bd87b: 5 48 8b 04 d0 mov (%rax,%rdx,8),%rax
ffffffff804bd87f: 0 48 63 d1 movslq %ecx,%rdx
ffffffff804bd882: 6 49 29 d6 sub %rdx,%r14
ffffffff804bd885: 7 48 01 90 c0 00 00 00 add %rdx,0xc0(%rax)
ffffffff804bd88c: 11 83 7c 24 3c 00 cmpl $0x0,0x3c(%rsp)
ffffffff804bd891: 438 0f 84 a9 01 00 00 je ffffffff804bda40 <tcp_recvmsg+0x5d2>
ffffffff804bd897: 0 8b 44 24 60 mov 0x60(%rsp),%eax
ffffffff804bd89b: 0 3b 83 f4 03 00 00 cmp 0x3f4(%rbx),%eax
ffffffff804bd8a1: 0 0f 84 99 01 00 00 je ffffffff804bda40 <tcp_recvmsg+0x5d2>
ffffffff804bd8a7: 0 e8 19 ad fd ff callq ffffffff804985c5 <net_ratelimit>
ffffffff804bd8ac: 0 85 c0 test %eax,%eax
ffffffff804bd8ae: 0 74 24 je ffffffff804bd8d4 <tcp_recvmsg+0x466>
ffffffff804bd8b0: 0 65 48 8b 34 25 00 00 mov %gs:0x0,%rsi
ffffffff804bd8b7: 0 00 00
ffffffff804bd8b9: 0 8b 96 70 01 00 00 mov 0x170(%rsi),%edx
ffffffff804bd8bf: 0 48 c7 c7 6a d9 6a 80 mov $0xffffffff806ad96a,%rdi
ffffffff804bd8c6: 0 48 81 c6 68 03 00 00 add $0x368,%rsi
ffffffff804bd8cd: 0 31 c0 xor %eax,%eax
ffffffff804bd8cf: 0 e8 a0 94 d7 ff callq ffffffff80236d74 <printk>
ffffffff804bd8d4: 0 8b 83 f4 03 00 00 mov 0x3f4(%rbx),%eax
ffffffff804bd8da: 0 89 44 24 60 mov %eax,0x60(%rsp)
ffffffff804bd8de: 0 e9 5d 01 00 00 jmpq ffffffff804bda40 <tcp_recvmsg+0x5d2>
ffffffff804bd8e3: 4077 44 29 e8 sub %r13d,%eax
ffffffff804bd8e6: 6031 4d 89 f4 mov %r14,%r12
ffffffff804bd8e9: 0 4c 39 f0 cmp %r14,%rax
ffffffff804bd8ec: 0 4c 0f 46 e0 cmovbe %rax,%r12
ffffffff804bd8f0: 934 66 83 bb 7c 04 00 00 cmpw $0x0,0x47c(%rbx)
ffffffff804bd8f7: 0 00
ffffffff804bd8f8: 0 74 38 je ffffffff804bd932 <tcp_recvmsg+0x4c4>
ffffffff804bd8fa: 0 8b 83 84 05 00 00 mov 0x584(%rbx),%eax
ffffffff804bd900: 0 29 f0 sub %esi,%eax
ffffffff804bd902: 0 89 c2 mov %eax,%edx
ffffffff804bd904: 0 4c 39 e2 cmp %r12,%rdx
ffffffff804bd907: 0 73 29 jae ffffffff804bd932 <tcp_recvmsg+0x4c4>
ffffffff804bd909: 0 85 c0 test %eax,%eax
ffffffff804bd90b: 0 74 05 je ffffffff804bd912 <tcp_recvmsg+0x4a4>
ffffffff804bd90d: 0 49 89 d4 mov %rdx,%r12
ffffffff804bd910: 0 eb 20 jmp ffffffff804bd932 <tcp_recvmsg+0x4c4>
ffffffff804bd912: 0 be 02 00 00 00 mov $0x2,%esi
ffffffff804bd917: 0 48 89 df mov %rbx,%rdi
ffffffff804bd91a: 0 e8 f9 db ff ff callq ffffffff804bb518 <sock_flag>
ffffffff804bd91f: 0 85 c0 test %eax,%eax
ffffffff804bd921: 0 75 0f jne ffffffff804bd932 <tcp_recvmsg+0x4c4>
ffffffff804bd923: 0 48 8b 54 24 40 mov 0x40(%rsp),%rdx
ffffffff804bd928: 0 41 ff c5 inc %r13d
ffffffff804bd92b: 0 ff 02 incl (%rdx)
ffffffff804bd92d: 0 49 ff cc dec %r12
ffffffff804bd930: 0 74 4c je ffffffff804bd97e <tcp_recvmsg+0x510>
ffffffff804bd932: 906 83 7c 24 0c 00 cmpl $0x0,0xc(%rsp)
ffffffff804bd937: 6039 75 2f jne ffffffff804bd968 <tcp_recvmsg+0x4fa>
ffffffff804bd939: 48 48 8b 4c 24 30 mov 0x30(%rsp),%rcx
ffffffff804bd93e: 1412 44 89 ee mov %r13d,%esi
ffffffff804bd941: 6648 48 89 ef mov %rbp,%rdi
ffffffff804bd944: 0 48 8b 51 10 mov 0x10(%rcx),%rdx
ffffffff804bd948: 1524 44 89 e1 mov %r12d,%ecx
ffffffff804bd94b: 167 e8 c5 d3 fc ff callq ffffffff8048ad15 <skb_copy_datagram_iovec>
ffffffff804bd950: 0 85 c0 test %eax,%eax
ffffffff804bd952: 1038 74 14 je ffffffff804bd968 <tcp_recvmsg+0x4fa>
ffffffff804bd954: 0 45 85 ff test %r15d,%r15d
ffffffff804bd957: 0 0f 85 ec 00 00 00 jne ffffffff804bda49 <tcp_recvmsg+0x5db>
ffffffff804bd95d: 0 41 bf f2 ff ff ff mov $0xfffffff2,%r15d
ffffffff804bd963: 0 e9 e1 00 00 00 jmpq ffffffff804bda49 <tcp_recvmsg+0x5db>
ffffffff804bd968: 28 48 8b 54 24 40 mov 0x40(%rsp),%rdx
ffffffff804bd96d: 5713 48 89 df mov %rbx,%rdi
ffffffff804bd970: 241 45 01 e7 add %r12d,%r15d
ffffffff804bd973: 27 4d 29 e6 sub %r12,%r14
ffffffff804bd976: 626 44 01 22 add %r12d,(%rdx)
ffffffff804bd979: 221 e8 fe 11 00 00 callq ffffffff804beb7c <tcp_rcv_space_adjust>
ffffffff804bd97e: 1425 66 83 bb 7c 04 00 00 cmpw $0x0,0x47c(%rbx)
ffffffff804bd985: 0 00
ffffffff804bd986: 3430 74 63 je ffffffff804bd9eb <tcp_recvmsg+0x57d>
ffffffff804bd988: 0 8b 8b f4 03 00 00 mov 0x3f4(%rbx),%ecx
ffffffff804bd98e: 0 39 8b 84 05 00 00 cmp %ecx,0x584(%rbx)
ffffffff804bd994: 0 79 55 jns ffffffff804bd9eb <tcp_recvmsg+0x57d>
ffffffff804bd996: 0 48 8b 44 24 10 mov 0x10(%rsp),%rax
ffffffff804bd99b: 0 48 39 83 f8 04 00 00 cmp %rax,0x4f8(%rbx)
ffffffff804bd9a2: 0 66 c7 83 7c 04 00 00 movw $0x0,0x47c(%rbx)
ffffffff804bd9a9: 0 00 00
ffffffff804bd9ab: 0 75 3e jne ffffffff804bd9eb <tcp_recvmsg+0x57d>
ffffffff804bd9ad: 0 83 bb c0 04 00 00 00 cmpl $0x0,0x4c0(%rbx)
ffffffff804bd9b4: 0 74 35 je ffffffff804bd9eb <tcp_recvmsg+0x57d>
ffffffff804bd9b6: 0 8b 83 94 00 00 00 mov 0x94(%rbx),%eax
ffffffff804bd9bc: 0 3b 43 3c cmp 0x3c(%rbx),%eax
ffffffff804bd9bf: 0 7d 2a jge ffffffff804bd9eb <tcp_recvmsg+0x57d>
ffffffff804bd9c1: 0 0f b7 83 e8 03 00 00 movzwl 0x3e8(%rbx),%eax
ffffffff804bd9c8: 0 8a 8b 9d 04 00 00 mov 0x49d(%rbx),%cl
ffffffff804bd9ce: 0 8b 93 44 04 00 00 mov 0x444(%rbx),%edx
ffffffff804bd9d4: 0 83 e1 0f and $0xf,%ecx
ffffffff804bd9d7: 0 c1 e0 1a shl $0x1a,%eax
ffffffff804bd9da: 0 d3 ea shr %cl,%edx
ffffffff804bd9dc: 0 09 d0 or %edx,%eax
ffffffff804bd9de: 0 0d 00 00 10 00 or $0x100000,%eax
ffffffff804bd9e3: 0 0f c8 bswap %eax
ffffffff804bd9e5: 0 89 83 ec 03 00 00 mov %eax,0x3ec(%rbx)
ffffffff804bd9eb: 0 8b 55 68 mov 0x68(%rbp),%edx
ffffffff804bd9ee: 1655 44 89 e8 mov %r13d,%eax
ffffffff804bd9f1: 32 4c 01 e0 add %r12,%rax
ffffffff804bd9f4: 0 48 39 d0 cmp %rdx,%rax
ffffffff804bd9f7: 847 72 47 jb ffffffff804bda40 <tcp_recvmsg+0x5d2>
ffffffff804bd9f9: 0 8b 95 b8 00 00 00 mov 0xb8(%rbp),%edx
ffffffff804bd9ff: 80 48 8b 85 d0 00 00 00 mov 0xd0(%rbp),%rax
ffffffff804bda06: 441 f6 44 02 0d 01 testb $0x1,0xd(%rdx,%rax,1)
ffffffff804bda0b: 0 75 16 jne ffffffff804bda23 <tcp_recvmsg+0x5b5>
ffffffff804bda0d: 0 83 7c 24 3c 00 cmpl $0x0,0x3c(%rsp)
ffffffff804bda12: 453 75 2c jne ffffffff804bda40 <tcp_recvmsg+0x5d2>
ffffffff804bda14: 0 31 d2 xor %edx,%edx
ffffffff804bda16: 0 48 89 ee mov %rbp,%rsi
ffffffff804bda19: 477 48 89 df mov %rbx,%rdi
ffffffff804bda1c: 0 e8 0f e4 ff ff callq ffffffff804bbe30 <sk_eat_skb>
ffffffff804bda21: 562 eb 1d jmp ffffffff804bda40 <tcp_recvmsg+0x5d2>
ffffffff804bda23: 0 48 8b 54 24 40 mov 0x40(%rsp),%rdx
ffffffff804bda28: 0 ff 02 incl (%rdx)
ffffffff804bda2a: 0 83 7c 24 3c 00 cmpl $0x0,0x3c(%rsp)
ffffffff804bda2f: 0 75 18 jne ffffffff804bda49 <tcp_recvmsg+0x5db>
ffffffff804bda31: 0 31 d2 xor %edx,%edx
ffffffff804bda33: 0 48 89 ee mov %rbp,%rsi
ffffffff804bda36: 0 48 89 df mov %rbx,%rdi
ffffffff804bda39: 0 e8 f2 e3 ff ff callq ffffffff804bbe30 <sk_eat_skb>
ffffffff804bda3e: 0 eb 09 jmp ffffffff804bda49 <tcp_recvmsg+0x5db>
ffffffff804bda40: 959 4d 85 f6 test %r14,%r14
ffffffff804bda43: 4766 0f 85 f8 fa ff ff jne ffffffff804bd541 <tcp_recvmsg+0xd3>
ffffffff804bda49: 217 48 83 7c 24 50 00 cmpq $0x0,0x50(%rsp)
ffffffff804bda4f: 2084 74 71 je ffffffff804bdac2 <tcp_recvmsg+0x654>
ffffffff804bda51: 40 48 8d 83 10 04 00 00 lea 0x410(%rbx),%rax
ffffffff804bda58: 448 48 39 83 10 04 00 00 cmp %rax,0x410(%rbx)
ffffffff804bda5f: 4 74 4c je ffffffff804bdaad <tcp_recvmsg+0x63f>
ffffffff804bda61: 0 31 c0 xor %eax,%eax
ffffffff804bda63: 0 45 85 ff test %r15d,%r15d
ffffffff804bda66: 0 48 89 df mov %rbx,%rdi
ffffffff804bda69: 0 41 0f 4f c6 cmovg %r14d,%eax
ffffffff804bda6d: 0 89 83 3c 04 00 00 mov %eax,0x43c(%rbx)
ffffffff804bda73: 0 e8 75 e4 ff ff callq ffffffff804bbeed <tcp_prequeue_process>
ffffffff804bda78: 0 45 85 ff test %r15d,%r15d
ffffffff804bda7b: 0 7e 30 jle ffffffff804bdaad <tcp_recvmsg+0x63f>
ffffffff804bda7d: 0 44 89 f1 mov %r14d,%ecx
ffffffff804bda80: 0 2b 8b 3c 04 00 00 sub 0x43c(%rbx),%ecx
ffffffff804bda86: 0 74 25 je ffffffff804bdaad <tcp_recvmsg+0x63f>
ffffffff804bda88: 0 48 8b 05 31 3c 5f 00 mov 0x5f3c31(%rip),%rax # ffffffff80ab16c0 <init_net+0xf0>
ffffffff804bda8f: 0 41 01 cf add %ecx,%r15d
ffffffff804bda92: 0 65 8b 14 25 24 00 00 mov %gs:0x24,%edx
ffffffff804bda99: 0 00
ffffffff804bda9a: 0 89 d2 mov %edx,%edx
ffffffff804bda9c: 0 48 f7 d0 not %rax
ffffffff804bda9f: 0 48 8b 14 d0 mov (%rax,%rdx,8),%rdx
ffffffff804bdaa3: 0 48 63 c1 movslq %ecx,%rax
ffffffff804bdaa6: 0 48 01 82 c0 00 00 00 add %rax,0xc0(%rdx)
ffffffff804bdaad: 214 48 c7 83 28 04 00 00 movq $0x0,0x428(%rbx)
ffffffff804bdab4: 0 00 00 00 00
ffffffff804bdab8: 1530 c7 83 3c 04 00 00 00 movl $0x0,0x43c(%rbx)
ffffffff804bdabf: 0 00 00 00
ffffffff804bdac2: 1135 48 89 df mov %rbx,%rdi
ffffffff804bdac5: 3909 44 89 fe mov %r15d,%esi
ffffffff804bdac8: 0 e8 41 e6 ff ff callq ffffffff804bc10e <tcp_cleanup_rbuf>
ffffffff804bdacd: 1724 48 89 df mov %rbx,%rdi
ffffffff804bdad0: 932 e8 61 7c fc ff callq ffffffff80485736 <release_sock>
ffffffff804bdad5: 4661 e9 12 01 00 00 jmpq ffffffff804bdbec <tcp_recvmsg+0x77e>
ffffffff804bdada: 0 41 bc 95 ff ff ff mov $0xffffff95,%r12d
ffffffff804bdae0: 0 48 89 df mov %rbx,%rdi
ffffffff804bdae3: 0 45 89 e7 mov %r12d,%r15d
ffffffff804bdae6: 0 e8 4b 7c fc ff callq ffffffff80485736 <release_sock>
ffffffff804bdaeb: 0 e9 fc 00 00 00 jmpq ffffffff804bdbec <tcp_recvmsg+0x77e>
ffffffff804bdaf0: 0 be 02 00 00 00 mov $0x2,%esi
ffffffff804bdaf5: 0 48 89 df mov %rbx,%rdi
ffffffff804bdaf8: 0 e8 1b da ff ff callq ffffffff804bb518 <sock_flag>
ffffffff804bdafd: 0 85 c0 test %eax,%eax
ffffffff804bdaff: 0 0f 85 d4 00 00 00 jne ffffffff804bdbd9 <tcp_recvmsg+0x76b>
ffffffff804bdb05: 0 8b 83 7c 04 00 00 mov 0x47c(%rbx),%eax
ffffffff804bdb0b: 0 66 85 c0 test %ax,%ax
ffffffff804bdb0e: 0 0f 84 c5 00 00 00 je ffffffff804bdbd9 <tcp_recvmsg+0x76b>
ffffffff804bdb14: 0 66 3d 00 04 cmp $0x400,%ax
ffffffff804bdb18: 0 0f 84 bb 00 00 00 je ffffffff804bdbd9 <tcp_recvmsg+0x76b>
ffffffff804bdb1e: 0 8a 43 02 mov 0x2(%rbx),%al
ffffffff804bdb21: 0 3c 07 cmp $0x7,%al
ffffffff804bdb23: 0 75 17 jne ffffffff804bdb3c <tcp_recvmsg+0x6ce>
ffffffff804bdb25: 0 be 01 00 00 00 mov $0x1,%esi
ffffffff804bdb2a: 0 48 89 df mov %rbx,%rdi
ffffffff804bdb2d: 0 41 bc 95 ff ff ff mov $0xffffff95,%r12d
ffffffff804bdb33: 0 e8 e0 d9 ff ff callq ffffffff804bb518 <sock_flag>
ffffffff804bdb38: 0 85 c0 test %eax,%eax
ffffffff804bdb3a: 0 74 a4 je ffffffff804bdae0 <tcp_recvmsg+0x672>
ffffffff804bdb3c: 0 8b 83 7c 04 00 00 mov 0x47c(%rbx),%eax
ffffffff804bdb42: 0 f6 c4 01 test $0x1,%ah
ffffffff804bdb45: 0 74 79 je ffffffff804bdbc0 <tcp_recvmsg+0x752>
ffffffff804bdb47: 0 40 f6 c5 02 test $0x2,%bpl
ffffffff804bdb4b: 0 88 44 24 67 mov %al,0x67(%rsp)
ffffffff804bdb4f: 0 75 09 jne ffffffff804bdb5a <tcp_recvmsg+0x6ec>
ffffffff804bdb51: 0 66 c7 83 7c 04 00 00 movw $0x400,0x47c(%rbx)
ffffffff804bdb58: 0 00 04
ffffffff804bdb5a: 0 48 8b 4c 24 30 mov 0x30(%rsp),%rcx
ffffffff804bdb5f: 0 45 89 f4 mov %r14d,%r12d
ffffffff804bdb62: 0 8b 51 30 mov 0x30(%rcx),%edx
ffffffff804bdb65: 0 89 d0 mov %edx,%eax
ffffffff804bdb67: 0 83 c8 01 or $0x1,%eax
ffffffff804bdb6a: 0 45 85 f6 test %r14d,%r14d
ffffffff804bdb6d: 0 89 41 30 mov %eax,0x30(%rcx)
ffffffff804bdb70: 0 7e 33 jle ffffffff804bdba5 <tcp_recvmsg+0x737>
ffffffff804bdb72: 0 40 80 e5 20 and $0x20,%bpl
ffffffff804bdb76: 0 41 bc 01 00 00 00 mov $0x1,%r12d
ffffffff804bdb7c: 0 0f 85 5e ff ff ff jne ffffffff804bdae0 <tcp_recvmsg+0x672>
ffffffff804bdb82: 0 48 8b 79 10 mov 0x10(%rcx),%rdi
ffffffff804bdb86: 0 48 8d 74 24 67 lea 0x67(%rsp),%rsi
ffffffff804bdb8b: 0 ba 01 00 00 00 mov $0x1,%edx
ffffffff804bdb90: 0 41 bc f2 ff ff ff mov $0xfffffff2,%r12d
ffffffff804bdb96: 0 e8 8a cb fc ff callq ffffffff8048a725 <memcpy_toiovec>
ffffffff804bdb9b: 0 85 c0 test %eax,%eax
ffffffff804bdb9d: 0 0f 85 3d ff ff ff jne ffffffff804bdae0 <tcp_recvmsg+0x672>
ffffffff804bdba3: 0 eb 10 jmp ffffffff804bdbb5 <tcp_recvmsg+0x747>
ffffffff804bdba5: 0 48 8b 44 24 30 mov 0x30(%rsp),%rax
ffffffff804bdbaa: 0 83 ca 21 or $0x21,%edx
ffffffff804bdbad: 0 89 50 30 mov %edx,0x30(%rax)
ffffffff804bdbb0: 0 e9 2b ff ff ff jmpq ffffffff804bdae0 <tcp_recvmsg+0x672>
ffffffff804bdbb5: 0 41 bc 01 00 00 00 mov $0x1,%r12d
ffffffff804bdbbb: 0 e9 20 ff ff ff jmpq ffffffff804bdae0 <tcp_recvmsg+0x672>
ffffffff804bdbc0: 0 8a 43 02 mov 0x2(%rbx),%al
ffffffff804bdbc3: 0 3c 07 cmp $0x7,%al
ffffffff804bdbc5: 0 74 1d je ffffffff804bdbe4 <tcp_recvmsg+0x776>
ffffffff804bdbc7: 0 f6 43 38 01 testb $0x1,0x38(%rbx)
ffffffff804bdbcb: 0 41 bc f5 ff ff ff mov $0xfffffff5,%r12d
ffffffff804bdbd1: 0 0f 84 09 ff ff ff je ffffffff804bdae0 <tcp_recvmsg+0x672>
ffffffff804bdbd7: 0 eb 0b jmp ffffffff804bdbe4 <tcp_recvmsg+0x776>
ffffffff804bdbd9: 0 41 bc ea ff ff ff mov $0xffffffea,%r12d
ffffffff804bdbdf: 0 e9 fc fe ff ff jmpq ffffffff804bdae0 <tcp_recvmsg+0x672>
ffffffff804bdbe4: 0 45 31 e4 xor %r12d,%r12d
ffffffff804bdbe7: 0 e9 f4 fe ff ff jmpq ffffffff804bdae0 <tcp_recvmsg+0x672>
ffffffff804bdbec: 1206 48 83 c4 68 add $0x68,%rsp
ffffffff804bdbf0: 498 44 89 f8 mov %r15d,%eax
ffffffff804bdbf3: 387 5b pop %rbx
ffffffff804bdbf4: 462 5d pop %rbp
ffffffff804bdbf5: 0 41 5c pop %r12
ffffffff804bdbf7: 485 41 5d pop %r13
ffffffff804bdbf9: 466 41 5e pop %r14
ffffffff804bdbfb: 0 41 5f pop %r15
ffffffff804bdbfd: 796 c3 retq

no real hotspots either - but a bit too fractured code sequence, so
this function's icache footprint is too probably double the size of
what it could be.

a bit of overhead (8%) leaks in from a callsite:

ffffffff804bd46e: 882 41 57 push %r15
ffffffff804bd470: 15507 48 89 f7 mov %rsi,%rdi

(this is used as a dynamic function pointer too so i'm just guessing
that the common callsite would be sock_common_recvmsg().)

perhaps this sequence, about 7% of the total overhead of this
function, warrants mention:

ffffffff804bd7e2: 0 e8 96 e5 ff ff callq ffffffff804bbd7d <lock_sock>
ffffffff804bd7e7: 0 eb 0d jmp ffffffff804bd7f6 <tcp_recvmsg+0x388>
ffffffff804bd7e9: 152 48 8d 74 24 58 lea 0x58(%rsp),%rsi
ffffffff804bd7ee: 563 48 89 df mov %rbx,%rdi
ffffffff804bd7f1: 59 e8 83 99 fc ff callq ffffffff80487179 <sk_wait_data>
ffffffff804bd7f6: 86 48 83 7c 24 50 00 cmpq $0x0,0x50(%rsp)
ffffffff804bd7fc: 8550 0f 84 8a 00 00 00 je ffffffff804bd88c <tcp_recvmsg+0x41e>
ffffffff804bd802: 4038 44 89 f1 mov %r14d,%ecx

that's most likely lock_sock[_nested]()'s overhead leaking over into
this function:

ffffffff804857cb: 9392 <lock_sock_nested>:
ffffffff804857cb: 9392 41 55 push %r13
ffffffff804857cd: 4112 41 54 push %r12
ffffffff804857cf: 2 55 push %rbp
ffffffff804857d0: 7 48 8d 6f 40 lea 0x40(%rdi),%rbp
ffffffff804857d4: 1515 53 push %rbx
ffffffff804857d5: 0 48 89 fb mov %rdi,%rbx
ffffffff804857d8: 4 48 89 ef mov %rbp,%rdi
ffffffff804857db: 1461 48 83 ec 38 sub $0x38,%rsp
ffffffff804857df: 8 e8 78 11 09 00 callq ffffffff8051695c <_spin_lock_bh>
ffffffff804857e4: 4827 83 7b 44 00 cmpl $0x0,0x44(%rbx)
ffffffff804857e8: 2937 74 6d je ffffffff80485857 <lock_sock_nested+0x8c>
ffffffff804857ea: 0 65 48 8b 14 25 00 00 mov %gs:0x0,%rdx
ffffffff804857f1: 0 00 00
ffffffff804857f3: 0 fc cld
ffffffff804857f4: 0 31 c0 xor %eax,%eax
ffffffff804857f6: 0 48 89 e7 mov %rsp,%rdi
ffffffff804857f9: 0 b9 0a 00 00 00 mov $0xa,%ecx
ffffffff804857fe: 0 f3 ab rep stos %eax,%es:(%rdi)
ffffffff80485800: 0 48 8d 44 24 18 lea 0x18(%rsp),%rax
ffffffff80485805: 0 4c 8d 63 48 lea 0x48(%rbx),%r12
ffffffff80485809: 0 48 89 54 24 08 mov %rdx,0x8(%rsp)
ffffffff8048580e: 0 48 c7 44 24 10 80 78 movq $0xffffffff80247880,0x10(%rsp)
ffffffff80485815: 0 24 80
ffffffff80485817: 0 48 89 44 24 18 mov %rax,0x18(%rsp)
ffffffff8048581c: 0 48 89 44 24 20 mov %rax,0x20(%rsp)
ffffffff80485821: 0 ba 02 00 00 00 mov $0x2,%edx
ffffffff80485826: 0 48 89 e6 mov %rsp,%rsi
ffffffff80485829: 0 4c 89 e7 mov %r12,%rdi
ffffffff8048582c: 0 e8 fd 20 dc ff callq ffffffff8024792e <prepare_to_wait_exclusive>
ffffffff80485831: 0 48 89 ef mov %rbp,%rdi
ffffffff80485834: 0 e8 18 11 09 00 callq ffffffff80516951 <_spin_unlock_bh>
ffffffff80485839: 0 e8 52 f9 08 00 callq ffffffff80515190 <schedule>
ffffffff8048583e: 0 48 89 ef mov %rbp,%rdi
ffffffff80485841: 0 e8 16 11 09 00 callq ffffffff8051695c <_spin_lock_bh>
ffffffff80485846: 0 83 7b 44 00 cmpl $0x0,0x44(%rbx)
ffffffff8048584a: 0 75 d5 jne ffffffff80485821 <lock_sock_nested+0x56>
ffffffff8048584c: 0 48 89 e6 mov %rsp,%rsi
ffffffff8048584f: 0 4c 89 e7 mov %r12,%rdi
ffffffff80485852: 0 e8 7a 20 dc ff callq ffffffff802478d1 <finish_wait>
ffffffff80485857: 88 c7 43 44 01 00 00 00 movl $0x1,0x44(%rbx)
ffffffff8048585e: 3431 fe 43 40 incb 0x40(%rbx)
ffffffff80485861: 1568 e8 00 4e db ff callq ffffffff8023a666 <local_bh_enable>
ffffffff80485866: 1548 48 83 c4 38 add $0x38,%rsp
ffffffff8048586a: 61 5b pop %rbx
ffffffff8048586b: 1568 5d pop %rbp
ffffffff8048586c: 36 41 5c pop %r12
ffffffff8048586e: 0 41 5d pop %r13
ffffffff80485870: 2753 c3 retq

which is:

1748 void lock_sock_nested(struct sock *sk, int subclass)
1749 {
1750 might_sleep();
1751 spin_lock_bh(&sk->sk_lock.slock);
1752 if (sk->sk_lock.owned)
1753 __lock_sock(sk);
1754 sk->sk_lock.owned = 1;
1755 spin_unlock(&sk->sk_lock.slock);

that branch in the middle should perhaps be:

if (unlikely(sk->sk_lock.owned))

to make this function fall-through.

Ingo


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