• Steven Rostedt's avatar
    ftrace: Fix regression of :mod:module function enabling · 43dd61c9
    Steven Rostedt authored
    
    
    The new code that allows different utilities to pick and choose
    what functions they trace broke the :mod: hook that allows users
    to trace only functions of a particular module.
    
    The reason is that the :mod: hook bypasses the hash that is setup
    to allow individual users to trace their own functions and uses
    the global hash directly. But if the global hash has not been
    set up, it will cause a bug:
    
    echo '*:mod:radeon' > /sys/kernel/debug/set_ftrace_filter
    
    produces:
    
     [drm:drm_mode_getfb] *ERROR* invalid framebuffer id
     [drm:radeon_crtc_page_flip] *ERROR* failed to reserve new rbo buffer before flip
     BUG: unable to handle kernel paging request at ffffffff8160ec90
     IP: [<ffffffff810d9136>] add_hash_entry+0x66/0xd0
     PGD 1a05067 PUD 1a09063 PMD 80000000016001e1
     Oops: 0003 [#1] SMP Jul  7 04:02:28 phyllis kernel: [55303.858604] CPU 1
     Modules linked in: cryptd aes_x86_64 aes_generic binfmt_misc rfcomm bnep ip6table_filter hid radeon r8169 ahci libahci mii ttm drm_kms_helper drm video i2c_algo_bit intel_agp intel_gtt
    
     Pid: 10344, comm: bash Tainted: G        WC  3.0.0-rc5 #1 Dell Inc. Inspiron N5010/0YXXJJ
     RIP: 0010:[<ffffffff810d9136>]  [<ffffffff810d9136>] add_hash_entry+0x66/0xd0
     RSP: 0018:ffff88003a96bda8  EFLAGS: 00010246
     RAX: ffff8801301735c0 RBX: ffffffff8160ec80 RCX: 0000000000306ee0
     RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff880137c92940
     RBP: ffff88003a96bdb8 R08: ffff880137c95680 R09: 0000000000000000
     R10: 0000000000000001 R11: 0000000000000000 R12: ffffffff81c9df78
     R13: ffff8801153d1000 R14: 0000000000000000 R15: 0000000000000000
     FS: 00007f329c18a700(0000) GS:ffff880137c80000(0000) knlGS:0000000000000000
     CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
     CR2: ffffffff8160ec90 CR3: 000000003002b000 CR4: 00000000000006e0
     DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
     DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
     Process bash (pid: 10344, threadinfo ffff88003a96a000, task ffff88012fcfc470)
     Stack:
      0000000000000fd0 00000000000000fc ffff88003a96be38 ffffffff810d92f5
      ffff88011c4c4e00 ffff880000000000 000000000b69f4d0 ffffffff8160ec80
      ffff8800300e6f06 0000000081130295 0000000000000282 ffff8800300e6f00
     Call Trace:
      [<ffffffff810d92f5>] match_records+0x155/0x1b0
      [<ffffffff810d940c>] ftrace_mod_callback+0xbc/0x100
      [<ffffffff810dafdf>] ftrace_regex_write+0x16f/0x210
      [<ffffffff810db09f>] ftrace_filter_write+0xf/0x20
      [<ffffffff81166e48>] vfs_write+0xc8/0x190
      [<ffffffff81167001>] sys_write+0x51/0x90
      [<ffffffff815c7e02>] system_call_fastpath+0x16/0x1b
     Code: 48 8b 33 31 d2 48 85 f6 75 33 49 89 d4 4c 03 63 08 49 8b 14 24 48 85 d2 48 89 10 74 04 48 89 42 08 49 89 04 24 4c 89 60 08 31 d2
     RIP [<ffffffff810d9136>] add_hash_entry+0x66/0xd0
      RSP <ffff88003a96bda8>
     CR2: ffffffff8160ec90
     ---[ end trace a5d031828efdd88e ]---
    Reported-by: default avatarBrian Marete <marete@toshnix.com>
    Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
    43dd61c9
ftrace.c 87.8 KB