Skip to content

L
linux-davinci
An error occurred fetching the project authors.
Switch branch/tag
  1. 31 Mar, 2009 1 commit
  3. 30 Mar, 2009 1 commit
  5. 05 Mar, 2009 1 commit
  7. 04 Mar, 2009 2 commits
  9. 14 Feb, 2009 20 commits
  11. 04 Dec, 2008 1 commit
  13. 03 Dec, 2008 1 commit
  15. 25 Nov, 2008 1 commit
    • Ingo Molnar's avatar
      lockdep: fix unused function warning in kernel/lockdep.c · 7807fafa
      Ingo Molnar authored 
      Impact: fix build warning

this warning:

  kernel/lockdep.c:584: warning: ‘print_lock_dependencies’ defined but not used

triggers because print_lock_dependencies() is only used if both
CONFIG_TRACE_IRQFLAGS and CONFIG_PROVE_LOCKING are enabled.

But adding #ifdefs is not an option here - it would spread out to 4-5
other helper functions and uglify the file. So mark this function
as __used - it's static and the compiler can eliminate it just fine.
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      7807fafa
  17. 21 Nov, 2008 1 commit
  19. 28 Oct, 2008 2 commits
  21. 20 Oct, 2008 1 commit
  23. 27 Aug, 2008 1 commit
    • Zhu Yi's avatar
      lockdep: fix invalid list_del_rcu in zap_class · 74870172
      Zhu Yi authored 
      The problem is found during iwlagn driver testing on
v2.6.27-rc4-176-gb8e6c91c kernel, but it turns out to be a lockdep bug.
In our testing, we frequently load and unload the iwlagn driver
(>50 times). Then the MAX_STACK_TRACE_ENTRIES is reached (expected
behaviour?). The error message with the call trace is as below.

BUG: MAX_STACK_TRACE_ENTRIES too low!
turning off the locking correctness validator.
Pid: 4895, comm: iwlagn Not tainted 2.6.27-rc4 #13

Call Trace:
 [<ffffffff81014aa1>] save_stack_trace+0x22/0x3e
 [<ffffffff8105390a>] save_trace+0x8b/0x91
 [<ffffffff81054e60>] mark_lock+0x1b0/0x8fa
 [<ffffffff81056f71>] __lock_acquire+0x5b9/0x716
 [<ffffffffa00d818a>] ieee80211_sta_work+0x0/0x6ea [mac80211]
 [<ffffffff81057120>] lock_acquire+0x52/0x6b
 [<ffffffff81045f0e>] run_workqueue+0x97/0x1ed
 [<ffffffff81045f5e>] run_workqueue+0xe7/0x1ed
 [<ffffffff81045f0e>] run_workqueue+0x97/0x1ed
 [<ffffffff81046ae4>] worker_thread+0xd8/0xe3
 [<ffffffff81049503>] autoremove_wake_function+0x0/0x2e
 [<ffffffff81046a0c>] worker_thread+0x0/0xe3
 [<ffffffff810493ec>] kthread+0x47/0x73
 [<ffffffff8128e3ab>] trace_hardirqs_on_thunk+0x3a/0x3f
 [<ffffffff8100cea9>] child_rip+0xa/0x11
 [<ffffffff8100c4df>] restore_args+0x0/0x30
 [<ffffffff810316e1>] finish_task_switch+0x0/0xcc
 [<ffffffff810493a5>] kthread+0x0/0x73
 [<ffffffff8100ce9f>] child_rip+0x0/0x11

Although the above is harmless, when the ilwagn module is removed
later lockdep will trigger a kernel oops as below.

BUG: unable to handle kernel NULL pointer dereference at
0000000000000008
IP: [<ffffffff810531e1>] zap_class+0x24/0x82
PGD 73128067 PUD 7448c067 PMD 0
Oops: 0002 [1] SMP
CPU 0
Modules linked in: rfcomm l2cap bluetooth autofs4 sunrpc
nf_conntrack_ipv6 xt_state nf_conntrack xt_tcpudp ip6t_ipv6header
ip6t_REJECT ip6table_filter ip6_tables x_tables ipv6 cpufreq_ondemand
acpi_cpufreq dm_mirror dm_log dm_multipath dm_mod snd_hda_intel sr_mod
snd_seq_dummy snd_seq_oss snd_seq_midi_event battery snd_seq
snd_seq_device cdrom button snd_pcm_oss snd_mixer_oss snd_pcm
snd_timer snd_page_alloc e1000e snd_hwdep sg iTCO_wdt
iTCO_vendor_support ac pcspkr i2c_i801 i2c_core snd soundcore video
output ata_piix ata_generic libata sd_mod scsi_mod ext3 jbd mbcache
uhci_hcd ohci_hcd ehci_hcd [last unloaded: mac80211]
Pid: 4941, comm: modprobe Not tainted 2.6.27-rc4 #10
RIP: 0010:[<ffffffff810531e1>]  [<ffffffff810531e1>]
zap_class+0x24/0x82
RSP: 0000:ffff88007bcb3eb0  EFLAGS: 00010046
RAX: 0000000000068ee8 RBX: ffffffff8192a0a0 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000001dfb RDI: ffffffff816e70b0
RBP: ffffffffa00cd000 R08: ffffffff816818f8 R09: ffff88007c923558
R10: ffffe20002ad2408 R11: ffffffff811028ec R12: ffffffff8192a0a0
R13: 000000000002bd90 R14: 0000000000000000 R15: 0000000000000296
FS:  00007f9d1cee56f0(0000) GS:ffffffff814a58c0(0000)
knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: 0000000000000008 CR3: 0000000073047000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process modprobe (pid: 4941, threadinfo ffff88007bcb2000, task
ffff8800758d1fc0)
Stack:  ffffffff81057376 0000000000000000 ffffffffa00f7b00
0000000000000000
 0000000000000080 0000000000618278 00007fff24f16720 0000000000000000
 ffffffff8105d37a ffffffffa00f7b00 ffffffff8105d591 313132303863616d
Call Trace:
 [<ffffffff81057376>] ? lockdep_free_key_range+0x61/0xf5
 [<ffffffff8105d37a>] ? free_module+0xd4/0xe4
 [<ffffffff8105d591>] ? sys_delete_module+0x1de/0x1f9
 [<ffffffff8106dbfa>] ? audit_syscall_entry+0x12d/0x160
 [<ffffffff8100be2b>] ? system_call_fastpath+0x16/0x1b

Code: b2 00 01 00 00 00 c3 31 f6 49 c7 c0 10 8a 61 81 eb 32 49 39 38
75 26 48 98 48 6b c0 38 48 8b 90 08 8a 61 81 48 8b 88 00 8a 61 81 <48>
89 51 08 48 89 0a 48 c7 80 08 8a 61 81 00 02 20 00 48 ff c6
RIP  [<ffffffff810531e1>] zap_class+0x24/0x82
 RSP <ffff88007bcb3eb0>
CR2: 0000000000000008
---[ end trace a1297e0c4abb0f2e ]---

The root cause for this oops is in add_lock_to_list() when
save_trace() fails due to MAX_STACK_TRACE_ENTRIES is reached,
entry->class is assigned but entry is never added into any lock list.
This makes the list_del_rcu() in zap_class() oops later when the
module is unloaded. This patch fixes the problem by assigning
entry->class after save_trace() returns success.
Signed-off-by: default avatarZhu Yi <yi.zhu@intel.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      74870172
  25. 26 Aug, 2008 1 commit
  27. 18 Aug, 2008 1 commit
  29. 13 Aug, 2008 1 commit
  31. 11 Aug, 2008 4 commits
    • Peter Zijlstra's avatar
      lockdep: fix debug_lock_alloc · 0f2bc27b
      Peter Zijlstra authored 
      When we enable DEBUG_LOCK_ALLOC but do not enable PROVE_LOCKING and or
LOCK_STAT, lock_alloc() and lock_release() turn into nops, even though
we should be doing hlock checking (check=1).

This causes a false warning and a lockdep self-disable.

Rectify this.
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      0f2bc27b
    • Rabin Vincent's avatar
      lockdep: handle chains involving classes defined in modules · 8bfe0298
      Rabin Vincent authored 
      Solve this by marking the classes as unused and not printing information
about the unused classes.
Reported-by: default avatarEric Sesterhenn <snakebyte@gmx.de>
Signed-off-by: default avatarRabin Vincent <rabin@rab.in>
Acked-by: default avatarHuang Ying <ying.huang@intel.com>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      8bfe0298
    • Peter Zijlstra's avatar
      lockdep: lock protection locks · 7531e2f3
      Peter Zijlstra authored 
      On Fri, 2008-08-01 at 16:26 -0700, Linus Torvalds wrote:

> On Fri, 1 Aug 2008, David Miller wrote:
> >
> > Taking more than a few locks of the same class at once is bad
> > news and it's better to find an alternative method.
>
> It's not always wrong.
>
> If you can guarantee that anybody that takes more than one lock of a
> particular class will always take a single top-level lock _first_, then
> that's all good. You can obviously screw up and take the same lock _twice_
> (which will deadlock), but at least you cannot get into ABBA situations.
>
> So maybe the right thing to do is to just teach lockdep about "lock
> protection locks". That would have solved the multi-queue issues for
> networking too - all the actual network drivers would still have taken
> just their single queue lock, but the one case that needs to take all of
> them would have taken a separate top-level lock first.
>
> Never mind that the multi-queue locks were always taken in the same order:
> it's never wrong to just have some top-level serialization, and anybody
> who needs to take <n> locks might as well do <n+1>, because they sure as
> hell aren't going to be on _any_ fastpaths.
>
> So the simplest solution really sounds like just teaching lockdep about
> that one special case. It's not "nesting" exactly, although it's obviously
> related to it.

Do as Linus suggested. The lock protection lock is called nest_lock.

Note that we still have the MAX_LOCK_DEPTH (48) limit to consider, so anything
that spills that it still up shit creek.
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      7531e2f3
    • Dave Jones's avatar
      lockdep: shrink held_lock structure · f82b217e
      Dave Jones authored 
      struct held_lock {
        u64                        prev_chain_key;       /*     0     8 */
        struct lock_class *        class;                /*     8     8 */
        long unsigned int          acquire_ip;           /*    16     8 */
        struct lockdep_map *       instance;             /*    24     8 */
        int                        irq_context;          /*    32     4 */
        int                        trylock;              /*    36     4 */
        int                        read;                 /*    40     4 */
        int                        check;                /*    44     4 */
        int                        hardirqs_off;         /*    48     4 */

        /* size: 56, cachelines: 1 */
        /* padding: 4 */
        /* last cacheline: 56 bytes */
};

struct held_lock {
        u64                        prev_chain_key;       /*     0     8 */
        long unsigned int          acquire_ip;           /*     8     8 */
        struct lockdep_map *       instance;             /*    16     8 */
        unsigned int               class_idx:11;         /*    24:21  4 */
        unsigned int               irq_context:2;        /*    24:19  4 */
        unsigned int               trylock:1;            /*    24:18  4 */
        unsigned int               read:2;               /*    24:16  4 */
        unsigned int               check:2;              /*    24:14  4 */
        unsigned int               hardirqs_off:1;       /*    24:13  4 */

        /* size: 32, cachelines: 1 */
        /* padding: 4 */
        /* bit_padding: 13 bits */
        /* last cacheline: 32 bytes */
};

[mingo@elte.hu: shrunk hlock->class too]
[peterz@infradead.org: fixup bit sizes]
Signed-off-by: default avatarDave Jones <davej@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
      f82b217e