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SubjectRe: [PATCH 13/26] locking: Add non-fatal spin lock assert
On 09/03/2014 10:40 AM, Peter Zijlstra wrote:
> On Wed, Sep 03, 2014 at 07:20:04AM -0400, Peter Hurley wrote:
>> Hi Peter,
>>
>> On 09/03/2014 05:27 AM, Peter Zijlstra wrote:
>>> On Tue, Sep 02, 2014 at 05:39:22PM -0400, Peter Hurley wrote:
>>>> Provide method for non-essential or non-critical code to warn of
>>>> invariant errors.
>>>>
>>>> CC: Ingo Molnar <mingo@kernel.org>
>>>> CC: Peter Zijlstra <peterz@infradead.org>
>>>> CC: Thomas Gleixner <tglx@linutronix.de>
>>>> Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
>>>> ---
>>>> include/linux/spinlock.h | 1 +
>>>> include/linux/spinlock_api_smp.h | 1 +
>>>> include/linux/spinlock_api_up.h | 1 +
>>>> 3 files changed, 3 insertions(+)
>>>>
>>>> diff --git a/include/linux/spinlock.h b/include/linux/spinlock.h
>>>> index 3f2867f..8a9aaf1 100644
>>>> --- a/include/linux/spinlock.h
>>>> +++ b/include/linux/spinlock.h
>>>> @@ -394,6 +394,7 @@ static inline int spin_can_lock(spinlock_t *lock)
>>>> }
>>>>
>>>> #define assert_spin_locked(lock) assert_raw_spin_locked(&(lock)->rlock)
>>>> +#define warn_not_spin_locked(lock) warn_not_raw_spin_locked(&(lock)->rlock)
>>>>
>>>> /*
>>>> * Pull the atomic_t declaration:
>>>> diff --git a/include/linux/spinlock_api_smp.h b/include/linux/spinlock_api_smp.h
>>>> index 42dfab8..0ddd499 100644
>>>> --- a/include/linux/spinlock_api_smp.h
>>>> +++ b/include/linux/spinlock_api_smp.h
>>>> @@ -18,6 +18,7 @@
>>>> int in_lock_functions(unsigned long addr);
>>>>
>>>> #define assert_raw_spin_locked(x) BUG_ON(!raw_spin_is_locked(x))
>>>> +#define warn_not_raw_spin_locked(x) WARN_ON_ONCE(!raw_spin_is_locked(x))
>>>
>>> No we should remove assert_spin_locked() not add to it. Use
>>> lockdep_assert_held() instead.
>>
>> I probably should have been more descriptive in the changelog: this
>> is not for a test configuration, but rather, an assertion in an
>> exported api.
>
> So ?

So a lockdep-only assert is unlikely to draw attention to existing bugs,
especially in established drivers.



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