From: John Hubbard <[email protected]>
Commit 0d2cc3b34532 ("locking/lockdep: Move valid_state() inside
CONFIG_TRACE_IRQFLAGS && CONFIG_PROVE_LOCKING") moved the only usage of
print_lock_trace() that was originally outside of the CONFIG_PROVE_LOCKING
case. It moved that usage into a different case: CONFIG_PROVE_LOCKING &&
CONFIG_TRACE_IRQFLAGS. That leaves things not symmetrical, and as a result,
the following warning fires on my build, when I have
!CONFIG_TRACE_IRQFLAGS && !CONFIG_PROVE_LOCKING
set:
kernel/locking/lockdep.c:2821:13: warning: ‘print_lock_trace’ defined
but not used [-Wunused-function]
Fix this by only defining print_lock_trace() in cases in which is it
called.
Fixes: 0d2cc3b34532 ("locking/lockdep: Move valid_state() inside CONFIG_TRACE_IRQFLAGS && CONFIG_PROVE_LOCKING")
Cc: Frederic Weisbecker <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Paul E. McKenney <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Will Deacon <[email protected]>
Signed-off-by: John Hubbard <[email protected]>
---
kernel/locking/lockdep.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index d06190fa5082..3065dc36c27a 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -2817,11 +2817,14 @@ static inline int validate_chain(struct task_struct *curr,
return 1;
}
+#if defined(CONFIG_TRACE_IRQFLAGS)
static void print_lock_trace(struct lock_trace *trace, unsigned int spaces)
{
}
#endif
+#endif
+
/*
* We are building curr_chain_key incrementally, so double-check
* it from scratch, to make sure that it's done correctly:
--
2.21.0
On Tue, May 21, 2019 at 12:08:08AM -0700, [email protected] wrote:
> From: John Hubbard <[email protected]>
>
> Commit 0d2cc3b34532 ("locking/lockdep: Move valid_state() inside
> CONFIG_TRACE_IRQFLAGS && CONFIG_PROVE_LOCKING") moved the only usage of
> print_lock_trace() that was originally outside of the CONFIG_PROVE_LOCKING
> case. It moved that usage into a different case: CONFIG_PROVE_LOCKING &&
> CONFIG_TRACE_IRQFLAGS. That leaves things not symmetrical, and as a result,
> the following warning fires on my build, when I have
>
> !CONFIG_TRACE_IRQFLAGS && !CONFIG_PROVE_LOCKING
>
> set:
>
> kernel/locking/lockdep.c:2821:13: warning: ‘print_lock_trace’ defined
> but not used [-Wunused-function]
>
> Fix this by only defining print_lock_trace() in cases in which is it
> called.
>
> Fixes: 0d2cc3b34532 ("locking/lockdep: Move valid_state() inside CONFIG_TRACE_IRQFLAGS && CONFIG_PROVE_LOCKING")
> Cc: Frederic Weisbecker <[email protected]>
> Cc: Andrew Morton <[email protected]>
> Cc: Linus Torvalds <[email protected]>
> Cc: Paul E. McKenney <[email protected]>
> Cc: Peter Zijlstra <[email protected]>
> Cc: Thomas Gleixner <[email protected]>
> Cc: Will Deacon <[email protected]>
> Signed-off-by: John Hubbard <[email protected]>
> ---
> kernel/locking/lockdep.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
> index d06190fa5082..3065dc36c27a 100644
> --- a/kernel/locking/lockdep.c
> +++ b/kernel/locking/lockdep.c
> @@ -2817,11 +2817,14 @@ static inline int validate_chain(struct task_struct *curr,
> return 1;
> }
>
> +#if defined(CONFIG_TRACE_IRQFLAGS)
> static void print_lock_trace(struct lock_trace *trace, unsigned int spaces)
This works, but another approach is to put "__maybe_unused" in the
above declaration, which avoids the need to have "#if" in a .c file.
But this file already has quite a few #if and #ifdef commands, so maybe
it is OK here.
Also, "#ifdef CONFIG_TRACE_IRQFLAGS" is a bit more conventional than
the above, should the "__maybe_unused" be undesirable.
Yet another approach is to move this function to include/linux/lockdep.h,
where #ifdef is considered less objectionable.
But I must defer to the maintainers.
Thanx, Paul
> {
> }
> #endif
>
> +#endif
> +
> /*
> * We are building curr_chain_key incrementally, so double-check
> * it from scratch, to make sure that it's done correctly:
> --
> 2.21.0
>
On 6/9/19 6:51 AM, Paul E. McKenney wrote:
> On Tue, May 21, 2019 at 12:08:08AM -0700, [email protected] wrote:
>> From: John Hubbard <[email protected]>
>>
>> Commit 0d2cc3b34532 ("locking/lockdep: Move valid_state() inside
>> CONFIG_TRACE_IRQFLAGS && CONFIG_PROVE_LOCKING") moved the only usage of
>> print_lock_trace() that was originally outside of the CONFIG_PROVE_LOCKING
>> case. It moved that usage into a different case: CONFIG_PROVE_LOCKING &&
>> CONFIG_TRACE_IRQFLAGS. That leaves things not symmetrical, and as a result,
>> the following warning fires on my build, when I have
>>
>> !CONFIG_TRACE_IRQFLAGS && !CONFIG_PROVE_LOCKING
>>
>> set:
>>
>> kernel/locking/lockdep.c:2821:13: warning: ‘print_lock_trace’ defined
>> but not used [-Wunused-function]
>>
>> Fix this by only defining print_lock_trace() in cases in which is it
>> called.
>>
>> Fixes: 0d2cc3b34532 ("locking/lockdep: Move valid_state() inside CONFIG_TRACE_IRQFLAGS && CONFIG_PROVE_LOCKING")
>> Cc: Frederic Weisbecker <[email protected]>
>> Cc: Andrew Morton <[email protected]>
>> Cc: Linus Torvalds <[email protected]>
>> Cc: Paul E. McKenney <[email protected]>
>> Cc: Peter Zijlstra <[email protected]>
>> Cc: Thomas Gleixner <[email protected]>
>> Cc: Will Deacon <[email protected]>
>> Signed-off-by: John Hubbard <[email protected]>
>> ---
>> kernel/locking/lockdep.c | 3 +++
>> 1 file changed, 3 insertions(+)
>>
>> diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
>> index d06190fa5082..3065dc36c27a 100644
>> --- a/kernel/locking/lockdep.c
>> +++ b/kernel/locking/lockdep.c
>> @@ -2817,11 +2817,14 @@ static inline int validate_chain(struct task_struct *curr,
>> return 1;
>> }
>>
>> +#if defined(CONFIG_TRACE_IRQFLAGS)
>> static void print_lock_trace(struct lock_trace *trace, unsigned int spaces)
>
> This works, but another approach is to put "__maybe_unused" in the
> above declaration, which avoids the need to have "#if" in a .c file.
Good idea, that approach appeals to me here, because tracing is a natural fit
for "might not be used" types of functions.
> But this file already has quite a few #if and #ifdef commands, so maybe
> it is OK here.
>
> Also, "#ifdef CONFIG_TRACE_IRQFLAGS" is a bit more conventional than
> the above, should the "__maybe_unused" be undesirable.
ah, OK, I'll keep that in mind. (The two seemed identical to my mind, but
it's good to make things look like surrounding code, of course.)
thanks,
--
John Hubbard
NVIDIA
>
> Yet another approach is to move this function to include/linux/lockdep.h,
> where #ifdef is considered less objectionable.
>
> But I must defer to the maintainers.
>
> Thanx, Paul
From: John Hubbard <[email protected]>
Commit 0d2cc3b34532 ("locking/lockdep: Move valid_state() inside
CONFIG_TRACE_IRQFLAGS && CONFIG_PROVE_LOCKING") moved the only usage of
print_lock_trace() that was originally outside of the CONFIG_PROVE_LOCKING
case. It moved that usage into a different case: CONFIG_PROVE_LOCKING &&
CONFIG_TRACE_IRQFLAGS. That leaves things not symmetrical, and as a result,
the following warning fires on my build, when I have
!CONFIG_TRACE_IRQFLAGS && !CONFIG_PROVE_LOCKING
set:
kernel/locking/lockdep.c:2821:13: warning: ‘print_lock_trace’ defined
but not used [-Wunused-function]
Fix this by annotating print_lock_trace() with "__maybe_unused".
Thanks to Paul E. McKenney for suggesting this less intrusive fix,
as compared to adding more ifdef noise.
Fixes: 0d2cc3b34532 ("locking/lockdep: Move valid_state() inside CONFIG_TRACE_IRQFLAGS && CONFIG_PROVE_LOCKING")
Cc: Frederic Weisbecker <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Paul E. McKenney <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Will Deacon <[email protected]>
Signed-off-by: John Hubbard <[email protected]>
---
kernel/locking/lockdep.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index c47788fa85f9..2726dafdb29b 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -2818,7 +2818,8 @@ static inline int validate_chain(struct task_struct *curr,
return 1;
}
-static void print_lock_trace(struct lock_trace *trace, unsigned int spaces)
+static void __maybe_unused print_lock_trace(struct lock_trace *trace,
+ unsigned int spaces)
{
}
#endif
--
2.21.0
On Sun, Jun 09, 2019 at 05:09:33PM -0700, [email protected] wrote:
> From: John Hubbard <[email protected]>
>
> Commit 0d2cc3b34532 ("locking/lockdep: Move valid_state() inside
> CONFIG_TRACE_IRQFLAGS && CONFIG_PROVE_LOCKING") moved the only usage of
> print_lock_trace() that was originally outside of the CONFIG_PROVE_LOCKING
> case. It moved that usage into a different case: CONFIG_PROVE_LOCKING &&
> CONFIG_TRACE_IRQFLAGS. That leaves things not symmetrical, and as a result,
> the following warning fires on my build, when I have
>
> !CONFIG_TRACE_IRQFLAGS && !CONFIG_PROVE_LOCKING
>
> set:
>
> kernel/locking/lockdep.c:2821:13: warning: ‘print_lock_trace’ defined
> but not used [-Wunused-function]
>
> Fix this by annotating print_lock_trace() with "__maybe_unused".
> Thanks to Paul E. McKenney for suggesting this less intrusive fix,
> as compared to adding more ifdef noise.
>
> Fixes: 0d2cc3b34532 ("locking/lockdep: Move valid_state() inside CONFIG_TRACE_IRQFLAGS && CONFIG_PROVE_LOCKING")
>
> Cc: Frederic Weisbecker <[email protected]>
> Cc: Andrew Morton <[email protected]>
> Cc: Linus Torvalds <[email protected]>
> Cc: Paul E. McKenney <[email protected]>
> Cc: Peter Zijlstra <[email protected]>
> Cc: Thomas Gleixner <[email protected]>
> Cc: Will Deacon <[email protected]>
> Signed-off-by: John Hubbard <[email protected]>
Tested-by: Paul E. McKenney <[email protected]>
> ---
> kernel/locking/lockdep.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
> index c47788fa85f9..2726dafdb29b 100644
> --- a/kernel/locking/lockdep.c
> +++ b/kernel/locking/lockdep.c
> @@ -2818,7 +2818,8 @@ static inline int validate_chain(struct task_struct *curr,
> return 1;
> }
>
> -static void print_lock_trace(struct lock_trace *trace, unsigned int spaces)
> +static void __maybe_unused print_lock_trace(struct lock_trace *trace,
> + unsigned int spaces)
> {
> }
> #endif
> --
> 2.21.0
>