* [PATCH 0/1] lockdep: fix warning: print_lock_trace defined but not used
@ 2019-05-21 7:08 john.hubbard
2019-05-21 7:08 ` [PATCH 1/1] " john.hubbard
0 siblings, 1 reply; 6+ messages in thread
From: john.hubbard @ 2019-05-21 7:08 UTC (permalink / raw)
To: LKML
Cc: John Hubbard, Frederic Weisbecker, Andrew Morton, Linus Torvalds,
Paul E . McKenney, Peter Zijlstra, Thomas Gleixner, Will Deacon
From: John Hubbard <jhubbard@nvidia.com>
Hi,
This is a second attempt to send this. The first attempt [1]
went via mailgw.nvidia.com, and did not receive a DKIM signature,
so I think it probably got discarded by many systems.
This one goes via gmail, which is what I was using before. We'll keep
working on getting the NVIDIA outgoing email servers working
with mailing lists, but meanwhile I'm back to using "envelope"
techniques, I guess. I was hoping to use a "native" email
address, but not quite there yet. :)
Anyway, here's the original cover letter:
I ran across this minor warning while building against today's linux.git.
The proposed trivial fix leaves it a little fragile from a "what if someone
adds a new call to print_lock_trace()" point of view, but I believe that it
makes the current combination of ifdefs accurate, anyway.
[1] https://lkml.org/lkml/2019/5/19/60
Cc: Frederic Weisbecker <frederic@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
John Hubbard (1):
lockdep: fix warning: print_lock_trace defined but not used
kernel/locking/lockdep.c | 3 +++
1 file changed, 3 insertions(+)
--
2.21.0
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH 1/1] lockdep: fix warning: print_lock_trace defined but not used
2019-05-21 7:08 [PATCH 0/1] lockdep: fix warning: print_lock_trace defined but not used john.hubbard
@ 2019-05-21 7:08 ` john.hubbard
2019-06-09 13:51 ` Paul E. McKenney
0 siblings, 1 reply; 6+ messages in thread
From: john.hubbard @ 2019-05-21 7:08 UTC (permalink / raw)
To: LKML
Cc: John Hubbard, Frederic Weisbecker, Andrew Morton, Linus Torvalds,
Paul E . McKenney, Peter Zijlstra, Thomas Gleixner, Will Deacon
From: John Hubbard <jhubbard@nvidia.com>
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 <frederic@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
---
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
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH 1/1] lockdep: fix warning: print_lock_trace defined but not used
2019-05-21 7:08 ` [PATCH 1/1] " john.hubbard
@ 2019-06-09 13:51 ` Paul E. McKenney
2019-06-09 23:38 ` John Hubbard
2019-06-10 0:09 ` [PATCH v2] " john.hubbard
0 siblings, 2 replies; 6+ messages in thread
From: Paul E. McKenney @ 2019-06-09 13:51 UTC (permalink / raw)
To: john.hubbard
Cc: LKML, John Hubbard, Frederic Weisbecker, Andrew Morton,
Linus Torvalds, Peter Zijlstra, Thomas Gleixner, Will Deacon
On Tue, May 21, 2019 at 12:08:08AM -0700, john.hubbard@gmail.com wrote:
> From: John Hubbard <jhubbard@nvidia.com>
>
> 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 <frederic@kernel.org>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Linus Torvalds <torvalds@linux-foundation.org>
> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Will Deacon <will.deacon@arm.com>
> Signed-off-by: John Hubbard <jhubbard@nvidia.com>
> ---
> 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
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH 1/1] lockdep: fix warning: print_lock_trace defined but not used
2019-06-09 13:51 ` Paul E. McKenney
@ 2019-06-09 23:38 ` John Hubbard
2019-06-10 0:09 ` [PATCH v2] " john.hubbard
1 sibling, 0 replies; 6+ messages in thread
From: John Hubbard @ 2019-06-09 23:38 UTC (permalink / raw)
To: paulmck, john.hubbard
Cc: LKML, Frederic Weisbecker, Andrew Morton, Linus Torvalds,
Peter Zijlstra, Thomas Gleixner, Will Deacon
On 6/9/19 6:51 AM, Paul E. McKenney wrote:
> On Tue, May 21, 2019 at 12:08:08AM -0700, john.hubbard@gmail.com wrote:
>> From: John Hubbard <jhubbard@nvidia.com>
>>
>> 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 <frederic@kernel.org>
>> Cc: Andrew Morton <akpm@linux-foundation.org>
>> Cc: Linus Torvalds <torvalds@linux-foundation.org>
>> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
>> Cc: Peter Zijlstra <peterz@infradead.org>
>> Cc: Thomas Gleixner <tglx@linutronix.de>
>> Cc: Will Deacon <will.deacon@arm.com>
>> Signed-off-by: John Hubbard <jhubbard@nvidia.com>
>> ---
>> 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
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH v2] lockdep: fix warning: print_lock_trace defined but not used
2019-06-09 13:51 ` Paul E. McKenney
2019-06-09 23:38 ` John Hubbard
@ 2019-06-10 0:09 ` john.hubbard
2019-06-18 16:00 ` Paul E. McKenney
1 sibling, 1 reply; 6+ messages in thread
From: john.hubbard @ 2019-06-10 0:09 UTC (permalink / raw)
To: LKML
Cc: John Hubbard, Frederic Weisbecker, Andrew Morton, Linus Torvalds,
Paul E . McKenney, Peter Zijlstra, Thomas Gleixner, Will Deacon
From: John Hubbard <jhubbard@nvidia.com>
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 <frederic@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
---
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
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH v2] lockdep: fix warning: print_lock_trace defined but not used
2019-06-10 0:09 ` [PATCH v2] " john.hubbard
@ 2019-06-18 16:00 ` Paul E. McKenney
0 siblings, 0 replies; 6+ messages in thread
From: Paul E. McKenney @ 2019-06-18 16:00 UTC (permalink / raw)
To: john.hubbard
Cc: LKML, John Hubbard, Frederic Weisbecker, Andrew Morton,
Linus Torvalds, Peter Zijlstra, Thomas Gleixner, Will Deacon
On Sun, Jun 09, 2019 at 05:09:33PM -0700, john.hubbard@gmail.com wrote:
> From: John Hubbard <jhubbard@nvidia.com>
>
> 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 <frederic@kernel.org>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Linus Torvalds <torvalds@linux-foundation.org>
> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Will Deacon <will.deacon@arm.com>
> Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Tested-by: Paul E. McKenney <paulmck@linux.ibm.com>
> ---
> 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
>
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2019-06-18 16:01 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
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2019-05-21 7:08 [PATCH 0/1] lockdep: fix warning: print_lock_trace defined but not used john.hubbard
2019-05-21 7:08 ` [PATCH 1/1] " john.hubbard
2019-06-09 13:51 ` Paul E. McKenney
2019-06-09 23:38 ` John Hubbard
2019-06-10 0:09 ` [PATCH v2] " john.hubbard
2019-06-18 16:00 ` Paul E. McKenney
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