[PATCH] semaphore: Resolve some shadow warnings

[PATCH] semaphore: Resolve some shadow warnings

[Jeff Kirsher]

From: Mark Rustad <mark.d.rustad@intel.com>

Resolve some shadow warnings resulting from using the name
jiffies, which is a well-known global. This is not a problem
of course, but it could be a trap for someone copying and
pasting code, and it just makes W=2 a little cleaner.

Signed-off-by: Mark Rustad <mark.d.rustad@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
---
 kernel/locking/semaphore.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/kernel/locking/semaphore.c b/kernel/locking/semaphore.c
index 6815171..7782dbc 100644
--- a/kernel/locking/semaphore.c
+++ b/kernel/locking/semaphore.c
@@ -36,7 +36,7 @@
 static noinline void __down(struct semaphore *sem);
 static noinline int __down_interruptible(struct semaphore *sem);
 static noinline int __down_killable(struct semaphore *sem);
-static noinline int __down_timeout(struct semaphore *sem, long jiffies);
+static noinline int __down_timeout(struct semaphore *sem, long njiffies);
 static noinline void __up(struct semaphore *sem);
 
 /**
@@ -145,14 +145,14 @@ EXPORT_SYMBOL(down_trylock);
 /**
  * down_timeout - acquire the semaphore within a specified time
  * @sem: the semaphore to be acquired
- * @jiffies: how long to wait before failing
+ * @njiffies: how long to wait before failing
  *
  * Attempts to acquire the semaphore.  If no more tasks are allowed to
  * acquire the semaphore, calling this function will put the task to sleep.
  * If the semaphore is not released within the specified number of jiffies,
  * this function returns -ETIME.  It returns 0 if the semaphore was acquired.
  */
-int down_timeout(struct semaphore *sem, long jiffies)
+int down_timeout(struct semaphore *sem, long njiffies)
 {
 	unsigned long flags;
 	int result = 0;
@@ -161,7 +161,7 @@ int down_timeout(struct semaphore *sem, long jiffies)
 	if (likely(sem->count > 0))
 		sem->count--;
 	else
-		result = __down_timeout(sem, jiffies);
+		result = __down_timeout(sem, njiffies);
 	raw_spin_unlock_irqrestore(&sem->lock, flags);
 
 	return result;
@@ -248,9 +248,9 @@ static noinline int __sched __down_killable(struct semaphore *sem)
 	return __down_common(sem, TASK_KILLABLE, MAX_SCHEDULE_TIMEOUT);
 }
 
-static noinline int __sched __down_timeout(struct semaphore *sem, long jiffies)
+static noinline int __sched __down_timeout(struct semaphore *sem, long njiffies)
 {
-	return __down_common(sem, TASK_UNINTERRUPTIBLE, jiffies);
+	return __down_common(sem, TASK_UNINTERRUPTIBLE, njiffies);
 }
 
 static noinline void __sched __up(struct semaphore *sem)
-- 
1.9.3

Re: [PATCH] semaphore: Resolve some shadow warnings

[Peter Zijlstra]

On Thu, Aug 28, 2014 at 05:19:26AM -0700, Jeff Kirsher wrote:
> From: Mark Rustad <mark.d.rustad@intel.com>
> 
> Resolve some shadow warnings resulting from using the name
> jiffies, which is a well-known global. This is not a problem
> of course, but it could be a trap for someone copying and
> pasting code, and it just makes W=2 a little cleaner.
> 
> Signed-off-by: Mark Rustad <mark.d.rustad@intel.com>
> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

Why isn't Mark sending this email?

> ---
>  kernel/locking/semaphore.c | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/kernel/locking/semaphore.c b/kernel/locking/semaphore.c
> index 6815171..7782dbc 100644
> --- a/kernel/locking/semaphore.c
> +++ b/kernel/locking/semaphore.c
> @@ -36,7 +36,7 @@
>  static noinline void __down(struct semaphore *sem);
>  static noinline int __down_interruptible(struct semaphore *sem);
>  static noinline int __down_killable(struct semaphore *sem);
> -static noinline int __down_timeout(struct semaphore *sem, long jiffies);
> +static noinline int __down_timeout(struct semaphore *sem, long njiffies);
>  static noinline void __up(struct semaphore *sem);

So what's wrong with calling it "timeout" instead? That's what most
other sites do.

Re: [PATCH] semaphore: Resolve some shadow warnings

[Jeff Kirsher]

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On Mon, 2014-09-01 at 14:02 +0200, Peter Zijlstra wrote:
> On Thu, Aug 28, 2014 at 05:19:26AM -0700, Jeff Kirsher wrote:
> > From: Mark Rustad <mark.d.rustad@intel.com>
> > 
> > Resolve some shadow warnings resulting from using the name
> > jiffies, which is a well-known global. This is not a problem
> > of course, but it could be a trap for someone copying and
> > pasting code, and it just makes W=2 a little cleaner.
> > 
> > Signed-off-by: Mark Rustad <mark.d.rustad@intel.com>
> > Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
> 
> Why isn't Mark sending this email?

Mark sent me several patches like this, for me to push upstream.  So, I
am making sure the appropriate owner is the receives the patch versus
blindly sending to LKML.

> 
> > ---
> >  kernel/locking/semaphore.c | 12 ++++++------
> >  1 file changed, 6 insertions(+), 6 deletions(-)
> > 
> > diff --git a/kernel/locking/semaphore.c b/kernel/locking/semaphore.c
> > index 6815171..7782dbc 100644
> > --- a/kernel/locking/semaphore.c
> > +++ b/kernel/locking/semaphore.c
> > @@ -36,7 +36,7 @@
> >  static noinline void __down(struct semaphore *sem);
> >  static noinline int __down_interruptible(struct semaphore *sem);
> >  static noinline int __down_killable(struct semaphore *sem);
> > -static noinline int __down_timeout(struct semaphore *sem, long jiffies);
> > +static noinline int __down_timeout(struct semaphore *sem, long njiffies);
> >  static noinline void __up(struct semaphore *sem);
> 
> So what's wrong with calling it "timeout" instead? That's what most
> other sites do.

Timeout would work as well to resolve the shadow warnings.

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Re: [PATCH] semaphore: Resolve some shadow warnings

[Rustad, Mark D]

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On Sep 1, 2014, at 4:41 PM, Jeff Kirsher <jeffrey.t.kirsher@intel.com> wrote:

> On Mon, 2014-09-01 at 14:02 +0200, Peter Zijlstra wrote:
>> On Thu, Aug 28, 2014 at 05:19:26AM -0700, Jeff Kirsher wrote:
>>> From: Mark Rustad <mark.d.rustad@intel.com>
>>> 
>>> Resolve some shadow warnings resulting from using the name
>>> jiffies, which is a well-known global. This is not a problem
>>> of course, but it could be a trap for someone copying and
>>> pasting code, and it just makes W=2 a little cleaner.
>>> 
>>> Signed-off-by: Mark Rustad <mark.d.rustad@intel.com>
>>> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
>> 
>> Why isn't Mark sending this email?
> 
> Mark sent me several patches like this, for me to push upstream.  So, I
> am making sure the appropriate owner is the receives the patch versus
> blindly sending to LKML.
> 
>> 
>>> ---
>>> kernel/locking/semaphore.c | 12 ++++++------
>>> 1 file changed, 6 insertions(+), 6 deletions(-)
>>> 
>>> diff --git a/kernel/locking/semaphore.c b/kernel/locking/semaphore.c
>>> index 6815171..7782dbc 100644
>>> --- a/kernel/locking/semaphore.c
>>> +++ b/kernel/locking/semaphore.c
>>> @@ -36,7 +36,7 @@
>>> static noinline void __down(struct semaphore *sem);
>>> static noinline int __down_interruptible(struct semaphore *sem);
>>> static noinline int __down_killable(struct semaphore *sem);
>>> -static noinline int __down_timeout(struct semaphore *sem, long jiffies);
>>> +static noinline int __down_timeout(struct semaphore *sem, long njiffies);
>>> static noinline void __up(struct semaphore *sem);
>> 
>> So what's wrong with calling it "timeout" instead? That's what most
>> other sites do.
> 
> Timeout would work as well to resolve the shadow warnings.

It would, but then it would be unclear as to what units the timeout was in. I have no other objection to timeout, I was just trying to preserve the meaning in the existing overloaded name. The "n" to me suggests a number and, if anything, number of jiffies conveys a more precise meaning than simply jiffies did.

-- 
Mark Rustad, Networking Division, Intel Corporation


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Re: [PATCH] semaphore: Resolve some shadow warnings

[Peter Zijlstra]

On Tue, Sep 02, 2014 at 09:16:23PM +0000, Rustad, Mark D wrote:
> 
> It would, but then it would be unclear as to what units the timeout
> was in. I have no other objection to timeout, I was just trying to
> preserve the meaning in the existing overloaded name. The "n" to me
> suggests a number and, if anything, number of jiffies conveys a more
> precise meaning than simply jiffies did.

Use a comment for the unit. If you look you'll find tons of 'timeout'
variables that measure in jiffies (and others of course).