context imbalance false positive sparse warnings

context imbalance false positive sparse warnings

[Steve French]

Just building one directory of the kernel (./fs/*.c), ie "make bzImage
C=1" generates more than 200 sparse warnings similar to
       warning: context imbalance in 'set_task_ioprio': wrong count at exit

Even the simplest use cases throw this error e.g. fs/super.c line 162-164:

static void put_super(struct super_block *sb)
{
       spin_lock(&sb_lock);
       __put_super(sb);
       spin_unlock(&sb_lock);
}


It doesn't look like sparse has been fixed in a few months, unless the
sparse tool repository has moved from the
    /pub/scm / devel/sparse/sparse.git
directory on git.kernel.org

Is there a way to turn just this warning off (the thousands of context
imbalance messages generated by the kernel build make it harder to see
real errors which sparse could catch)?


-- 
Thanks,

Steve

Re: context imbalance false positive sparse warnings

[Stalin Kenny]

> Even the simplest use cases throw this error e.g. fs/super.c line 162-164:
>
> static void put_super(struct super_block *sb)
> {
>       spin_lock(&sb_lock);
>       __put_super(sb);
>       spin_unlock(&sb_lock);
> }

What is the sparse error when you call this function ?


On 8/19/08, Steve French <smfrench@gmail.com> wrote:
> Just building one directory of the kernel (./fs/*.c), ie "make bzImage
> C=1" generates more than 200 sparse warnings similar to
>       warning: context imbalance in 'set_task_ioprio': wrong count at exit
>
> Even the simplest use cases throw this error e.g. fs/super.c line 162-164:
>
> static void put_super(struct super_block *sb)
> {
>       spin_lock(&sb_lock);
>       __put_super(sb);
>       spin_unlock(&sb_lock);
> }
>
>
> It doesn't look like sparse has been fixed in a few months, unless the
> sparse tool repository has moved from the
>    /pub/scm / devel/sparse/sparse.git
> directory on git.kernel.org
>
> Is there a way to turn just this warning off (the thousands of context
> imbalance messages generated by the kernel build make it harder to see
> real errors which sparse could catch)?
>
>
> --
> Thanks,
>
> Steve
> --
> To unsubscribe from this list: send the line "unsubscribe linux-sparse" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>

Re: context imbalance false positive sparse warnings

[Steve French]

On Tue, Aug 19, 2008 at 5:00 PM, Stalin Kenny <stalinlinux@gmail.com> wrote:
>> Even the simplest use cases throw this error e.g. fs/super.c line 162-164:
>>
>> static void put_super(struct super_block *sb)
>> {
>>       spin_lock(&sb_lock);
>>       __put_super(sb);
>>       spin_unlock(&sb_lock);
>> }
>
> What is the sparse error when you call this function ?
CHECK   fs/super.c
fs/super.c:164:2: warning: context imbalance in 'put_super': wrong count at exit
fs/super.c:164:2:    context 'lock': wanted 0, got 1




>
> On 8/19/08, Steve French <smfrench@gmail.com> wrote:
>> Just building one directory of the kernel (./fs/*.c), ie "make bzImage
>> C=1" generates more than 200 sparse warnings similar to
>>       warning: context imbalance in 'set_task_ioprio': wrong count at exit
>>
>> Even the simplest use cases throw this error e.g. fs/super.c line 162-164:
>>
>> static void put_super(struct super_block *sb)
>> {
>>       spin_lock(&sb_lock);
>>       __put_super(sb);
>>       spin_unlock(&sb_lock);
>> }
>>
>>
>> It doesn't look like sparse has been fixed in a few months, unless the
>> sparse tool repository has moved from the
>>    /pub/scm / devel/sparse/sparse.git
>> directory on git.kernel.org
>>
>> Is there a way to turn just this warning off (the thousands of context
>> imbalance messages generated by the kernel build make it harder to see
>> real errors which sparse could catch)?
>>
>>
>> --
>> Thanks,
>>
>> Steve
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-sparse" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>
>



-- 
Thanks,

Steve

Re: context imbalance false positive sparse warnings

[Harvey Harrison]

On Tue, 2008-08-19 at 17:22 -0500, Steve French wrote:
> On Tue, Aug 19, 2008 at 5:00 PM, Stalin Kenny <stalinlinux@gmail.com> wrote:
> >> Even the simplest use cases throw this error e.g. fs/super.c line 162-164:
> >>
> >> static void put_super(struct super_block *sb)
> >> {
> >>       spin_lock(&sb_lock);
> >>       __put_super(sb);
> >>       spin_unlock(&sb_lock);
> >> }
> >
> > What is the sparse error when you call this function ?
> CHECK   fs/super.c
> fs/super.c:164:2: warning: context imbalance in 'put_super': wrong count at exit
> fs/super.c:164:2:    context 'lock': wanted 0, got 1
> 
> 

Johannes Berg had a 9-patch series that improved this somewhat, but they had
some bugs in them (crashes).  But I've been running with them anyway as they
do improve cases like this significantly.

Harvey

Re: context imbalance false positive sparse warnings

[Johannes Berg]

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On Tue, 2008-08-19 at 15:26 -0700, Harvey Harrison wrote:
> On Tue, 2008-08-19 at 17:22 -0500, Steve French wrote:
> > On Tue, Aug 19, 2008 at 5:00 PM, Stalin Kenny <stalinlinux@gmail.com> wrote:
> > >> Even the simplest use cases throw this error e.g. fs/super.c line 162-164:
> > >>
> > >> static void put_super(struct super_block *sb)
> > >> {
> > >>       spin_lock(&sb_lock);
> > >>       __put_super(sb);
> > >>       spin_unlock(&sb_lock);
> > >> }
> > >
> > > What is the sparse error when you call this function ?
> > CHECK   fs/super.c
> > fs/super.c:164:2: warning: context imbalance in 'put_super': wrong count at exit
> > fs/super.c:164:2:    context 'lock': wanted 0, got 1
> > 
> > 
> 
> Johannes Berg had a 9-patch series that improved this somewhat, but they had
> some bugs in them (crashes).  But I've been running with them anyway as they
> do improve cases like this significantly.

I've just sent out a fixed version and with it I get no errors on
fs/super.c when I apply this small fixup:

diff --git a/fs/super.c b/fs/super.c
index e931ae9..6810845 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -201,7 +201,7 @@ EXPORT_SYMBOL(deactivate_super);
  *	success, 0 if we had failed (superblock contents was already dead or
  *	dying when grab_super() had been called).
  */
-static int grab_super(struct super_block *s) __releases(sb_lock)
+static int grab_super(struct super_block *s) __releases(&sb_lock)
 {
 	s->s_count++;
 	spin_unlock(&sb_lock);

johannes

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