Re: [PATCH v2 2/2] staging: ion: chunk_heap: use %pad for printing dma_addr_t's

[Colin Cross]

On Mon, May 4, 2015 at 1:22 AM, Dan Carpenter <dan.carpenter@xxxxxxxxxx> wrote:
> On Thu, Apr 09, 2015 at 06:10:04PM -0700, Mitchel Humpherys wrote:
>> We're currently using %lu and %ld to print some variables of type
>> dma_addr_t, which results in the following warning when dma_addr_t is
>> 64-bits wide:
>>
>>     drivers/staging/android/ion/ion_chunk_heap.c: In function 'ion_chunk_heap_create':
>>     drivers/staging/android/ion/ion_chunk_heap.c:176:2: warning: format '%lu' expects argument of type 'long unsigned int', but argument 3 has type 'dma_addr_t' [-Wformat=]
>>       pr_info("%s: base %lu size %zu align %ld\n", __func__, chunk_heap->base,
>>       ^
>>     drivers/staging/android/ion/ion_chunk_heap.c:176:2: warning: format '%ld' expects argument of type 'long int', but argument 5 has type 'dma_addr_t' [-Wformat=]
>>
>> Fix this by using %pad as instructed in printk-formats.txt.
>>
>> Signed-off-by: Mitchel Humpherys <mitchelh@xxxxxxxxxxxxxx>
>
> This one was just merged and I was about to email you that it introduces
> some new Smatch warnings, but actually looking at it, it's just wrong.
>
> We want to print "chunk_heap->base" and not "&chunk_heap->base".

This would be correct if base was a dma_addr_t...

> And anyway "&chunk_heap->base" is a regular pointer, not a dma_addr_t.

But it is actually an ion_phys_addr_t, which is currently typedef'd to
unsigned long.  Are you using a local patch that replaces
ion_phys_addr_t with dma_addr_t?

> So please send a new patch that removes the &.

Removing the & is not correct, lib/vsprintf.c will dereference the arg
for %pad or %pap.  I think this patch should just be dropped, the old
%lu was correct for what is in Linus' tree.

> regards,
> dan carpenter
>
>> ---
>>  drivers/staging/android/ion/ion_chunk_heap.c | 4 ++--
>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/staging/android/ion/ion_chunk_heap.c b/drivers/staging/android/ion/ion_chunk_heap.c
>> index 54746157d799..6b3e18aa1c64 100644
>> --- a/drivers/staging/android/ion/ion_chunk_heap.c
>> +++ b/drivers/staging/android/ion/ion_chunk_heap.c
>> @@ -173,8 +173,8 @@ struct ion_heap *ion_chunk_heap_create(struct ion_platform_heap *heap_data)
>>       chunk_heap->heap.ops = &chunk_heap_ops;
>>       chunk_heap->heap.type = ION_HEAP_TYPE_CHUNK;
>>       chunk_heap->heap.flags = ION_HEAP_FLAG_DEFER_FREE;
>> -     pr_debug("%s: base %lu size %zu align %ld\n", __func__, chunk_heap->base,
>> -             heap_data->size, heap_data->align);
>> +     pr_debug("%s: base %pad size %zu align %pad\n", __func__,
>> +             &chunk_heap->base, heap_data->size, &heap_data->align);
>>
>>       return &chunk_heap->heap;
>>
>> --
>> Qualcomm Innovation Center, Inc.
>> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
>> a Linux Foundation Collaborative Project
>>
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>
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