Re: [PATCH 2/2] tracing: add checks for printing pci devices in mmiotrace.

[Wenji Huang <wenji.huang@oracle.com>]

Steven Rostedt wrote:
> On Thu, 12 Feb 2009, Wenji Huang wrote:
> 
>> This patch is to provide checking return value of trace_seq_printf
>> so as to keep completeness of mmio_print_pcidev.
>>
>> Signed-off-by: Wenji Huang <wenji.huang@oracle.com>
>> ---
>>  kernel/trace/trace_mmiotrace.c |   26 ++++++++++++++++----------
>>  1 files changed, 16 insertions(+), 10 deletions(-)
>>
>> diff --git a/kernel/trace/trace_mmiotrace.c b/kernel/trace/trace_mmiotrace.c
>> index c401b90..ebb0b61 100644
>> --- a/kernel/trace/trace_mmiotrace.c
>> +++ b/kernel/trace/trace_mmiotrace.c
>> @@ -56,17 +56,19 @@ static void mmio_trace_start(struct trace_array *tr)
>>  	mmio_reset_data(tr);
>>  }
>>  
>> -static int mmio_print_pcidev(struct trace_seq *s, const struct pci_dev *dev)
>> +static enum print_line_t mmio_print_pcidev(struct trace_seq *s,
>> +					   const struct pci_dev *dev)
>>  {
>>  	int ret = 0;
>>  	int i;
>>  	resource_size_t start, end;
>>  	const struct pci_driver *drv = pci_dev_driver(dev);
>>  
>> -	/* XXX: incomplete checks for trace_seq_printf() return value */
>> -	ret += trace_seq_printf(s, "PCIDEV %02x%02x %04x%04x %x",
>> +	ret = trace_seq_printf(s, "PCIDEV %02x%02x %04x%04x %x",
>>  				dev->bus->number, dev->devfn,
>>  				dev->vendor, dev->device, dev->irq);
>> +	if (!ret)
>> +		return TRACE_TYPE_PARTIAL_LINE;
>>  	/*
>>  	 * XXX: is pci_resource_to_user() appropriate, since we are
>>  	 * supposed to interpret the __ioremap() phys_addr argument based on
>> @@ -74,21 +76,25 @@ static int mmio_print_pcidev(struct trace_seq *s, const struct pci_dev *dev)
>>  	 */
>>  	for (i = 0; i < 7; i++) {
>>  		pci_resource_to_user(dev, i, &dev->resource[i], &start, &end);
>> -		ret += trace_seq_printf(s, " %llx",
>> +		ret = trace_seq_printf(s, " %llx",
>>  			(unsigned long long)(start |
>>  			(dev->resource[i].flags & PCI_REGION_FLAG_MASK)));
>> -	}
>> -	for (i = 0; i < 7; i++) {
>> +		if (!ret)
>> +			return TRACE_TYPE_PARTIAL_LINE;
> 
> The above looks like a change of logic to me. I'm a bit tired so I can be 
> wrong. But it looks like the original was:
> 
>      for (i = 0; i < 7; i++) {
>              pci_resource_to_user(dev, i, &dev->resource[i], &start, &end);
>              ret += trace_seq_printf(s, " %llx",
>                      (unsigned long long)(start |
>                      (dev->resource[i].flags & PCI_REGION_FLAG_MASK)));
>      }
>      for (i = 0; i < 7; i++) {
>              pci_resource_to_user(dev, i, &dev->resource[i], &start, &end);
>              ret += trace_seq_printf(s, " %llx",
>                      dev->resource[i].start < dev->resource[i].end ?
>                      (unsigned long long)(end - start) + 1 : 0);
>      }
> 
> And the new is:
> 
>      for (i = 0; i < 7; i++) {
>              pci_resource_to_user(dev, i, &dev->resource[i], &start, &end);
>              ret = trace_seq_printf(s, " %llx",   
>                      (unsigned long long)(start |
>                      (dev->resource[i].flags & PCI_REGION_FLAG_MASK)));
>              if (!ret)
>                      return TRACE_TYPE_PARTIAL_LINE;
>              pci_resource_to_user(dev, i, &dev->resource[i], &start, &end);
>              ret = trace_seq_printf(s, " %llx",
>                      dev->resource[i].start < dev->resource[i].end ?
>                      (unsigned long long)(end - start) + 1 : 0);
>              if (!ret)
>                      return TRACE_TYPE_PARTIAL_LINE;
>      }
> 
> This changes the output format.
> 
> Pekka,
> 
> Is this OK?
> 
> -- Steve

oops, output format is changed. Need to update it.


Regards,
wenji