Re: [PATCH] cxl/trace: Initialize cxl_poison region name to NULL

[Ira Weiny <ira.weiny@intel.com>]

alison.schofield@ wrote:
> From: Alison Schofield <alison.schofield@intel.com>
> 
> The TP_STRUCT__entry that gets assigned the region name, or an
> empty string if no region is present, is erroneously initialized
> to the cxl_region pointer. It needs to be initialized to NULL
> otherwise its length is wrong and garbage chars can appear in
> the kernel trace output: /sys/kernel/tracing/trace
> 
> Impact is that tooling depending on that trace data can miss
> picking up a valid event when searching by region name. The
> TP_printk() output, if enabled, does emit the correct region
> names in the dmesg log.
> 
> This was found during testing of the cxl-list option to report
> media-errors for a region.
> 
> Fixes: ddf49d57b841 ("cxl/trace: Add TRACE support for CXL media-error records")
> Signed-off-by: Alison Schofield <alison.schofield@intel.com>
> ---
>  drivers/cxl/core/trace.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/cxl/core/trace.h b/drivers/cxl/core/trace.h
> index bdf117a33744..bc5ca4d530d1 100644
> --- a/drivers/cxl/core/trace.h
> +++ b/drivers/cxl/core/trace.h
> @@ -657,7 +657,7 @@ TRACE_EVENT(cxl_poison,
>  		__string(host, dev_name(cxlmd->dev.parent))
>  		__field(u64, serial)
>  		__field(u8, trace_type)
> -		__string(region, region)
> +		__string(region, NULL)

Couldn't this be "" instead of NULL then remove the __assign_str() if
region is NULL?

Ira

>  		__field(u64, overflow_ts)
>  		__field(u64, hpa)
>  		__field(u64, dpa)
> 
> base-commit: e8f897f4afef0031fe618a8e94127a0934896aba
> -- 
> 2.37.3
> 

k