[Crash-utility] [PATCH] extensions/trace: max_buffer is optional

[Dave Anderson]

Rabin,

This looks fine to me -- Qiao, can you please ACK this patch?

Thanks,
  Dave


----- Original Message -----
> max_buffer is optional in the kernel (depends on the
> CONFIG_TRACE_MAX_TRACE option).  Don't fail if it isn't available.
> ---
>  extensions/trace.c |   14 +++++++++++++-
>  1 file changed, 13 insertions(+), 1 deletion(-)
> 
> diff --git a/extensions/trace.c b/extensions/trace.c
> index 9f81568..c269f4c 100644
> --- a/extensions/trace.c
> +++ b/extensions/trace.c
> @@ -34,6 +34,10 @@ static int encapsulated_current_trace;
>   * trace_buffer is supported
>   */
>  static int trace_buffer_available;
> +/*
> + * max_buffer is supported
> + */
> +static int max_buffer_available;
>  
>  #define koffset(struct, member) struct##_##member##_offset
>  
> @@ -163,8 +167,10 @@ static int init_offsets(void)
>  
>  	if (trace_buffer_available) {
>  		init_offset(trace_array, trace_buffer);
> -		init_offset(trace_array, max_buffer);
>  		init_offset(trace_buffer, buffer);
> +
> +		if (max_buffer_available)
> +			init_offset(trace_array, max_buffer);
>  	} else {
>  		init_offset(trace_array, buffer);
>  	}
> @@ -448,6 +454,9 @@ out_fail:
>  static int ftrace_int_max_tr_trace(void)
>  {
>  	if (trace_buffer_available) {
> +		if (!max_buffer_available)
> +			return 0;
> +
>  		global_max_buffer = global_trace + koffset(trace_array, max_buffer);
>  		read_value(max_tr_ring_buffer, global_max_buffer, trace_buffer, buffer);
>  	} else {
> @@ -528,6 +537,9 @@ static int ftrace_init(void)
>  
>  	if (MEMBER_EXISTS("trace_array", "trace_buffer")) {
>  		trace_buffer_available = 1;
> +
> +		if (MEMBER_EXISTS("trace_array", "max_buffer"))
> +			max_buffer_available = 1;
>  	} else {
>  		sym_max_tr_trace = symbol_search("max_tr");
>  		if (sym_max_tr_trace == NULL)
> --
> 1.7.10.4
> 
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