Re: [PATCH 2/2] tracing/irqsoff: Balance prolog on fgraph failure

[Steven Rostedt]

On Mon,  6 Oct 2025 13:58:48 -0400
Sasha Levin <sas...@kernel.org> wrote:

> diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c
> index 5496758b6c760..39152ef3d2432 100644
> --- a/kernel/trace/trace_irqsoff.c
> +++ b/kernel/trace/trace_irqsoff.c
> @@ -202,8 +202,10 @@ static int irqsoff_graph_entry(struct ftrace_graph_ent 
> *trace,
>               return 0;
>  
>       calltime = fgraph_reserve_data(gops->idx, sizeof(*calltime));
> -     if (!calltime)
> +     if (!calltime) {
> +             local_dec(&data->disabled);
>               return 0;
> +     }
>  
>       *calltime = trace_clock_local();
>  
> @@ -233,8 +235,10 @@ static void irqsoff_graph_return(struct ftrace_graph_ret 
> *trace,
>  
>       rettime = trace_clock_local();
>       calltime = fgraph_retrieve_data(gops->idx, &size);
> -     if (!calltime)
> +     if (!calltime) {
> +             local_dec(&data->disabled);
>               return;
> +     }
>  
>       trace_ctx = tracing_gen_ctx_flags(flags);
>       __trace_graph_return(tr, trace, trace_ctx, *calltime, rettime);
> -- 

Technically correct, but this would look better:

diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c
index 5496758b6c76..4c45c49b06c8 100644
--- a/kernel/trace/trace_irqsoff.c
+++ b/kernel/trace/trace_irqsoff.c
@@ -184,7 +184,7 @@ static int irqsoff_graph_entry(struct ftrace_graph_ent 
*trace,
        unsigned long flags;
        unsigned int trace_ctx;
        u64 *calltime;
-       int ret;
+       int ret = 0;
 
        if (ftrace_graph_ignore_func(gops, trace))
                return 0;
@@ -202,13 +202,11 @@ static int irqsoff_graph_entry(struct ftrace_graph_ent 
*trace,
                return 0;
 
        calltime = fgraph_reserve_data(gops->idx, sizeof(*calltime));
-       if (!calltime)
-               return 0;
-
-       *calltime = trace_clock_local();
-
-       trace_ctx = tracing_gen_ctx_flags(flags);
-       ret = __trace_graph_entry(tr, trace, trace_ctx);
+       if (calltime) {
+               *calltime = trace_clock_local();
+               trace_ctx = tracing_gen_ctx_flags(flags);
+               ret = __trace_graph_entry(tr, trace, trace_ctx);
+       }
        local_dec(&data->disabled);
 
        return ret;
@@ -233,11 +231,10 @@ static void irqsoff_graph_return(struct ftrace_graph_ret 
*trace,
 
        rettime = trace_clock_local();
        calltime = fgraph_retrieve_data(gops->idx, &size);
-       if (!calltime)
-               return;
-
-       trace_ctx = tracing_gen_ctx_flags(flags);
-       __trace_graph_return(tr, trace, trace_ctx, *calltime, rettime);
+       if (calltime) {
+               trace_ctx = tracing_gen_ctx_flags(flags);
+               __trace_graph_return(tr, trace, trace_ctx, *calltime, rettime);
+       }
        local_dec(&data->disabled);
 }
 
-- Steve