Messages in this thread |  | | Date | Tue, 31 Jan 2017 10:15:09 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH v2 2/4] perf ftrace: Add ftrace.tracer config option |
| |
Em Tue, Jan 31, 2017 at 09:46:28AM -0300, Arnaldo Carvalho de Melo escreveu: > Also you are silently ignoring any unknown variable in this section, so > if someone has this: > > cat ~/.perfconfig > > [ftrace] > > trace = function > > > I.e. forgets the 'r', it will keep using the current default, > "function_graph" till the user checks the config and adds that missing > 'r'... > > I haven't changed this because I think this is so common that we should > instead have a different error return for those config callbacks that > will tell perf_config() to say something like: > > "unknown variable %s.%s\n", section_name, variable_name
So I read a bit more the config code and ended up with this:
static int perf_ftrace_config(const char *var, const char *value, void *cb) { struct perf_ftrace *ftrace = cb;
if (prefixcmp(var, "ftrace.")) return 0;
if (strcmp(var, "ftrace.tracer")) return -1;
if (!strcmp(value, "function_graph") || !strcmp(value, "function")) { ftrace->tracer = value; return 0; }
pr_err("Please select \"function_graph\" (default) or \"function\"\n"); return -1; }
I.e. it will ignore variables for other sections and will stop at an unknown variable or value for ftrace.tracer:
[root@jouet ~]# cat ~/.perfconfig [ftrace] trace = function [root@jouet ~]# perf ftrace usleep 1 Error: wrong config key-value pair ftrace.trace=function [root@jouet ~]# cat ~/.perfconfig [ftrace] tracer = functin [root@jouet ~]# perf ftrace usleep 1 Please select "function_graph" (default) or "function" Error: wrong config key-value pair ftrace.tracer=functin [root@jouet ~]# cat ~/.perfconfig [ftrace] tracer = function [root@jouet ~]# perf ftrace usleep 1 | head -5 <idle>-0 [000] d... 3855.820847: switch_mm_irqs_off <-__schedule <...>-18550 [000] d... 3855.820849: finish_task_switch <-__schedule <...>-18550 [000] d... 3855.820851: smp_irq_work_interrupt <-irq_work_interrupt <...>-18550 [000] d... 3855.820851: irq_enter <-smp_irq_work_interrupt <...>-18550 [000] d... 3855.820851: rcu_irq_enter <-irq_enter [root@jouet ~]#
- Arnaldo
|  |