| Message ID | 20220323152257.7871-2-mark-pk.tsai@mediatek.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | tracing: make tracer_init_tracefs initcall asynchronous | expand |
On Wed, 23 Mar 2022 23:22:56 +0800 Mark-PK Tsai <mark-pk.tsai@mediatek.com> wrote: > To prepare for support asynchronous tracer_init_tracefs initcall, > avoid calling create_trace_option_files before __update_tracer_options. > Otherwise, create_trace_option_files will show warning because > some tracers in trace_types list are already in tr->topts. > > For example, hwlat_tracer call register_tracer in late_initcall, > and global_trace.dir is already created in tracing_init_dentry, > hwlat_tracer will be put into tr->topts. > Then if the __update_tracer_options is executed after hwlat_tracer > registered, create_trace_option_files find that hwlat_tracer is > already in tr->topts. > > Link: https://lore.kernel.org/lkml/20220322133339.GA32582@xsang-OptiPlex-9020/ > Reported-by: kernel test robot <oliver.sang@intel.com> > Signed-off-by: Mark-PK Tsai <mark-pk.tsai@mediatek.com> Before this patch: # ls /sys/kernel/tracing/options annotate funcgraph-duration hex stacktrace bin funcgraph-irqs irq-info sym-addr blk_cgname funcgraph-overhead latency-format sym-offset blk_cgroup funcgraph-overrun markers sym-userobj blk_classic funcgraph-proc overwrite test_nop_accept block funcgraph-tail pause-on-trace test_nop_refuse context-info func-no-repeats printk-msg-only trace_printk disable_on_free func_stack_trace print-parent userstacktrace display-graph function-fork raw verbose event-fork function-trace record-cmd funcgraph-abstime graph-time record-tgid funcgraph-cpu hash-ptr sleep-time After this patch: # ls /sys/kernel/tracing/options annotate disable_on_free irq-info raw trace_printk bin display-graph latency-format record-cmd userstacktrace blk_cgname event-fork markers record-tgid verbose blk_cgroup function-fork overwrite stacktrace blk_classic function-trace pause-on-trace sym-addr block hash-ptr printk-msg-only sym-offset context-info hex print-parent sym-userobj Not good. > --- > kernel/trace/trace.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c > index eb44418574f9..85ec758c4455 100644 > --- a/kernel/trace/trace.c > +++ b/kernel/trace/trace.c > @@ -6317,12 +6317,18 @@ static void tracing_set_nop(struct trace_array *tr) > tr->current_trace = &nop_trace; > } > > +static bool tracer_options_updated; > + > static void add_tracer_options(struct trace_array *tr, struct tracer *t) > { > /* Only enable if the directory has been created already. */ > if (!tr->dir) > return; > > + /* Only create trace option files after update_tracer_options finish */ > + if (!tracer_options_updated) > + return; > + > create_trace_option_files(tr, t); > } > > @@ -9133,6 +9139,7 @@ static void update_tracer_options(struct trace_array *tr) > { > mutex_lock(&trace_types_lock); > __update_tracer_options(tr); > + tracer_options_updated = true; I think you want to set this before the __update, as doing it after just makes the update a nop. -- Steve > mutex_unlock(&trace_types_lock); > } >
> > To prepare for support asynchronous tracer_init_tracefs initcall, > > avoid calling create_trace_option_files before __update_tracer_options. > > Otherwise, create_trace_option_files will show warning because > > some tracers in trace_types list are already in tr->topts. > > > > For example, hwlat_tracer call register_tracer in late_initcall, > > and global_trace.dir is already created in tracing_init_dentry, > > hwlat_tracer will be put into tr->topts. > > Then if the __update_tracer_options is executed after hwlat_tracer > > registered, create_trace_option_files find that hwlat_tracer is > > already in tr->topts. > > > > Link: https://lore.kernel.org/lkml/20220322133339.GA32582@xsang-OptiPlex-9020/ > > Reported-by: kernel test robot <oliver.sang@intel.com> > > Signed-off-by: Mark-PK Tsai <mark-pk.tsai@mediatek.com> > > Before this patch: > > # ls /sys/kernel/tracing/options > annotate funcgraph-duration hex stacktrace > bin funcgraph-irqs irq-info sym-addr > blk_cgname funcgraph-overhead latency-format sym-offset > blk_cgroup funcgraph-overrun markers sym-userobj > blk_classic funcgraph-proc overwrite test_nop_accept > block funcgraph-tail pause-on-trace test_nop_refuse > context-info func-no-repeats printk-msg-only trace_printk > disable_on_free func_stack_trace print-parent userstacktrace > display-graph function-fork raw verbose > event-fork function-trace record-cmd > funcgraph-abstime graph-time record-tgid > funcgraph-cpu hash-ptr sleep-time > > > After this patch: > > # ls /sys/kernel/tracing/options > annotate disable_on_free irq-info raw trace_printk > bin display-graph latency-format record-cmd userstacktrace > blk_cgname event-fork markers record-tgid verbose > blk_cgroup function-fork overwrite stacktrace > blk_classic function-trace pause-on-trace sym-addr > block hash-ptr printk-msg-only sym-offset > context-info hex print-parent sym-userobj > > Not good. Calling __update_tracer_options() when tracer_options_updated=false have no effect because it return directly in add_tracer_options(). I will fix it in v4 as you suggest in the below comment. > > > --- > > kernel/trace/trace.c | 7 +++++++ > > 1 file changed, 7 insertions(+) > > > > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c > > index eb44418574f9..85ec758c4455 100644 > > --- a/kernel/trace/trace.c > > +++ b/kernel/trace/trace.c > > @@ -6317,12 +6317,18 @@ static void tracing_set_nop(struct trace_array *tr) > > tr->current_trace = &nop_trace; > > } > > > > +static bool tracer_options_updated; > > + > > static void add_tracer_options(struct trace_array *tr, struct tracer *t) > > { > > /* Only enable if the directory has been created already. */ > > if (!tr->dir) > > return; > > > > + /* Only create trace option files after update_tracer_options finish */ > > + if (!tracer_options_updated) > > + return; > > + > > create_trace_option_files(tr, t); > > } > > > > @@ -9133,6 +9139,7 @@ static void update_tracer_options(struct trace_array *tr) > > { > > mutex_lock(&trace_types_lock); > > __update_tracer_options(tr); > > + tracer_options_updated = true; > > I think you want to set this before the __update, as doing it after just > makes the update a nop. You are right. I will update in v4, thanks! > > -- Steve > > > > mutex_unlock(&trace_types_lock); > > } > >
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index eb44418574f9..85ec758c4455 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -6317,12 +6317,18 @@ static void tracing_set_nop(struct trace_array *tr) tr->current_trace = &nop_trace; } +static bool tracer_options_updated; + static void add_tracer_options(struct trace_array *tr, struct tracer *t) { /* Only enable if the directory has been created already. */ if (!tr->dir) return; + /* Only create trace option files after update_tracer_options finish */ + if (!tracer_options_updated) + return; + create_trace_option_files(tr, t); } @@ -9133,6 +9139,7 @@ static void update_tracer_options(struct trace_array *tr) { mutex_lock(&trace_types_lock); __update_tracer_options(tr); + tracer_options_updated = true; mutex_unlock(&trace_types_lock); }
To prepare for support asynchronous tracer_init_tracefs initcall, avoid calling create_trace_option_files before __update_tracer_options. Otherwise, create_trace_option_files will show warning because some tracers in trace_types list are already in tr->topts. For example, hwlat_tracer call register_tracer in late_initcall, and global_trace.dir is already created in tracing_init_dentry, hwlat_tracer will be put into tr->topts. Then if the __update_tracer_options is executed after hwlat_tracer registered, create_trace_option_files find that hwlat_tracer is already in tr->topts. Link: https://lore.kernel.org/lkml/20220322133339.GA32582@xsang-OptiPlex-9020/ Reported-by: kernel test robot <oliver.sang@intel.com> Signed-off-by: Mark-PK Tsai <mark-pk.tsai@mediatek.com> --- kernel/trace/trace.c | 7 +++++++ 1 file changed, 7 insertions(+)