| Message ID | 20230111145842.376427803@goodmis.org (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | tracing: Addition of tracing instances via kernel command line | expand |
On 1/11/23 06:56, Steven Rostedt wrote: > From: "Steven Rostedt (Google)" <rostedt@goodmis.org> > > Add kernel command line to add tracing instances. This only creates > instances at boot but still does not enable any events to them. Later > changes will extend this command line to add enabling of events, filters, > and triggers. As well as possibly redirecting trace_printk()! > > Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> > --- > .../admin-guide/kernel-parameters.txt | 6 +++ > kernel/trace/trace.c | 51 +++++++++++++++++++ > 2 files changed, 57 insertions(+) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index 6cfa6e3996cf..cec486217ccc 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -6272,6 +6272,12 @@ > comma-separated list of trace events to enable. See > also Documentation/trace/events.rst > > + trace_instance=[instance-info] > + [FTRACE] Create an ring buffer instance early in boot up. s/an/a/ > + This will be listed in: > + > + /sys/kernel/tracing/instances > + > trace_options=[option-list] > [FTRACE] Enable or disable tracer options at boot. > The option-list is a comma delimited list of options
On Wed, Jan 11, 2023 at 09:56:37AM -0500, Steven Rostedt wrote: > From: "Steven Rostedt (Google)" <rostedt@goodmis.org> > > Add kernel command line to add tracing instances. This only creates > instances at boot but still does not enable any events to them. Later > changes will extend this command line to add enabling of events, filters, > and triggers. As well as possibly redirecting trace_printk()! > > Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> > --- > .../admin-guide/kernel-parameters.txt | 6 +++ > kernel/trace/trace.c | 51 +++++++++++++++++++ > 2 files changed, 57 insertions(+) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index 6cfa6e3996cf..cec486217ccc 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -6272,6 +6272,12 @@ > comma-separated list of trace events to enable. See > also Documentation/trace/events.rst > > + trace_instance=[instance-info] > + [FTRACE] Create an ring buffer instance early in boot up. > + This will be listed in: > + > + /sys/kernel/tracing/instances Should this be "/sys/kernel/debug/tracing/instances"? Ditto for the text for 'ftrace_boot_snapshot': ftrace_boot_snapshot [FTRACE] On boot up, a snapshot will be taken of the ftrace ring buffer that can be read at: /sys/kernel/tracing/snapshot. Everywhere else we use /sys/kernel/debug/tracing, though we do use /sys/kernel/tracing in Documentation/trace/ftrace.txt ? I guess either works, but having just 1 or the other will help us not confuse users. > + > trace_options=[option-list] > [FTRACE] Enable or disable tracer options at boot. > The option-list is a comma delimited list of options > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c > index a555a861b978..34ed504ffca9 100644 > --- a/kernel/trace/trace.c > +++ b/kernel/trace/trace.c > @@ -48,6 +48,9 @@ > #include <linux/fsnotify.h> > #include <linux/irq_work.h> > #include <linux/workqueue.h> > +#include <linux/workqueue.h> Duplicate include 1 line above. > + > +#include <asm/setup.h> /* COMMAND_LINE_SIZE */ > > #include "trace.h" > #include "trace_output.h" > @@ -186,6 +189,9 @@ static char *default_bootup_tracer; > static bool allocate_snapshot; > static bool snapshot_at_boot; > > +static char boot_instance_info[COMMAND_LINE_SIZE] __initdata; > +static int boot_instance_index; > + > static int __init set_cmdline_ftrace(char *str) > { > strlcpy(bootup_tracer_buf, str, MAX_TRACER_SIZE); > @@ -239,6 +245,23 @@ static int __init boot_snapshot(char *str) > __setup("ftrace_boot_snapshot", boot_snapshot); > > > +static int __init boot_instance(char *str) > +{ > + char *slot = boot_instance_info + boot_instance_index; > + int left = COMMAND_LINE_SIZE - boot_instance_index; A bit safer to use sizeof(boot_instance_info) instead of COMMAND_LINE_SIZE, so we can change the allocation size of boot_instance_info without having to keep them in sync. These are mostly nits, you can add: Reviewed-by: Ross Zwisler <zwisler@google.com>
On Thu, 12 Jan 2023 16:24:17 -0700 Ross Zwisler <zwisler@google.com> wrote: > On Wed, Jan 11, 2023 at 09:56:37AM -0500, Steven Rostedt wrote: > > From: "Steven Rostedt (Google)" <rostedt@goodmis.org> > > > > Add kernel command line to add tracing instances. This only creates > > instances at boot but still does not enable any events to them. Later > > changes will extend this command line to add enabling of events, filters, > > and triggers. As well as possibly redirecting trace_printk()! > > > > Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> > > --- > > .../admin-guide/kernel-parameters.txt | 6 +++ > > kernel/trace/trace.c | 51 +++++++++++++++++++ > > 2 files changed, 57 insertions(+) > > > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > > index 6cfa6e3996cf..cec486217ccc 100644 > > --- a/Documentation/admin-guide/kernel-parameters.txt > > +++ b/Documentation/admin-guide/kernel-parameters.txt > > @@ -6272,6 +6272,12 @@ > > comma-separated list of trace events to enable. See > > also Documentation/trace/events.rst > > > > + trace_instance=[instance-info] > > + [FTRACE] Create an ring buffer instance early in boot up. > > + This will be listed in: > > + > > + /sys/kernel/tracing/instances > > Should this be "/sys/kernel/debug/tracing/instances"? No, the /sys/kernel/debug/tracing is deprecated. It only exists for backward compatibility. If it's still in documentation, it should be updated. > > Ditto for the text for 'ftrace_boot_snapshot': > > ftrace_boot_snapshot > [FTRACE] On boot up, a snapshot will be taken of the > ftrace ring buffer that can be read at: > /sys/kernel/tracing/snapshot. > > Everywhere else we use /sys/kernel/debug/tracing, though we do use > /sys/kernel/tracing in Documentation/trace/ftrace.txt ? Right, that's because it was missed when I was updating it ;-) All documentation that references /sys/kernel/debug/tracing should be replaced with /sys/kernel/tracing. > > I guess either works, but having just 1 or the other will help us not confuse > users. Agreed. Want to send a clean up patch? ;-) > > > + > > trace_options=[option-list] > > [FTRACE] Enable or disable tracer options at boot. > > The option-list is a comma delimited list of options > > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c > > index a555a861b978..34ed504ffca9 100644 > > --- a/kernel/trace/trace.c > > +++ b/kernel/trace/trace.c > > @@ -48,6 +48,9 @@ > > #include <linux/fsnotify.h> > > #include <linux/irq_work.h> > > #include <linux/workqueue.h> > > +#include <linux/workqueue.h> > > Duplicate include 1 line above. Good catch. > > > + > > +#include <asm/setup.h> /* COMMAND_LINE_SIZE */ > > > > #include "trace.h" > > #include "trace_output.h" > > @@ -186,6 +189,9 @@ static char *default_bootup_tracer; > > static bool allocate_snapshot; > > static bool snapshot_at_boot; > > > > +static char boot_instance_info[COMMAND_LINE_SIZE] __initdata; > > +static int boot_instance_index; > > + > > static int __init set_cmdline_ftrace(char *str) > > { > > strlcpy(bootup_tracer_buf, str, MAX_TRACER_SIZE); > > @@ -239,6 +245,23 @@ static int __init boot_snapshot(char *str) > > __setup("ftrace_boot_snapshot", boot_snapshot); > > > > > > +static int __init boot_instance(char *str) > > +{ > > + char *slot = boot_instance_info + boot_instance_index; > > + int left = COMMAND_LINE_SIZE - boot_instance_index; > > A bit safer to use sizeof(boot_instance_info) instead of COMMAND_LINE_SIZE, > so we can change the allocation size of boot_instance_info without having to > keep them in sync. Either way is fine. I wouldn't make this change if it was the only thing I needed to fix, but as I need to get rid of the extra "workqueue.h", I can make this change too. > > These are mostly nits, you can add: > > Reviewed-by: Ross Zwisler <zwisler@google.com> Thanks! -- Steve
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 6cfa6e3996cf..cec486217ccc 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -6272,6 +6272,12 @@ comma-separated list of trace events to enable. See also Documentation/trace/events.rst + trace_instance=[instance-info] + [FTRACE] Create an ring buffer instance early in boot up. + This will be listed in: + + /sys/kernel/tracing/instances + trace_options=[option-list] [FTRACE] Enable or disable tracer options at boot. The option-list is a comma delimited list of options diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index a555a861b978..34ed504ffca9 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -48,6 +48,9 @@ #include <linux/fsnotify.h> #include <linux/irq_work.h> #include <linux/workqueue.h> +#include <linux/workqueue.h> + +#include <asm/setup.h> /* COMMAND_LINE_SIZE */ #include "trace.h" #include "trace_output.h" @@ -186,6 +189,9 @@ static char *default_bootup_tracer; static bool allocate_snapshot; static bool snapshot_at_boot; +static char boot_instance_info[COMMAND_LINE_SIZE] __initdata; +static int boot_instance_index; + static int __init set_cmdline_ftrace(char *str) { strlcpy(bootup_tracer_buf, str, MAX_TRACER_SIZE); @@ -239,6 +245,23 @@ static int __init boot_snapshot(char *str) __setup("ftrace_boot_snapshot", boot_snapshot); +static int __init boot_instance(char *str) +{ + char *slot = boot_instance_info + boot_instance_index; + int left = COMMAND_LINE_SIZE - boot_instance_index; + int ret; + + if (strlen(str) >= left) + return -1; + + ret = snprintf(slot, left, "%s\t", str); + boot_instance_index += ret; + + return 1; +} +__setup("trace_instance=", boot_instance); + + static char trace_boot_options_buf[MAX_TRACER_SIZE] __initdata; static int __init set_trace_boot_options(char *str) @@ -10144,6 +10167,31 @@ ssize_t trace_parse_run_command(struct file *file, const char __user *buffer, return ret; } +__init static void enable_instances(void) +{ + struct trace_array *tr; + char *curr_str; + char *str; + char *tok; + + /* A tab is always appended */ + boot_instance_info[boot_instance_index - 1] = '\0'; + str = boot_instance_info; + + while ((curr_str = strsep(&str, "\t"))) { + + tok = strsep(&curr_str, ","); + + tr = trace_array_get_by_name(tok); + if (!tr) { + pr_warn("Failed to create instance buffer %s\n", curr_str); + continue; + } + /* Allow user space to delete it */ + trace_array_put(tr); + } +} + __init static int tracer_alloc_buffers(void) { int ring_buf_size; @@ -10300,6 +10348,9 @@ void __init early_trace_init(void) void __init trace_init(void) { trace_event_init(); + + if (boot_instance_index) + enable_instances(); } __init static void clear_boot_tracer(void)