Messages in this thread Patch in this message | | | Date | Wed, 11 Jan 2023 09:56:40 -0500 | From | Steven Rostedt <> | Subject | [PATCH 4/4] tracing: Allow boot instances to have snapshot buffers |
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From: "Steven Rostedt (Google)" <rostedt@goodmis.org>
Add to ftrace_boot_snapshot, "=<instance>" name, where the instance will get a snapshot buffer, and will take a snapshot at the end of boot (which will save the boot traces).
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> --- .../admin-guide/kernel-parameters.txt | 9 +++ kernel/trace/trace.c | 77 +++++++++++++++++-- 2 files changed, 79 insertions(+), 7 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 7a7f41652719..f4e87b17427f 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -1532,6 +1532,15 @@ boot up that is likely to be overridden by user space start up functionality. + Optionally, the snapshot can also be defined for a tracing + instance that was created by the trace_instance= command + line parameter. + + trace_instance=foo,sched_switch ftrace_boot_snapshot=foo + + The above will cause the "foo" tracing instance to trigger + a snapshot at the end of boot up. + ftrace_dump_on_oops[=orig_cpu] [FTRACE] will dump the trace buffers on oops. If no parameter is passed, ftrace will dump diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 3cb9bbc0f076..d445789dc247 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -192,6 +192,9 @@ static bool snapshot_at_boot; static char boot_instance_info[COMMAND_LINE_SIZE] __initdata; static int boot_instance_index; +static char boot_snapshot_info[COMMAND_LINE_SIZE] __initdata; +static int boot_snapshot_index; + static int __init set_cmdline_ftrace(char *str) { strlcpy(bootup_tracer_buf, str, MAX_TRACER_SIZE); @@ -228,9 +231,22 @@ __setup("traceoff_on_warning", stop_trace_on_warning); static int __init boot_alloc_snapshot(char *str) { - allocate_snapshot = true; - /* We also need the main ring buffer expanded */ - ring_buffer_expanded = true; + char *slot = boot_snapshot_info + boot_snapshot_index; + int left = COMMAND_LINE_SIZE - boot_snapshot_index; + int ret; + + if (str[0] == '=') { + str++; + if (strlen(str) >= left) + return -1; + + ret = snprintf(slot, left, "%s\t", str); + boot_snapshot_index += ret; + } else { + allocate_snapshot = true; + /* We also need the main ring buffer expanded */ + ring_buffer_expanded = true; + } return 1; } __setup("alloc_snapshot", boot_alloc_snapshot); @@ -9255,10 +9271,6 @@ static int allocate_trace_buffers(struct trace_array *tr, int size) } tr->allocated_snapshot = allocate_snapshot; - /* - * Only the top level trace array gets its snapshot allocated - * from the kernel command line. - */ allocate_snapshot = false; #endif @@ -10174,6 +10186,45 @@ ssize_t trace_parse_run_command(struct file *file, const char __user *buffer, return ret; } +#ifdef CONFIG_TRACER_MAX_TRACE +__init static bool tr_needs_alloc_snapshot(const char *name) +{ + char *test; + int len = strlen(name); + bool ret; + + if (!boot_snapshot_index) + return false; + + if (strncmp(name, boot_snapshot_info, len) == 0 && + boot_snapshot_info[len] == '\t') + return true; + + test = kmalloc(strlen(name) + 3, GFP_KERNEL); + if (!test) + return false; + + sprintf(test, "\t%s\t", name); + ret = strstr(boot_snapshot_info, test) == 0; + kfree(test); + return ret; +} + +__init static void do_allocate_snapshot(const char *name) +{ + if (!tr_needs_alloc_snapshot(name)) + return; + + /* + * When allocate_snapshot is set, the next call to + * allocate_trace_buffers() (called by trace_array_get_by_name()) + * will allocate the snapshot buffer. That will alse clear + * this flag. + */ + allocate_snapshot = true; +} +#endif + __init static void enable_instances(void) { struct trace_array *tr; @@ -10189,6 +10240,9 @@ __init static void enable_instances(void) tok = strsep(&curr_str, ","); + if (IS_ENABLED(CONFIG_TRACER_MAX_TRACE)) + do_allocate_snapshot(tok); + tr = trace_array_get_by_name(tok); if (!tr) { pr_warn("Failed to create instance buffer %s\n", curr_str); @@ -10336,10 +10390,19 @@ __init static int tracer_alloc_buffers(void) void __init ftrace_boot_snapshot(void) { + struct trace_array *tr; + if (snapshot_at_boot) { tracing_snapshot(); internal_trace_puts("** Boot snapshot taken **\n"); } + + list_for_each_entry(tr, &ftrace_trace_arrays, list) { + if (tr == &global_trace) + continue; + trace_array_puts(tr, "** Boot snapshot taken **\n"); + tracing_snapshot_instance(tr); + } } void __init early_trace_init(void) -- 2.39.0
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