From b179d48b6aab21f3999f5006685ea4254c0618a9 Mon Sep 17 00:00:00 2001 From: Daniel Bristot de Oliveira Date: Thu, 17 Nov 2022 14:46:18 +0100 Subject: [PATCH] tracing/osnoise: Add osnoise/options file Add the tracing/osnoise/options file to control osnoise/timerlat tracer features. It is a single file to contain multiple features, similar to the sched/features file. Reading the file displays a list of options. Writing the OPTION_NAME enables it, writing NO_OPTION_NAME disables it. The DEAFULTS is a particular option that resets the options to the default ones. It uses a bitmask to keep track of the status of the option. When needed, we can add a list of static keys, but for now it does not justify the memory increase. Link: https://lkml.kernel.org/r/f8d34aefdb225d2603fcb4c02a120832a0cd3339.1668692096.git.bristot@kernel.org Cc: Daniel Bristot de Oliveira Cc: Masami Hiramatsu Cc: Jonathan Corbet Signed-off-by: Daniel Bristot de Oliveira Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace_osnoise.c | 170 +++++++++++++++++++++++++++++++++++ 1 file changed, 170 insertions(+) diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c index 4300c5dc4e5d..17b77fe3950b 100644 --- a/kernel/trace/trace_osnoise.c +++ b/kernel/trace/trace_osnoise.c @@ -48,6 +48,19 @@ #define DEFAULT_TIMERLAT_PERIOD 1000 /* 1ms */ #define DEFAULT_TIMERLAT_PRIO 95 /* FIFO 95 */ +/* + * osnoise/options entries. + */ +enum osnoise_options_index { + OSN_DEFAULTS = 0, + OSN_MAX +}; + +static const char * const osnoise_options_str[OSN_MAX] = { "DEFAULTS" }; + +#define OSN_DEFAULT_OPTIONS 0 +unsigned long osnoise_options = OSN_DEFAULT_OPTIONS; + /* * trace_array of the enabled osnoise/timerlat instances. */ @@ -1860,6 +1873,150 @@ static void osnoise_init_hotplug_support(void) } #endif /* CONFIG_HOTPLUG_CPU */ +/* + * seq file functions for the osnoise/options file. + */ +static void *s_options_start(struct seq_file *s, loff_t *pos) +{ + int option = *pos; + + mutex_lock(&interface_lock); + + if (option >= OSN_MAX) + return NULL; + + return pos; +} + +static void *s_options_next(struct seq_file *s, void *v, loff_t *pos) +{ + int option = ++(*pos); + + if (option >= OSN_MAX) + return NULL; + + return pos; +} + +static int s_options_show(struct seq_file *s, void *v) +{ + loff_t *pos = v; + int option = *pos; + + if (option == OSN_DEFAULTS) { + if (osnoise_options == OSN_DEFAULT_OPTIONS) + seq_printf(s, "%s", osnoise_options_str[option]); + else + seq_printf(s, "NO_%s", osnoise_options_str[option]); + goto out; + } + + if (test_bit(option, &osnoise_options)) + seq_printf(s, "%s", osnoise_options_str[option]); + else + seq_printf(s, "NO_%s", osnoise_options_str[option]); + +out: + if (option != OSN_MAX) + seq_puts(s, " "); + + return 0; +} + +static void s_options_stop(struct seq_file *s, void *v) +{ + seq_puts(s, "\n"); + mutex_unlock(&interface_lock); +} + +static const struct seq_operations osnoise_options_seq_ops = { + .start = s_options_start, + .next = s_options_next, + .show = s_options_show, + .stop = s_options_stop +}; + +static int osnoise_options_open(struct inode *inode, struct file *file) +{ + return seq_open(file, &osnoise_options_seq_ops); +}; + +/** + * osnoise_options_write - Write function for "options" entry + * @filp: The active open file structure + * @ubuf: The user buffer that contains the value to write + * @cnt: The maximum number of bytes to write to "file" + * @ppos: The current position in @file + * + * Writing the option name sets the option, writing the "NO_" + * prefix in front of the option name disables it. + * + * Writing "DEFAULTS" resets the option values to the default ones. + */ +static ssize_t osnoise_options_write(struct file *filp, const char __user *ubuf, + size_t cnt, loff_t *ppos) +{ + int running, option, enable, retval; + char buf[256], *option_str; + + if (cnt >= 256) + return -EINVAL; + + if (copy_from_user(buf, ubuf, cnt)) + return -EFAULT; + + buf[cnt] = 0; + + if (strncmp(buf, "NO_", 3)) { + option_str = strstrip(buf); + enable = true; + } else { + option_str = strstrip(&buf[3]); + enable = false; + } + + option = match_string(osnoise_options_str, OSN_MAX, option_str); + if (option < 0) + return -EINVAL; + + /* + * trace_types_lock is taken to avoid concurrency on start/stop. + */ + mutex_lock(&trace_types_lock); + running = osnoise_has_registered_instances(); + if (running) + stop_per_cpu_kthreads(); + + mutex_lock(&interface_lock); + /* + * avoid CPU hotplug operations that might read options. + */ + cpus_read_lock(); + + retval = cnt; + + if (enable) { + if (option == OSN_DEFAULTS) + osnoise_options = OSN_DEFAULT_OPTIONS; + else + set_bit(option, &osnoise_options); + } else { + if (option == OSN_DEFAULTS) + retval = -EINVAL; + else + clear_bit(option, &osnoise_options); + } + + cpus_read_unlock(); + mutex_unlock(&interface_lock); + + if (running) + start_per_cpu_kthreads(); + mutex_unlock(&trace_types_lock); + + return retval; +} + /* * osnoise_cpus_read - Read function for reading the "cpus" file * @filp: The active open file structure @@ -2042,6 +2199,14 @@ static const struct file_operations cpus_fops = { .llseek = generic_file_llseek, }; +static const struct file_operations osnoise_options_fops = { + .open = osnoise_options_open, + .read = seq_read, + .llseek = seq_lseek, + .release = seq_release, + .write = osnoise_options_write +}; + #ifdef CONFIG_TIMERLAT_TRACER #ifdef CONFIG_STACKTRACE static int init_timerlat_stack_tracefs(struct dentry *top_dir) @@ -2128,6 +2293,11 @@ static int init_tracefs(void) if (!tmp) goto err; + tmp = trace_create_file("options", TRACE_MODE_WRITE, top_dir, NULL, + &osnoise_options_fops); + if (!tmp) + goto err; + ret = init_timerlat_tracefs(top_dir); if (ret) goto err;