diff options
| -rw-r--r-- | kernel/trace/trace.c | 218 | ||||
| -rw-r--r-- | kernel/trace/trace.h | 4 |
2 files changed, 222 insertions, 0 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 4384fcc386c8..7978168f5041 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -6878,6 +6878,221 @@ static const struct file_operations snapshot_raw_fops = { #endif /* CONFIG_TRACER_SNAPSHOT */ +#define TRACING_LOG_ERRS_MAX 8 +#define TRACING_LOG_LOC_MAX 128 + +#define CMD_PREFIX " Command: " + +struct err_info { + const char **errs; /* ptr to loc-specific array of err strings */ + u8 type; /* index into errs -> specific err string */ + u8 pos; /* MAX_FILTER_STR_VAL = 256 */ + u64 ts; +}; + +struct tracing_log_err { + struct list_head list; + struct err_info info; + char loc[TRACING_LOG_LOC_MAX]; /* err location */ + char cmd[MAX_FILTER_STR_VAL]; /* what caused err */ +}; + +static LIST_HEAD(tracing_err_log); +static DEFINE_MUTEX(tracing_err_log_lock); + +static unsigned int n_tracing_err_log_entries; + +struct tracing_log_err *get_tracing_log_err(void) +{ + struct tracing_log_err *err; + + if (n_tracing_err_log_entries < TRACING_LOG_ERRS_MAX) { + err = kzalloc(sizeof(*err), GFP_KERNEL); + if (!err) + err = ERR_PTR(-ENOMEM); + n_tracing_err_log_entries++; + + return err; + } + + err = list_first_entry(&tracing_err_log, struct tracing_log_err, list); + list_del(&err->list); + + return err; +} + +/** + * err_pos - find the position of a string within a command for error careting + * @cmd: The tracing command that caused the error + * @str: The string to position the caret at within @cmd + * + * Finds the position of the first occurence of @str within @cmd. The + * return value can be passed to tracing_log_err() for caret placement + * within @cmd. + * + * Returns the index within @cmd of the first occurence of @str or 0 + * if @str was not found. + */ +unsigned int err_pos(char *cmd, const char *str) +{ + char *found; + + if (WARN_ON(!strlen(cmd))) + return 0; + + found = strstr(cmd, str); + if (found) + return found - cmd; + + return 0; +} + +/** + * tracing_log_err - write an error to the tracing error log + * @loc: A string describing where the error occurred + * @cmd: The tracing command that caused the error + * @errs: The array of loc-specific static error strings + * @type: The index into errs[], which produces the specific static err string + * @pos: The position the caret should be placed in the cmd + * + * Writes an error into tracing/error_log of the form: + * + * <loc>: error: <text> + * Command: <cmd> + * ^ + * + * tracing/error_log is a small log file containing the last + * TRACING_LOG_ERRS_MAX errors (8). Memory for errors isn't allocated + * unless there has been a tracing error, and the error log can be + * cleared and have its memory freed by writing the empty string in + * truncation mode to it i.e. echo > tracing/error_log. + * + * NOTE: the @errs array along with the @type param are used to + * produce a static error string - this string is not copied and saved + * when the error is logged - only a pointer to it is saved. See + * existing callers for examples of how static strings are typically + * defined for use with tracing_log_err(). + */ +void tracing_log_err(const char *loc, const char *cmd, + const char **errs, u8 type, u8 pos) +{ + struct tracing_log_err *err; + + mutex_lock(&tracing_err_log_lock); + err = get_tracing_log_err(); + if (PTR_ERR(err) == -ENOMEM) { + mutex_unlock(&tracing_err_log_lock); + return; + } + + snprintf(err->loc, TRACING_LOG_LOC_MAX, "%s: error: ", loc); + snprintf(err->cmd, MAX_FILTER_STR_VAL,"\n" CMD_PREFIX "%s\n", cmd); + + err->info.errs = errs; + err->info.type = type; + err->info.pos = pos; + err->info.ts = local_clock(); + + list_add_tail(&err->list, &tracing_err_log); + mutex_unlock(&tracing_err_log_lock); +} + +static void clear_tracing_err_log(void) +{ + struct tracing_log_err *err, *next; + + mutex_lock(&tracing_err_log_lock); + list_for_each_entry_safe(err, next, &tracing_err_log, list) { + list_del(&err->list); + kfree(err); + } + + n_tracing_err_log_entries = 0; + mutex_unlock(&tracing_err_log_lock); +} + +static void *tracing_err_log_seq_start(struct seq_file *m, loff_t *pos) +{ + mutex_lock(&tracing_err_log_lock); + + return seq_list_start(&tracing_err_log, *pos); +} + +static void *tracing_err_log_seq_next(struct seq_file *m, void *v, loff_t *pos) +{ + return seq_list_next(v, &tracing_err_log, pos); +} + +static void tracing_err_log_seq_stop(struct seq_file *m, void *v) +{ + mutex_unlock(&tracing_err_log_lock); +} + +static void tracing_err_log_show_pos(struct seq_file *m, u8 pos) +{ + u8 i; + + for (i = 0; i < sizeof(CMD_PREFIX) - 1; i++) + seq_putc(m, ' '); + for (i = 0; i < pos; i++) + seq_putc(m, ' '); + seq_puts(m, "^\n"); +} + +static int tracing_err_log_seq_show(struct seq_file *m, void *v) +{ + struct tracing_log_err *err = v; + + if (err) { + const char *err_text = err->info.errs[err->info.type]; + u64 sec = err->info.ts; + u32 nsec; + + nsec = do_div(sec, NSEC_PER_SEC); + seq_printf(m, "[%5llu.%06u] %s%s", sec, nsec / 1000, + err->loc, err_text); + seq_printf(m, "%s", err->cmd); + tracing_err_log_show_pos(m, err->info.pos); + } + + return 0; +} + +static const struct seq_operations tracing_err_log_seq_ops = { + .start = tracing_err_log_seq_start, + .next = tracing_err_log_seq_next, + .stop = tracing_err_log_seq_stop, + .show = tracing_err_log_seq_show +}; + +static int tracing_err_log_open(struct inode *inode, struct file *file) +{ + int ret = 0; + + /* If this file was opened for write, then erase contents */ + if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC)) + clear_tracing_err_log(); + + if (file->f_mode & FMODE_READ) + ret = seq_open(file, &tracing_err_log_seq_ops); + + return ret; +} + +static ssize_t tracing_err_log_write(struct file *file, + const char __user *buffer, + size_t count, loff_t *ppos) +{ + return count; +} + +static const struct file_operations tracing_err_log_fops = { + .open = tracing_err_log_open, + .write = tracing_err_log_write, + .read = seq_read, + .llseek = seq_lseek, +}; + static int tracing_buffers_open(struct inode *inode, struct file *filp) { struct trace_array *tr = inode->i_private; @@ -8284,6 +8499,9 @@ init_tracer_tracefs(struct trace_array *tr, struct dentry *d_tracer) tr, &snapshot_fops); #endif + trace_create_file("error_log", 0644, d_tracer, + tr, &tracing_err_log_fops); + for_each_tracing_cpu(cpu) tracing_init_tracefs_percpu(tr, cpu); diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index d80cee49e0eb..b711edbef7e7 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -1884,6 +1884,10 @@ extern ssize_t trace_parse_run_command(struct file *file, const char __user *buffer, size_t count, loff_t *ppos, int (*createfn)(int, char**)); +extern unsigned int err_pos(char *cmd, const char *str); +extern void tracing_log_err(const char *loc, const char *cmd, + const char **errs, u8 type, u8 pos); + /* * Normal trace_printk() and friends allocates special buffers * to do the manipulation, as well as saves the print formats |