Hi Tom,
On Fri, 22 Mar 2019 10:34:27 -0500
Tom Zanussi <zanussi@xxxxxxxxxx> wrote:
> +static int tracing_err_log_open(struct inode *inode, struct file *file)
> +{
> + if (file->f_mode & FMODE_WRITE) {
> + if (file->f_flags & O_TRUNC)
> + return 0;
> + else
> + return -EINVAL;
> + }
> +
> + return seq_open(file, &tracing_err_log_seq_ops);
> +}
> +
> +static ssize_t tracing_err_log_write(struct file *file,
> + const char __user *buffer,
> + size_t count, loff_t *ppos)
> +{
> + if (count == 1)
> + clear_tracing_err_log();
> + else
> + return -EINVAL;
> +
> + *ppos += count;
> +
> + return count;
> +}
Hmm, could you make this as same as "tracing/trace"?
- It clears buffer at open with WRITE & TRUNC flag
- It just ignore how much user wrote (works as /dev/null)
See tracing_open() and tracing_write_stub() in
kernel/trace/trace.c.
Thank you,
> +
> +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;
> @@ -8258,6 +8478,9 @@ 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
> --
> 2.14.1
>
--
Masami Hiramatsu <mhiramat@xxxxxxxxxx>
