Re: [PATCH 5/5] blktrace: print human-readable act_mask

Steven Rostedt
2009-03-24T15:48:45Z

On Tue, 24 Mar 2009, Li Zefan wrote:
> +static ssize_t blk_trace_mask2str(char *buf, int mask)
> +{
> + int i;
> + char *p = buf;
> +
> + for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
> + if (mask & mask_maps[i].mask) {
> + p += sprintf(p, "%s%s",
> + (p == buf) ? "" : ",", mask_maps[i].str);
> + }
> + }
> + *p++ = '\n';
> +
> + return (p - buf);

The above is still simple, but if it starts to ge complex, you might want
to convert it to the trace_seq functions. That can make moving to a buffer
easier.

#include "trace_output.h"

static bool blk_trace_mask2str(struct trace_seq *s, int mask)
{
bool comma = false;
int i;

for (i = 0; i < ARRAY_SIZE(mask_maps); i++) {
if (mask & mask_maps[i].mask) {
trace_print_seq(s, "%s%s",
comma ? "," : "",
mask_maps[i].str);
comma = 1;
}
}
}

struct trace_seq *s;

s = kmalloc(sizeof(*s), GFP_KERNEL);
if (!s)
do error;

blk_trace_str2mask(s, mask);

This would put the data into s->buffer and have a length too.

Just letting you know about this. It may come in handy. Most of the code
in kernel/trace*.c uses this.

-- Steve

> +}
> +
> static struct request_queue *blk_trace_get_queue(struct block_device *bdev)
> {
> if (bdev->bd_disk == NULL)
> @@ -1399,7 +1423,7 @@ static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
> if (q->blk_trace == NULL)
> ret = sprintf(buf, "disabled\n");
> else if (attr == &dev_attr_act_mask)
> - ret = sprintf(buf, "%#x\n", q->blk_trace->act_mask);
> + ret = blk_trace_mask2str(buf, q->blk_trace->act_mask);
> else if (attr == &dev_attr_pid)
> ret = sprintf(buf, "%u\n", q->blk_trace->pid);
> else if (attr == &dev_attr_start_lba)
> @@ -1432,9 +1456,11 @@ static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
> if (attr == &dev_attr_act_mask) {
> if (sscanf(buf, "%llx", &value) != 1) {
> /* Assume it is a list of trace category names */
> - value = blk_str2act_mask(buf);
> - if (value < 0)
> + value = blk_trace_str2mask(buf);
> + if (value < 0) {
> + ret = value;
> goto out;
> + }
> }
> } else if (sscanf(buf, "%llu", &value) != 1)
> goto out;
> --
> 1.5.4.rc3
>
>