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SubjectRe: [PATCH] tools/lib/traceevent, perf tools: Handle %pU format correctly
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On 16.10.19 г. 9:39 ч., Qu Wenruo wrote:
> [BUG]
> For btrfs related events, there is a field for fsid, but perf never
> parse it correctly.
>
> # perf trace -e btrfS:qgroup_meta_convert xfs_io -f -c "pwrite 0 4k" \
> /mnt/btrfs/file1
> 0.000 xfs_io/77915 btrfs:qgroup_meta_reserve:(nil)U: refroot=5(FS_TREE) type=0x0 diff=2
> ^^^^^^ Not a correct UUID
> ...
>
> [CAUSE]
> The pretty_print() function doesn't handle the %pU format correctly.
> In fact it doesn't handle %pU as uuid at all.
>
> [FIX]
> Add a new functiono, print_uuid_arg(), to handle %pU correctly.
>
> Now perf trace can at least print fsid correctly:
> 0.000 xfs_io/79619 btrfs:qgroup_meta_reserve:23ad1511-dd83-47d4-a79c-e96625a15a6e refroot=5(FS_TREE) type=0x0 diff=2
>
> Signed-off-by: Qu Wenruo <wqu@suse.com>
> ---
> Please note in above case, the @type and @diff are not properly showed.
> That's another problem, will be addressed in later patches.
> ---
> tools/lib/traceevent/event-parse.c | 38 ++++++++++++++++++++++++++++++
> 1 file changed, 38 insertions(+)
>
> diff --git a/tools/lib/traceevent/event-parse.c b/tools/lib/traceevent/event-parse.c
> index d948475585ce..4f730ed527b0 100644
> --- a/tools/lib/traceevent/event-parse.c
> +++ b/tools/lib/traceevent/event-parse.c
> @@ -18,6 +18,7 @@
> #include <errno.h>
> #include <stdint.h>
> #include <limits.h>
> +#include <linux/uuid.h>
> #include <linux/time64.h>
>
> #include <netinet/in.h>
> @@ -4508,6 +4509,33 @@ get_bprint_format(void *data, int size __maybe_unused,
> return format;
> }
>
> +static void print_uuid_arg(struct trace_seq *s, void *data, int size,
> + struct tep_event *event, struct tep_print_arg *arg)
> +{
> + const char *fmt;
> + unsigned char *buf;
> +
> + fmt = "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x";
> + if (arg->type != TEP_PRINT_FIELD) {
> + trace_seq_printf(s, "ARG TYPE NOT FIELID but %d", arg->type);
> + return;
> + }
> +
> + if (!arg->field.field) {
> + arg->field.field = tep_find_any_field(event, arg->field.name);
> + if (!arg->field.field) {
> + do_warning("%s: field %s not found",
> + __func__, arg->field.name);
> + return;
> + }
> + }
> + buf = data + arg->field.field->offset;
> +
> + trace_seq_printf(s, fmt, buf[0], buf[1], buf[2], buf[3], buf[4], buf[5],
> + buf[6], buf[7], buf[8], buf[9], buf[10], buf[11], buf[12],
> + buf[13], buf[14], buf[15]);
> +}
> +
> static void print_mac_arg(struct trace_seq *s, int mac, void *data, int size,
> struct tep_event *event, struct tep_print_arg *arg)
> {
> @@ -5074,6 +5102,16 @@ static void pretty_print(struct trace_seq *s, void *data, int size, struct tep_e
> arg = arg->next;
> break;
> }
> + } else if (*ptr == 'U') {
> + /* Those finetunings are ignored for now */

I think this comment is cryptic. What do you mean by "finetunings"?

> + if (isalpha(ptr[1]))
> + ptr += 2;
> + else
> + ptr++;
> +
> + print_uuid_arg(s, data, size, event, arg);
> + arg = arg->next;
> + break;
> }
>
> /* fall through */
>

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