Re: [PATCH] Make efi-pstore return a unique id

From: Richard Weinberger
Date: Fri Nov 01 2013 - 12:29:27 EST


On Fri, Nov 1, 2013 at 5:14 PM, Madper Xie <cxie@xxxxxxxxxx> wrote:
>
> Pstore fs expects that backends provide a uniqued id which could avoid
> pstore making entries as duplication or denominating entries the same
> name. So I combine the timestamp, part and count into id.
>
> Signed-off-by: Madper Xie <cxie@xxxxxxxxxx>
> ---
> drivers/firmware/efi/efi-pstore.c | 22 ++++++++++++++++++----
> 1 file changed, 18 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/firmware/efi/efi-pstore.c b/drivers/firmware/efi/efi-pstore.c
> index 5002d50..0de9179 100644
> --- a/drivers/firmware/efi/efi-pstore.c
> +++ b/drivers/firmware/efi/efi-pstore.c
> @@ -39,6 +39,17 @@ struct pstore_read_data {
> char **buf;
> };
>
> +static u64 efi_generate_id(unsigned long timestamp, unsigned int part, int count)
> +{
> + char id_str[64];
> + u64 id = 0;
> +
> + sprintf(id_str, "%lu%u%d", timestamp, part, count);
> + if (kstrtoull(id_str, 10, &id))
> + pr_warn("efi-pstore: failed to generate id\n");
> + return id;
> +}

This is just odd. You make a string from three ints and then a parse
it to a int again.

> static int efi_pstore_read_func(struct efivar_entry *entry, void *data)
> {
> efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
> @@ -57,17 +68,18 @@ static int efi_pstore_read_func(struct efivar_entry *entry, void *data)
>
> if (sscanf(name, "dump-type%u-%u-%d-%lu-%c",
> cb_data->type, &part, &cnt, &time, &data_type) == 5) {
> - *cb_data->id = part;
> + *cb_data->id = efi_generate_id(time, part, cnt);
> *cb_data->count = cnt;
> cb_data->timespec->tv_sec = time;
> cb_data->timespec->tv_nsec = 0;
> +
> if (data_type == 'C')
> *cb_data->compressed = true;
> else
> *cb_data->compressed = false;
> } else if (sscanf(name, "dump-type%u-%u-%d-%lu",
> cb_data->type, &part, &cnt, &time) == 4) {
> - *cb_data->id = part;
> + *cb_data->id = efi_generate_id(time, part, cnt);
> *cb_data->count = cnt;
> cb_data->timespec->tv_sec = time;
> cb_data->timespec->tv_nsec = 0;
> @@ -79,7 +91,7 @@ static int efi_pstore_read_func(struct efivar_entry *entry, void *data)
> * which doesn't support holding
> * multiple logs, remains.
> */
> - *cb_data->id = part;
> + *cb_data->id = efi_generate_id(time, part, 0);
> *cb_data->count = 0;
> cb_data->timespec->tv_sec = time;
> cb_data->timespec->tv_nsec = 0;
> @@ -125,9 +137,11 @@ static int efi_pstore_write(enum pstore_type_id type,
> efi_char16_t efi_name[DUMP_NAME_LEN];
> efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
> int i, ret = 0;
> + unsigned long timestamp;
>
> + timestamp = get_seconds();
> sprintf(name, "dump-type%u-%u-%d-%lu-%c", type, part, count,
> - get_seconds(), compressed ? 'C' : 'D');
> + timestamp, compressed ? 'C' : 'D');
>
> for (i = 0; i < DUMP_NAME_LEN; i++)
> efi_name[i] = name[i];
> --
> 1.8.4.2
>
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--
Thanks,
//richard
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