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

2013-11-20 Thread Madper Xie
rich...@nod.at writes: > Am 01.11.2013 20:22, schrieb Seiji Aguchi: >>> >>> Agreed. I liked your ((timestamp * 100 + part) * 100 + count function much >>> more than this. >> >> I was worried that the part and count could be more than 100. >> If it happens, the id may not be unique... >> >> But

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

2013-11-02 Thread Seiji Aguchi
> How does efivars backend handle "unlink(2)" in the pstore file system. > pstore will call the backend->erase function passing the "id". The > backend should then erase the right record from persistent storage. > > With the ((timestamp * 100 + part) * 100 + count function - you can > easily rev

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

2013-11-01 Thread Madper Xie
rich...@nod.at writes: > Am 01.11.2013 20:22, schrieb Seiji Aguchi: > +{ > + 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:

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

2013-11-01 Thread Tony Luck
On Fri, Nov 1, 2013 at 1:57 PM, Seiji Aguchi wrote: >> What about feeding the bytes of all three integers into a non-cryptographic >> hash function? >> Using this way you get a cheap unique id. > > It is reasonable to me. How does efivars backend handle "unlink(2)" in the pstore file system. pst

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

2013-11-01 Thread Seiji Aguchi
> What about feeding the bytes of all three integers into a non-cryptographic > hash function? > Using this way you get a cheap unique id. It is reasonable to me. Seiji

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

2013-11-01 Thread Richard Weinberger
Am 01.11.2013 20:22, schrieb Seiji Aguchi: +{ + 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"); +

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

2013-11-01 Thread Seiji Aguchi
> >> +{ > >> + 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 ju

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

2013-11-01 Thread Tony Luck
>> +static u64 efi_generate_id(unsigned long timestamp, unsigned int part, int >> count) I don't think the "efi_" prefix is needed here. For one thing the function is static, so no name space pollution worries. For another - it makes it look like this is some thing defined in EFI standard. If "g

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

2013-11-01 Thread Richard Weinberger
On Fri, Nov 1, 2013 at 5:14 PM, Madper Xie 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 > --- > d

[PATCH] Make efi-pstore return a unique id

2013-11-01 Thread Madper Xie
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 --- drivers/firmware/efi/efi-pstore.c | 22 ++ 1 f