linux-kernel - RE: [PATCH 0/2] make all stored entries accessible.

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Date:	Wed, 30 Oct 2013 21:11:51 +0000
From:	"Luck, Tony" <tony.luck@...el.com>
To:	Madper Xie <cxie@...hat.com>,
	"keescook@...omium.org" <keescook@...omium.org>,
	"ccross@...roid.com" <ccross@...roid.com>,
	"anton@...msg.org" <anton@...msg.org>,
	"seiji.aguchi@....com" <seiji.aguchi@....com>
CC:	"linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"bbboson@...il.com" <bbboson@...il.com>
Subject: RE: [PATCH 0/2] make all stored entries accessible.

> 1. checking type, id, psi, count and timespec when finding duplicate entries.
> 2. adding count and timestamp  for differentiating.

Ah - I was expecting that the backend driver would have a unique "id" for
each record stored ... but is seems that this isn't true for efivars.

I just tried this patch series out with the erst backend. It seems to work, but
I was confused for a while by the filenames that I see in the pstore filesystem. There is a "--"
in the name that I couldn't quite figure out:

-r--r--r-- 1 root root 17498 Oct 30 13:41 dmesg-erst-5940651313304961025--2129078373-1383165669
-r--r--r-- 1 root root 17511 Oct 30 13:41 dmesg-erst-5940651313304961026--2129078373-1383165669
-r--r--r-- 1 root root 17530 Oct 30 13:41 dmesg-erst-5940651313304961027--2129078373-1383165669
-r--r--r-- 1 root root 17492 Oct 30 13:41 dmesg-erst-5940651313304961028--2129078373-1383165669
-r--r--r-- 1 root root 17499 Oct 30 13:41 dmesg-erst-5940651313304961029--2129078373-1383165669
-r--r--r-- 1 root root 17512 Oct 30 13:41 dmesg-erst-5940651313304961030--2129078373-1383165669
-r--r--r-- 1 root root 17531 Oct 30 13:41 dmesg-erst-5940651313304961031--2129078373-1383165669
-r--r--r-- 1 root root 17488 Oct 30 13:44 dmesg-erst-5940652283967569921--2129078373-1383165895
-r--r--r-- 1 root root 17512 Oct 30 13:44 dmesg-erst-5940652283967569922--2129078373-1383165895
-r--r--r-- 1 root root 17512 Oct 30 13:44 dmesg-erst-5940652283967569923--2129078373-1383165895
-r--r--r-- 1 root root 17500 Oct 30 13:44 dmesg-erst-5940652283967569924--2129078373-1383165895
-r--r--r-- 1 root root 17536 Oct 30 13:44 dmesg-erst-5940652283967569925--2129078373-1383165895
-r--r--r-- 1 root root 17513 Oct 30 13:44 dmesg-erst-5940652283967569926--2129078373-1383165895
-r--r--r-- 1 root root 17513 Oct 30 13:44 dmesg-erst-5940652283967569927--2129078373-1383165895
-r--r--r-- 1 root root 17501 Oct 30 13:44 dmesg-erst-5940652283967569928--2129078373-1383165895

The filename came from:
+               sprintf(name, "dmesg-%s-%lld-%d-%ld%s", psname, id, count,
+                       timestamp, compressed ? ".enc.z" : "");

So I guess that "count" is  -2129078373 - which is some uninitialized junk from the stack frame
of pstore_get_records() for the "int count" variable ... the erst reader function doesn't touch it.

I'll add an initializer "int count = 0;" there when applying the patches.

-Tony
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