linux-kernel - [RFC 6/6] Revert "pstore/ram_core: Do not reset restored zone's position and size"

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Date:   Fri, 26 Oct 2018 11:00:42 -0700
From:   "Joel Fernandes (Google)" <joel@...lfernandes.org>
To:     linux-kernel@...r.kernel.org
Cc:     kernel-team@...roid.com,
        "Joel Fernandes (Google)" <joel@...lfernandes.org>,
        Anton Vorontsov <anton@...msg.org>,
        Colin Cross <ccross@...roid.com>,
        Kees Cook <keescook@...omium.org>,
        Tony Luck <tony.luck@...el.com>
Subject: [RFC 6/6] Revert "pstore/ram_core: Do not reset restored zone's position and size"

This reverts commit 25b63da64708212985c06c7f8b089d356efdd9cf.

Due to the commit which is being reverted here, it is not possible to
know if pstore's messages were from a previous boot, or from very old
boots. This creates an awkard situation where its unclear if crash or
other logs are from the previous boot or from very old boots. Also
typically we dump the pstore buffers after one reboot and are interested
in only the previous boot's crash so let us reset the buffer after we
save them.

Lastly, if we don't zap them, then I think it is possible that part of
the buffer will be from this boot and the other parts will be from
previous boots. So this revert fixes all of this by calling
persistent_ram_zap always.

Signed-off-by: Joel Fernandes (Google) <joel@...lfernandes.org>
---
 fs/pstore/ram_core.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/fs/pstore/ram_core.c b/fs/pstore/ram_core.c
index 1299aa3ea734..67d74dd97da1 100644
--- a/fs/pstore/ram_core.c
+++ b/fs/pstore/ram_core.c
@@ -504,7 +504,6 @@ static int persistent_ram_post_init(struct persistent_ram_zone *prz, u32 sig,
 			pr_debug("found existing buffer, size %zu, start %zu\n",
 				 buffer_size(prz), buffer_start(prz));
 			persistent_ram_save_old(prz);
-			return 0;
 		}
 	} else {
 		pr_debug("no valid data in buffer (sig = 0x%08x)\n",
-- 
2.19.1.568.g152ad8e336-goog