linux-kernel - [PATCH v4 3/7] efi_pstore: Remove a logic erasing entries from a write callback to hold multiple logs

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Message-ID: <A5ED84D3BB3A384992CBB9C77DEDA4D4138B1E27@USINDEM103.corp.hds.com>
Date:	Tue, 30 Oct 2012 20:01:38 +0000
From:	Seiji Aguchi <seiji.aguchi@....com>
To:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	"Luck, Tony (tony.luck@...el.com)" <tony.luck@...el.com>,
	"Matthew Garrett (mjg@...hat.com)" <mjg@...hat.com>,
	"dzickus@...hat.com" <dzickus@...hat.com>
CC:	"dle-develop@...ts.sourceforge.net" 
	<dle-develop@...ts.sourceforge.net>,
	Satoru Moriya <satoru.moriya@....com>
Subject: [PATCH v4 3/7] efi_pstore: Remove a logic erasing entries from a
 write callback to hold multiple logs


[Issue]

Currently, efi_pstore driver simply overwrites existing panic messages in NVRAM.
So, in the following scenario, we will lose 1st panic messages.

1. kernel panics.
2. efi_pstore is kicked and writes panic messages to NVRAM.
3. system reboots.
4. kernel panics again before a user checks the 1st panic messages in NVRAM.

[Solution]

A reasonable solution to fix the issue is just holding multiple logs without erasing
existing entries.
This patch removes a logic erasing existing entries in a write callback
because the logic is not needed in the write callback to support holding multiple logs.

Signed-off-by: Seiji Aguchi <seiji.aguchi@....com>
---
 drivers/firmware/efivars.c |   39 ++-------------------------------------
 1 files changed, 2 insertions(+), 37 deletions(-)

diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
index bee14cc..fbe9202 100644
--- a/drivers/firmware/efivars.c
+++ b/drivers/firmware/efivars.c
@@ -701,18 +701,13 @@ static int efi_pstore_write(enum pstore_type_id type,
 		unsigned int part, size_t size, struct pstore_info *psi)
 {
 	char name[DUMP_NAME_LEN];
-	char stub_name[DUMP_NAME_LEN];
 	efi_char16_t efi_name[DUMP_NAME_LEN];
 	efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
 	struct efivars *efivars = psi->data;
-	struct efivar_entry *entry, *found = NULL;
 	int i, ret = 0;
 	u64 storage_space, remaining_space, max_variable_size;
 	efi_status_t status = EFI_NOT_FOUND;
 
-	sprintf(stub_name, "dump-type%u-%u-", type, part);
-	sprintf(name, "%s%lu", stub_name, get_seconds());
-
 	spin_lock(&efivars->lock);
 
 	/*
@@ -730,35 +725,8 @@ static int efi_pstore_write(enum pstore_type_id type,
 		return -ENOSPC;
 	}
 
-	for (i = 0; i < DUMP_NAME_LEN; i++)
-		efi_name[i] = stub_name[i];
-
-	/*
-	 * Clean up any entries with the same name
-	 */
-
-	list_for_each_entry(entry, &efivars->list, list) {
-		get_var_data_locked(efivars, &entry->var);
-
-		if (efi_guidcmp(entry->var.VendorGuid, vendor))
-			continue;
-		if (utf16_strncmp(entry->var.VariableName, efi_name,
-				  utf16_strlen(efi_name)))
-			continue;
-		/* Needs to be a prefix */
-		if (entry->var.VariableName[utf16_strlen(efi_name)] == 0)
-			continue;
-
-		/* found */
-		found = entry;
-		efivars->ops->set_variable(entry->var.VariableName,
-					   &entry->var.VendorGuid,
-					   PSTORE_EFI_ATTRIBUTES,
-					   0, NULL);
-	}
-
-	if (found)
-		list_del(&found->list);
+	sprintf(name, "dump-type%u-%u-%lu", type, part,
+		get_seconds());
 
 	for (i = 0; i < DUMP_NAME_LEN; i++)
 		efi_name[i] = name[i];
@@ -768,9 +736,6 @@ static int efi_pstore_write(enum pstore_type_id type,
 
 	spin_unlock(&efivars->lock);
 
-	if (found)
-		efivar_unregister(found);
-
 	if (size)
 		ret = efivar_create_sysfs_entry(efivars,
 					  utf16_strsize(efi_name,
-- 
1.7.1
--
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