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Commit dd230fec authored by Seiji Aguchi's avatar Seiji Aguchi Committed by Tony Luck
Browse files

efi_pstore: Add a logic erasing entries to an erase callback 



[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 freshly adds a logic erasing existing entries, which shared with a write callback,
to an erase callback.
To support holding multiple logs, the write callback doesn't need to erase any entries and
it will be removed in a subsequent patch.

Signed-off-by: default avatarSeiji Aguchi <seiji.aguchi@hds.com>
Acked-by: default avatarMike Waychison <mikew@google.com>
Signed-off-by: default avatarTony Luck <tony.luck@intel.com>
parent d80a361d

drivers/firmware/efivars.c

+45 −1
Original line number Diff line number Diff line
@@ -784,7 +784,51 @@ static int efi_pstore_write(enum pstore_type_id type, 
static int efi_pstore_erase(enum pstore_type_id type, u64 id,

			    struct pstore_info *psi)

{

	efi_pstore_write(type, 0, &id, (unsigned int)id, 0, psi);

	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;



	sprintf(stub_name, "dump-type%u-%u-", type, (unsigned int)id);



	spin_lock(&efivars->lock);



	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);



	spin_unlock(&efivars->lock);



	if (found)

		efivar_unregister(found);



	return 0;

}