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Message-ID: <CAGTjWtAb3XrsTtkvW=G0YN1RCVxYxcPksSh3jEogeEu4qWqv1Q@mail.gmail.com>
Date: Wed, 13 Jun 2012 13:24:54 -0700
From: Mike Waychison <mikew@...gle.com>
To: Seiji Aguchi <seiji.aguchi@....com>
Cc: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
"Matthew Garrett (mjg@...hat.com)" <mjg@...hat.com>,
"Luck, Tony (tony.luck@...el.com)" <tony.luck@...el.com>,
"gong.chen@...ux.intel.com" <gong.chen@...ux.intel.com>,
"keescook@...omium.org" <keescook@...omium.org>,
"rob@...dley.net" <rob@...dley.net>,
"dle-develop@...ts.sourceforge.net"
<dle-develop@...ts.sourceforge.net>,
Satoru Moriya <satoru.moriya@....com>
Subject: Re: [RFC][Patch]efi_pstore:Introduce an efi_pstore_overwrite
parameter to avoid missing messages in NVRAM
On Wed, Jun 13, 2012 at 6:42 AM, Seiji Aguchi <seiji.aguchi@....com> wrote:
>
> 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 shutdowns and boots up.
> 4. kernel panics again before a user checks the 1st panic messages in NVRAM.
>
>
> To avoid missing 1st panic messages, this patch adds a new parameter ,efi_pstore_overwrite,
> to efi_pstore so that we can specify whether efi_pstore overwrites existing entries in NVRAM or not.
>
>
> Signed-off-by: Seiji Aguchi <seiji.aguchi@....com>
Acked-by: Mike Waychison <mikew@...gle.com>
>
> ---
> Documentation/kernel-parameters.txt | 6 ++++
> drivers/firmware/efivars.c | 55 +++++++++++++++++++---------------
> 2 files changed, 37 insertions(+), 24 deletions(-)
>
> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
> index a92c5eb..990befa 100644
> --- a/Documentation/kernel-parameters.txt
> +++ b/Documentation/kernel-parameters.txt
> @@ -786,6 +786,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
> edd= [EDD]
> Format: {"off" | "on" | "skip[mbr]"}
>
> + efivars.efi_pstore_overwrite=
> + Specify whether efi_pstore overwrites existing entries
> + in NVRAM
> + Format: <bool> (1/Y/y=yes, 0/N/n=no)
> + default: yes
> +
> eisa_irq_edge= [PARISC,HW]
> See header of drivers/parisc/eisa.c.
>
> diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c index 47408e8..94fbd1d 100644
> --- a/drivers/firmware/efivars.c
> +++ b/drivers/firmware/efivars.c
> @@ -685,6 +685,10 @@ static ssize_t efi_pstore_read(u64 *id, enum pstore_type_id *type,
> return 0;
> }
>
> +static bool efi_pstore_overwrite = 1;
> +module_param_named(efi_pstore_overwrite, efi_pstore_overwrite,
> + bool, S_IRUGO | S_IWUSR);
> +
> static int efi_pstore_write(enum pstore_type_id type,
> enum kmsg_dump_reason reason, u64 *id,
> unsigned int part, size_t size, struct pstore_info *psi) @@ -705,33 +709,36 @@ static int efi_pstore_write(enum pstore_type_id type,
> for (i = 0; i < DUMP_NAME_LEN; i++)
> efi_name[i] = stub_name[i];
>
> - /*
> - * Clean up any entries with the same name
> - */
> + if (efi_pstore_overwrite) {
> + /*
> + * 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);
> + }
>
> - 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);
> }
>
> - if (found)
> - list_del(&found->list);
> -
> for (i = 0; i < DUMP_NAME_LEN; i++)
> efi_name[i] = name[i];
>
> --
> 1.7.1
--
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