linux-kernel - [PATCH] efi: Avoid sysfs spew on reboot and panic

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Date:	Wed, 7 Mar 2012 17:49:59 -0500
From:	Seiji Aguchi <seiji.aguchi@....com>
To:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Luck, Tony (tony.luck@...el.com)" <tony.luck@...el.com>,
	"Chen Gong (gong.chen@...ux.intel.com)" <gong.chen@...ux.intel.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] efi: Avoid sysfs spew on reboot and panic

Hi,

This patch just modified Matthew's patch which has not included in upstream to fit current upstream code.

https://lkml.org/lkml/2011/9/20/468

 Right now all pstore accesses to efivars will delete or create new sysfs  nodes. This is less than ideal if we've panicked or rebooting for  following reasons.
  - efi_pstore may not work if kernel panics in interrupt context, since
    cpu can sleep while creating sysfs files.
  - we don't need to create sysfs if we've panicked or rebooting, because
    no one can access to it.


Signed-off-by: Seiji Aguchi <seiji.aguchi@....com>
Signed-off-by: Matthew Garrett <mjg@...hat.com>
---
 drivers/firmware/efivars.c |   10 ++++++++++
 1 files changed, 10 insertions(+), 0 deletions(-)

diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
index d25599f..34c8890 100644
--- a/drivers/firmware/efivars.c
+++ b/drivers/firmware/efivars.c
@@ -550,6 +550,16 @@ static int efi_pstore_write(enum pstore_type_id type,
 
 	spin_unlock(&efivars->lock);
 
+	/*
+	 * If it's more severe than KMSG_DUMP_OOPS then we're already dead.
+	 * Don't bother playing with sysfs.
+	 */
+
+	if (reason != KMSG_DUMP_OOPS) {
+		*id = part;
+		return ret;
+	}
+
 	if (found)
 		efivar_unregister(found);
 
-- 1.7.1
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