linux-kernel - [PATCH v2] firmware: dmi: handle missing DMI data gracefully

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Message-Id: <20171017181537.32540-1-ard.biesheuvel@linaro.org>
Date:   Tue, 17 Oct 2017 19:15:37 +0100
From:   Ard Biesheuvel <ard.biesheuvel@...aro.org>
To:     linux-kernel@...r.kernel.org, jdelvare@...e.com
Cc:     Ard Biesheuvel <ard.biesheuvel@...aro.org>
Subject: [PATCH v2] firmware: dmi: handle missing DMI data gracefully

Currently, when booting a kernel with DMI support on a platform that has
no DMI tables, the following output is emitted into the kernel log:

  [    0.128818] DMI not present or invalid.
  ...
  [    1.306659] dmi: Firmware registration failed.
  ...
  [    2.908681] dmi-sysfs: dmi entry is absent.

The first one is a pr_info(), but the subsequent ones are pr_err()s that
complain about a condition that is not really an error to begin with.

So let's clean this up, and give up silently if dma_available is not set.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>
---
v2: - don't use dmi_available in dmi-sysfs because it is not exported,
      instead, change pr_err to pr_debug

 drivers/firmware/dmi-sysfs.c | 2 +-
 drivers/firmware/dmi_scan.c  | 6 ++----
 2 files changed, 3 insertions(+), 5 deletions(-)

diff --git a/drivers/firmware/dmi-sysfs.c b/drivers/firmware/dmi-sysfs.c
index d5de6ee8466d..ecf2eeb5f6f9 100644
--- a/drivers/firmware/dmi-sysfs.c
+++ b/drivers/firmware/dmi-sysfs.c
@@ -652,7 +652,7 @@ static int __init dmi_sysfs_init(void)
 	int val;
 
 	if (!dmi_kobj) {
-		pr_err("dmi-sysfs: dmi entry is absent.\n");
+		pr_debug("dmi-sysfs: dmi entry is absent.\n");
 		error = -ENODATA;
 		goto err;
 	}
diff --git a/drivers/firmware/dmi_scan.c b/drivers/firmware/dmi_scan.c
index 783041964439..17a7425063c2 100644
--- a/drivers/firmware/dmi_scan.c
+++ b/drivers/firmware/dmi_scan.c
@@ -715,10 +715,8 @@ static int __init dmi_init(void)
 	u8 *dmi_table;
 	int ret = -ENOMEM;
 
-	if (!dmi_available) {
-		ret = -ENODATA;
-		goto err;
-	}
+	if (!dmi_available)
+		return 0;
 
 	/*
 	 * Set up dmi directory at /sys/firmware/dmi. This entry should stay
-- 
2.11.0