Commit-ID: fadd85f16a8ec3fee8af599e79a209682dc52348
Gitweb: http://git.kernel.org/tip/fadd85f16a8ec3fee8af599e79a209682dc52348
Author: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
AuthorDate: Mon, 23 Jan 2012 15:54:52 -0500
Committer: Tony Luck <tony.luck@xxxxxxxxx>
CommitDate: Wed, 22 Feb 2012 13:14:16 -0800
x86/mce: Fix return value of mce_chrdev_read() when erst is disabled
Current kernel MCE code reads ERST at the first reading of /dev/mcelog
(maybe in starting mcelogd,) even if the system does not support ERST,
which results in a fake "no such device" message (as described in [1].)
This problem is not critical, but can confuse system admins.
This patch fixes it by filtering the return value from lower (ACPI) layer.
[1] http://thread.gmane.org/gmane.linux.kernel/1060250
Reported by: Jon Masters <jonathan@xxxxxxxxxxxxxx>
Signed-off-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Cc: Andi Kleen <andi@xxxxxxxxxxxxxx>
Cc: Huang Ying <ying.huang@xxxxxxxxx>
Link: https://lkml.org/lkml/2012/1/23/299
Signed-off-by: Tony Luck <tony.luck@xxxxxxxxx>
---
arch/x86/kernel/cpu/mcheck/mce.c | 6 ++++++
1 files changed, 6 insertions(+), 0 deletions(-)
diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
index 4979a5d..87c56ba 100644
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -1541,6 +1541,12 @@ static int __mce_read_apei(char __user **ubuf, size_t usize)
/* Error or no more MCE record */
if (rc <= 0) {
mce_apei_read_done = 1;
+ /*
+ * When ERST is disabled, mce_chrdev_read() should return
+ * "no record" instead of "no device."
+ */
+ if (rc == -ENODEV)
+ return 0;
return rc;
}
rc = -EFAULT;
--
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