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* [tip:ras/core] RAS/CEC: Fix pfn insertion
@ 2019-06-08 21:25 tip-bot for Borislav Petkov
  0 siblings, 0 replies; only message in thread
From: tip-bot for Borislav Petkov @ 2019-06-08 21:25 UTC (permalink / raw)
  To: linux-tip-commits; +Cc: tony.luck, hpa, bp, tglx, mingo, linux-edac

Commit-ID:  6d8e294bf5f0e85c34e8b14b064e2965f53f38b0
Author:     Borislav Petkov <>
AuthorDate: Sat, 20 Apr 2019 12:53:05 +0200
Committer:  Borislav Petkov <>
CommitDate: Sat, 8 Jun 2019 17:32:00 +0200

RAS/CEC: Fix pfn insertion

When inserting random PFNs for debugging the CEC through
(debugfs)/ras/cec/pfn, depending on the return value of pfn_set(),
multiple values get inserted per a single write.

That is because simple_attr_write() interprets a retval of 0 as
success and claims the whole input. However, pfn_set() returns the
cec_add_elem() value, which, if > 0 and smaller than the whole input
length, makes glibc continue issuing the write syscall until there's
input left:


leading to those repeated calls.

Return 0 to fix that.

Signed-off-by: Borislav Petkov <>
Cc: Tony Luck <>
Cc: linux-edac <>
 drivers/ras/cec.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/ras/cec.c b/drivers/ras/cec.c
index 673f8a128397..f5795adc5a6e 100644
--- a/drivers/ras/cec.c
+++ b/drivers/ras/cec.c
@@ -369,7 +369,9 @@ static int pfn_set(void *data, u64 val)
 	*(u64 *)data = val;
-	return cec_add_elem(val);
+	cec_add_elem(val);
+	return 0;
 DEFINE_DEBUGFS_ATTRIBUTE(pfn_ops, u64_get, pfn_set, "0x%llx\n");

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2019-06-08 21:25 [tip:ras/core] RAS/CEC: Fix pfn insertion tip-bot for Borislav Petkov

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