Patch "powerpc/pseries: Duplicate dtl entries sometimes sent to userspace" has been added to the 3.12-stable tree

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This is a note to let you know that I've just added the patch titled

    powerpc/pseries: Duplicate dtl entries sometimes sent to userspace

to the 3.12-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     powerpc-pseries-duplicate-dtl-entries-sometimes-sent-to-userspace.patch
and it can be found in the queue-3.12 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.


>From 84b073868b9d9e754ae48b828337633d1b386482 Mon Sep 17 00:00:00 2001
From: Anton Blanchard <anton@xxxxxxxxx>
Date: Sun, 17 Nov 2013 11:39:05 +1100
Subject: powerpc/pseries: Duplicate dtl entries sometimes sent to userspace

From: Anton Blanchard <anton@xxxxxxxxx>

commit 84b073868b9d9e754ae48b828337633d1b386482 upstream.

When reading from the dispatch trace log (dtl) userspace interface, I
sometimes see duplicate entries. One example:

# hexdump -C dtl.out

00000000  07 04 00 0c 00 00 48 44  00 00 00 00 00 00 00 00
00000010  00 0c a0 b4 16 83 6d 68  00 00 00 00 00 00 00 00
00000020  00 00 00 00 10 00 13 50  80 00 00 00 00 00 d0 32

00000030  07 04 00 0c 00 00 48 44  00 00 00 00 00 00 00 00
00000040  00 0c a0 b4 16 83 6d 68  00 00 00 00 00 00 00 00
00000050  00 00 00 00 10 00 13 50  80 00 00 00 00 00 d0 32

The problem is in scan_dispatch_log() where we call dtl_consumer()
but bail out before incrementing the index.

To fix this I moved dtl_consumer() after the timebase comparison.

Signed-off-by: Anton Blanchard <anton@xxxxxxxxx>
Signed-off-by: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 arch/powerpc/kernel/time.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -213,8 +213,6 @@ static u64 scan_dispatch_log(u64 stop_tb
 	if (i == be64_to_cpu(vpa->dtl_idx))
 		return 0;
 	while (i < be64_to_cpu(vpa->dtl_idx)) {
-		if (dtl_consumer)
-			dtl_consumer(dtl, i);
 		dtb = be64_to_cpu(dtl->timebase);
 		tb_delta = be32_to_cpu(dtl->enqueue_to_dispatch_time) +
 			be32_to_cpu(dtl->ready_to_enqueue_time);
@@ -227,6 +225,8 @@ static u64 scan_dispatch_log(u64 stop_tb
 		}
 		if (dtb > stop_tb)
 			break;
+		if (dtl_consumer)
+			dtl_consumer(dtl, i);
 		stolen += tb_delta;
 		++i;
 		++dtl;


Patches currently in stable-queue which might be from anton@xxxxxxxxx are

queue-3.12/powerpc-ppc64-address-space-capped-at-32tb-mmap-randomisation-disabled.patch
queue-3.12/powerpc-pseries-duplicate-dtl-entries-sometimes-sent-to-userspace.patch
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