linux-kernel - [PATCH] coresight: fix the link between orphan connection and newly added device

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Message-ID: <1421148196-17928-1-git-send-email-xiakaixu@huawei.com>
Date:	Tue, 13 Jan 2015 19:23:16 +0800
From:	Kaixu Xia <xiakaixu@...wei.com>
To:	<mathieu.poirier@...aro.org>
CC:	<gregkh@...uxfoundation.org>, <linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>, <xiakaixu@...wei.com>,
	<kaixu.xia@...aro.org>
Subject: [PATCH] coresight: fix the link between orphan connection and newly added device

When found a component that has one orphan connection, we should
validate if it match the newly added device. If it does not match,
this component still has an orphan connection(still_orphan = true).
The process should be like this. The original logic maybe cause
path building failed.

The tested result as follows. 
pre:
/sys/bus/coresight/devices # echo 1 > e3c42000.etb/enable_sink
/sys/bus/coresight/devices # echo 1 > e3c7c000.ptm/enable_source
[   15.527692] Unable to handle kernel NULL pointer dereference at virtual address 00000124
[   15.555142] pgd = c2294000
[   15.564226] [00000124] *pgd=3d393831, *pte=00000000, *ppte=00000000
[   15.585391] Internal error: Oops: 817 [#1] PREEMPT SMP ARM
[   15.603807] CPU: 0 PID: 144 Comm: sh Not tainted 3.17.0-rc1-12634-g1222fe0-dirty #3
[   15.629490] task: ed3803c0 ti: c213a000 task.ti: c213a000
[   15.647627] PC is at coresight_build_paths+0x1c/0x314
[   15.664579] LR is at coresight_build_paths+0x6c/0x314
[   15.681526] pc : [<c02da20c>]    lr : [<c02da25c>]    psr: 20000013
[   15.681526] sp : c213be88  ip : c02da800  fp : 00000000
[   15.720023] r10: 00000002  r9 : ed13250c  r8 : 00000001
[   15.737549] r7 : c213bee8  r6 : ffffffea  r5 : 00000000  r4 : 00000124
[   15.759446] r3 : ed216f24  r2 : 00000001  r1 : c213bee8  r0 : 00000000
[   15.781346] Flags: nzCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment user

post:
/sys/bus/coresight/devices # echo 1 > e3c42000.etb/enable_sink
/sys/bus/coresight/devices # echo 1 > e3c7c000.ptm/enable_source
[   59.934255] coresight-etb10 e3c42000.etb: ETB enabled
[   59.951317] coresight-replicator replicator0: REPLICATOR enabled
[   59.971581] coresight-funnel e3c41000.funnel: FUNNEL inport 0 enabled
[   59.993334] coresight-etm3x e3c7c000.ptm: ETM tracing enabled

Signed-off-by: Kaixu Xia <xiakaixu@...wei.com>
---
 drivers/coresight/coresight.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/coresight/coresight.c b/drivers/coresight/coresight.c
index 6e0181f..11968b7 100644
--- a/drivers/coresight/coresight.c
+++ b/drivers/coresight/coresight.c
@@ -504,11 +504,12 @@ static int coresight_orphan_match(struct device *dev, void *data)
 		/* We have found at least one orphan connection */
 		if (conn->child_dev == NULL) {
 			/* Does it match this newly added device? */
-			if (!strcmp(dev_name(&csdev->dev), conn->child_name))
+			if (!strcmp(dev_name(&csdev->dev), conn->child_name)) {
 				conn->child_dev = csdev;
-		} else {
-			/* Too bad, this component still has an orphan */
-			still_orphan = true;
+			} else {
+				/* Too bad, this component still has an orphan */
+				still_orphan = true;
+			}
 		}
 	}
 
-- 
1.8.5.5

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