[QUEUED v20160212 07/19] intel_th: sth: Sanitize packet callback's return values

[Alexander Shishkin]

According to the stm class interface, the packet callback should return
an error if it is asked to generate packets that it doesn't support.
When it succeeds, it should return number of bytes consumed from its
payload. Currently, for FLAG packet it mistakenly returns 1.

This patch addresses these issues.

Signed-off-by: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
---
 drivers/hwtracing/intel_th/sth.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/hwtracing/intel_th/sth.c b/drivers/hwtracing/intel_th/sth.c
index 56101c33e1..e1aee61dd7 100644
--- a/drivers/hwtracing/intel_th/sth.c
+++ b/drivers/hwtracing/intel_th/sth.c
@@ -94,10 +94,13 @@ static ssize_t sth_stm_packet(struct stm_data *stm_data, unsigned int master,
 	case STP_PACKET_TRIG:
 		if (flags & STP_PACKET_TIMESTAMPED)
 			reg += 4;
-		iowrite8(*payload, sth->base + reg);
+		writeb_relaxed(*payload, sth->base + reg);
 		break;
 
 	case STP_PACKET_MERR:
+		if (size > 4)
+			size = 4;
+
 		sth_iowrite(&out->MERR, payload, size);
 		break;
 
@@ -107,8 +110,8 @@ static ssize_t sth_stm_packet(struct stm_data *stm_data, unsigned int master,
 		else
 			outp = (u64 __iomem *)&out->FLAG;
 
-		size = 1;
-		sth_iowrite(outp, payload, size);
+		size = 0;
+		writeb_relaxed(0, outp);
 		break;
 
 	case STP_PACKET_USER:
@@ -129,6 +132,8 @@ static ssize_t sth_stm_packet(struct stm_data *stm_data, unsigned int master,
 
 		sth_iowrite(outp, payload, size);
 		break;
+	default:
+		return -ENOTSUPP;
 	}
 
 	return size;
-- 
2.7.0