[RFC 11/12] powerpc/powernv: Rework OPAL console write to remove conditional locking

[Ritesh Harjani (IBM)]

Clang's context analysis reports:
  opal.c:454:7: error: spinlock 'opal_write_lock' is not held on every path through here [-Werror,-Wthread-safety-analysis]
  opal.c:493:3: error: releasing spinlock 'opal_write_lock' that was not held [-Werror,-Wthread-safety-analysis]

This patch rework the OPAL console write function to remove this
conditional locking to fix the reported build errors while enabling
Clang context analysis. We could have marked __context_unsafe(),
but this anyways simplifies the locking a bit.

Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@xxxxxxxxx>
---
 arch/powerpc/platforms/powernv/opal.c | 30 ++++++++++++++++++---------
 1 file changed, 20 insertions(+), 10 deletions(-)

diff --git a/arch/powerpc/platforms/powernv/opal.c b/arch/powerpc/platforms/powernv/opal.c
index 1946dbdc9fa1..aea83c4be76d 100644
--- a/arch/powerpc/platforms/powernv/opal.c
+++ b/arch/powerpc/platforms/powernv/opal.c
@@ -438,19 +438,13 @@ ssize_t opal_get_chars(uint32_t vtermno, u8 *buf, size_t count)
 	return 0;
 }
 
-static ssize_t __opal_put_chars(uint32_t vtermno, const u8 *data,
-				size_t total_len, bool atomic)
+static ssize_t __opal_put_chars_unlocked(uint32_t vtermno, const u8 *data,
+					 size_t total_len, bool atomic)
 {
-	unsigned long flags = 0 /* shut up gcc */;
 	ssize_t written;
 	__be64 olen;
 	s64 rc;
 
-	if (!opal.entry)
-		return -ENODEV;
-
-	if (atomic)
-		spin_lock_irqsave(&opal_write_lock, flags);
 	rc = opal_console_write_buffer_space(vtermno, &olen);
 	if (rc || be64_to_cpu(olen) < total_len) {
 		/* Closed -> drop characters */
@@ -489,10 +483,26 @@ static ssize_t __opal_put_chars(uint32_t vtermno, const u8 *data,
 	}
 
 out:
-	if (atomic)
+	return written;
+}
+
+static ssize_t __opal_put_chars(uint32_t vtermno, const u8 *data,
+				size_t total_len, bool atomic)
+{
+	unsigned long flags = 0;
+	ssize_t written;
+
+	if (!opal.entry)
+		return -ENODEV;
+
+	if (atomic) {
+		spin_lock_irqsave(&opal_write_lock, flags);
+		written = __opal_put_chars_unlocked(vtermno, data, total_len, true);
 		spin_unlock_irqrestore(&opal_write_lock, flags);
+		return written;
+	}
 
-	return written;
+	return __opal_put_chars_unlocked(vtermno, data, total_len, false);
 }
 
 ssize_t opal_put_chars(uint32_t vtermno, const u8 *data, size_t total_len)
-- 
2.39.5