linux-kernel - [PATCH 4.14 278/293] drm/crc: Only report a single overflow when a CRC fd is opened

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Date:   Mon, 29 Jul 2019 21:22:49 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Ville Syrjälä 
        <ville.syrjala@...ux.intel.com>, Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.14 278/293] drm/crc: Only report a single overflow when a CRC fd is opened

[ Upstream commit a012024571d98e2e4bf29a9168fb7ddc44b7ab86 ]

This reduces the amount of spam when you debug a CRC reading
program.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>
[mlankhorst: Change bool overflow to was_overflow (Ville)]
Reviewed-by: Ville Syrjälä <ville.syrjala@...ux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180418125121.72081-1-maarten.lankhorst@linux.intel.com
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/drm_debugfs_crc.c | 9 ++++++++-
 include/drm/drm_debugfs_crc.h     | 3 ++-
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_debugfs_crc.c b/drivers/gpu/drm/drm_debugfs_crc.c
index 021813b20e97..f689c75474e5 100644
--- a/drivers/gpu/drm/drm_debugfs_crc.c
+++ b/drivers/gpu/drm/drm_debugfs_crc.c
@@ -139,6 +139,7 @@ static int crtc_crc_data_count(struct drm_crtc_crc *crc)
 static void crtc_crc_cleanup(struct drm_crtc_crc *crc)
 {
 	kfree(crc->entries);
+	crc->overflow = false;
 	crc->entries = NULL;
 	crc->head = 0;
 	crc->tail = 0;
@@ -373,8 +374,14 @@ int drm_crtc_add_crc_entry(struct drm_crtc *crtc, bool has_frame,
 	tail = crc->tail;
 
 	if (CIRC_SPACE(head, tail, DRM_CRC_ENTRIES_NR) < 1) {
+		bool was_overflow = crc->overflow;
+
+		crc->overflow = true;
 		spin_unlock(&crc->lock);
-		DRM_ERROR("Overflow of CRC buffer, userspace reads too slow.\n");
+
+		if (!was_overflow)
+			DRM_ERROR("Overflow of CRC buffer, userspace reads too slow.\n");
+
 		return -ENOBUFS;
 	}
 
diff --git a/include/drm/drm_debugfs_crc.h b/include/drm/drm_debugfs_crc.h
index 7d63b1d4adb9..b225eeb30d05 100644
--- a/include/drm/drm_debugfs_crc.h
+++ b/include/drm/drm_debugfs_crc.h
@@ -43,6 +43,7 @@ struct drm_crtc_crc_entry {
  * @lock: protects the fields in this struct
  * @source: name of the currently configured source of CRCs
  * @opened: whether userspace has opened the data file for reading
+ * @overflow: whether an overflow occured.
  * @entries: array of entries, with size of %DRM_CRC_ENTRIES_NR
  * @head: head of circular queue
  * @tail: tail of circular queue
@@ -52,7 +53,7 @@ struct drm_crtc_crc_entry {
 struct drm_crtc_crc {
 	spinlock_t lock;
 	const char *source;
-	bool opened;
+	bool opened, overflow;
 	struct drm_crtc_crc_entry *entries;
 	int head, tail;
 	size_t values_cnt;
-- 
2.20.1