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From:   Arnd Bergmann <arnd@kernel.org>
To:     Helge Deller <deller@gmx.de>
Cc:     Arnd Bergmann <arnd@arndb.de>,
        Zhang Qilong <zhangqilong3@huawei.com>,
        linux-omap@vger.kernel.org, linux-fbdev@vger.kernel.org,
        dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org
Subject: [PATCH] fbdev: omapfb: avoid stack overflow warning
Date:   Thu, 15 Dec 2022 18:02:28 +0100
Message-Id: <20221215170234.2515030-1-arnd@kernel.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
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From: Arnd Bergmann <arnd@arndb.de>

The dsi_irq_stats structure is a little too big to fit on the
stack of a 32-bit task, depending on the specific gcc options:

fbdev/omap2/omapfb/dss/dsi.c: In function 'dsi_dump_dsidev_irqs':
fbdev/omap2/omapfb/dss/dsi.c:1621:1: error: the frame size of 1064 bytes is larger than 1024 bytes [-Werror=frame-larger-than=]

Since this is only a debugfs file, performance is not critical,
so just dynamically allocate it, and print an error message
in there in place of a failure code when the allocation fails.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/video/fbdev/omap2/omapfb/dss/dsi.c | 28 ++++++++++++++--------
 1 file changed, 18 insertions(+), 10 deletions(-)

diff --git a/drivers/video/fbdev/omap2/omapfb/dss/dsi.c b/drivers/video/fbdev/omap2/omapfb/dss/dsi.c
index 54b0f034c2ed..7cddb7b8ae34 100644
--- a/drivers/video/fbdev/omap2/omapfb/dss/dsi.c
+++ b/drivers/video/fbdev/omap2/omapfb/dss/dsi.c
@@ -1536,22 +1536,28 @@ static void dsi_dump_dsidev_irqs(struct platform_device *dsidev,
 {
 	struct dsi_data *dsi = dsi_get_dsidrv_data(dsidev);
 	unsigned long flags;
-	struct dsi_irq_stats stats;
+	struct dsi_irq_stats *stats;
+
+	stats = kzalloc(sizeof(*stats), GFP_KERNEL);
+	if (!stats) {
+		seq_printf(s, "out of memory\n");
+		return;
+	}
 
 	spin_lock_irqsave(&dsi->irq_stats_lock, flags);
 
-	stats = dsi->irq_stats;
+	*stats = dsi->irq_stats;
 	memset(&dsi->irq_stats, 0, sizeof(dsi->irq_stats));
 	dsi->irq_stats.last_reset = jiffies;
 
 	spin_unlock_irqrestore(&dsi->irq_stats_lock, flags);
 
 	seq_printf(s, "period %u ms\n",
-			jiffies_to_msecs(jiffies - stats.last_reset));
+			jiffies_to_msecs(jiffies - stats->last_reset));
 
-	seq_printf(s, "irqs %d\n", stats.irq_count);
+	seq_printf(s, "irqs %d\n", stats->irq_count);
 #define PIS(x) \
-	seq_printf(s, "%-20s %10d\n", #x, stats.dsi_irqs[ffs(DSI_IRQ_##x)-1])
+	seq_printf(s, "%-20s %10d\n", #x, stats->dsi_irqs[ffs(DSI_IRQ_##x)-1])
 
 	seq_printf(s, "-- DSI%d interrupts --\n", dsi->module_id + 1);
 	PIS(VC0);
@@ -1575,10 +1581,10 @@ static void dsi_dump_dsidev_irqs(struct platform_device *dsidev,
 
 #define PIS(x) \
 	seq_printf(s, "%-20s %10d %10d %10d %10d\n", #x, \
-			stats.vc_irqs[0][ffs(DSI_VC_IRQ_##x)-1], \
-			stats.vc_irqs[1][ffs(DSI_VC_IRQ_##x)-1], \
-			stats.vc_irqs[2][ffs(DSI_VC_IRQ_##x)-1], \
-			stats.vc_irqs[3][ffs(DSI_VC_IRQ_##x)-1]);
+			stats->vc_irqs[0][ffs(DSI_VC_IRQ_##x)-1], \
+			stats->vc_irqs[1][ffs(DSI_VC_IRQ_##x)-1], \
+			stats->vc_irqs[2][ffs(DSI_VC_IRQ_##x)-1], \
+			stats->vc_irqs[3][ffs(DSI_VC_IRQ_##x)-1]);
 
 	seq_printf(s, "-- VC interrupts --\n");
 	PIS(CS);
@@ -1594,7 +1600,7 @@ static void dsi_dump_dsidev_irqs(struct platform_device *dsidev,
 
 #define PIS(x) \
 	seq_printf(s, "%-20s %10d\n", #x, \
-			stats.cio_irqs[ffs(DSI_CIO_IRQ_##x)-1]);
+			stats->cio_irqs[ffs(DSI_CIO_IRQ_##x)-1]);
 
 	seq_printf(s, "-- CIO interrupts --\n");
 	PIS(ERRSYNCESC1);
@@ -1618,6 +1624,8 @@ static void dsi_dump_dsidev_irqs(struct platform_device *dsidev,
 	PIS(ULPSACTIVENOT_ALL0);
 	PIS(ULPSACTIVENOT_ALL1);
 #undef PIS
+
+	kfree(stats);
 }
 
 static void dsi1_dump_irqs(struct seq_file *s)
-- 
2.35.1