Re: [PATCH] fbdev: omapfb: avoid stack overflow warning

From: Helge Deller
Date: Wed Jan 04 2023 - 13:14:09 EST


On 12/15/22 18:02, Arnd Bergmann wrote:
From: Arnd Bergmann <arnd@xxxxxxxx>

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@xxxxxxxx>

applied to fbdev git tree.

Thanks!
Helge

---
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)