[PATCH v2] usb: dwc3: debugfs: Prevent any register access when devices is runtime suspended

* [PATCH v2] usb: dwc3: debugfs: Prevent any register access when devices is runtime suspended
@ 2023-03-15 12:47 Udipto Goswami
  2023-03-15 17:55 ` Jack Pham
  0 siblings, 1 reply; 3+ messages in thread
From: Udipto Goswami @ 2023-03-15 12:47 UTC (permalink / raw)
  To: Thinh Nguyen, Greg Kroah-Hartman
  Cc: Pratham Pratap, Jack Pham, linux-usb, Udipto Goswami

When the dwc3 device is runtime suspended, various required clocks would
get disabled and it is not guaranteed that access to any registers would
work. Depending on the SoC glue, a register read could be as benign as
returning 0 or be fatal enough to hang the system.

In order to prevent such scenarios of fatal errors, bail out of debugfs
function is dwc3 is suspended.

Signed-off-by: Udipto Goswami <quic_ugoswami@quicinc.com>
---
v2: Replaced return 0 with -EINVAL & seq_puts with pr_err.

 drivers/usb/dwc3/debugfs.c | 50 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 50 insertions(+)

diff --git a/drivers/usb/dwc3/debugfs.c b/drivers/usb/dwc3/debugfs.c
index 850df0e6bcab..0e6cf7b89f8b 100644
--- a/drivers/usb/dwc3/debugfs.c
+++ b/drivers/usb/dwc3/debugfs.c
@@ -544,6 +544,11 @@ static int dwc3_link_state_show(struct seq_file *s, void *unused)
 	u32			reg;
 	u8			speed;
 
+	if (pm_runtime_suspended(dwc->dev)) {
+		pr_err("Invalid operation, DWC3 suspended!");
+		return -EINVAL;
+	}
+
 	spin_lock_irqsave(&dwc->lock, flags);
 	reg = dwc3_readl(dwc->regs, DWC3_GSTS);
 	if (DWC3_GSTS_CURMOD(reg) != DWC3_GSTS_CURMOD_DEVICE) {
@@ -580,6 +585,11 @@ static ssize_t dwc3_link_state_write(struct file *file,
 	u32			reg;
 	u8			speed;
 
+	if (pm_runtime_suspended(dwc->dev)) {
+		pr_err("Invalid operation, DWC3 suspended!");
+		return -EINVAL;
+	}
+
 	if (copy_from_user(&buf, ubuf, min_t(size_t, sizeof(buf) - 1, count)))
 		return -EFAULT;
 
@@ -641,6 +651,11 @@ static int dwc3_tx_fifo_size_show(struct seq_file *s, void *unused)
 	u32			mdwidth;
 	u32			val;
 
+	if (pm_runtime_suspended(dwc->dev)) {
+		pr_err("Invalid operation, DWC3 suspended!");
+		return -EINVAL;
+	}
+
 	spin_lock_irqsave(&dwc->lock, flags);
 	val = dwc3_core_fifo_space(dep, DWC3_TXFIFO);
 
@@ -663,6 +678,11 @@ static int dwc3_rx_fifo_size_show(struct seq_file *s, void *unused)
 	u32			mdwidth;
 	u32			val;
 
+	if (pm_runtime_suspended(dwc->dev)) {
+		pr_err("Invalid operation, DWC3 suspended!");
+		return -EINVAL;
+	}
+
 	spin_lock_irqsave(&dwc->lock, flags);
 	val = dwc3_core_fifo_space(dep, DWC3_RXFIFO);
 
@@ -684,6 +704,11 @@ static int dwc3_tx_request_queue_show(struct seq_file *s, void *unused)
 	unsigned long		flags;
 	u32			val;
 
+	if (pm_runtime_suspended(dwc->dev)) {
+		pr_err("Invalid operation, DWC3 suspended!");
+		return -EINVAL;
+	}
+
 	spin_lock_irqsave(&dwc->lock, flags);
 	val = dwc3_core_fifo_space(dep, DWC3_TXREQQ);
 	seq_printf(s, "%u\n", val);
@@ -699,6 +724,11 @@ static int dwc3_rx_request_queue_show(struct seq_file *s, void *unused)
 	unsigned long		flags;
 	u32			val;
 
+	if (pm_runtime_suspended(dwc->dev)) {
+		pr_err("Invalid operation, DWC3 suspended!");
+		return -EINVAL;
+	}
+
 	spin_lock_irqsave(&dwc->lock, flags);
 	val = dwc3_core_fifo_space(dep, DWC3_RXREQQ);
 	seq_printf(s, "%u\n", val);
@@ -714,6 +744,11 @@ static int dwc3_rx_info_queue_show(struct seq_file *s, void *unused)
 	unsigned long		flags;
 	u32			val;
 
+	if (pm_runtime_suspended(dwc->dev)) {
+		pr_err("Invalid operation, DWC3 suspended!");
+		return -EINVAL;
+	}
+
 	spin_lock_irqsave(&dwc->lock, flags);
 	val = dwc3_core_fifo_space(dep, DWC3_RXINFOQ);
 	seq_printf(s, "%u\n", val);
@@ -729,6 +764,11 @@ static int dwc3_descriptor_fetch_queue_show(struct seq_file *s, void *unused)
 	unsigned long		flags;
 	u32			val;
 
+	if (pm_runtime_suspended(dwc->dev)) {
+		pr_err("Invalid operation, DWC3 suspended!");
+		return -EINVAL;
+	}
+
 	spin_lock_irqsave(&dwc->lock, flags);
 	val = dwc3_core_fifo_space(dep, DWC3_DESCFETCHQ);
 	seq_printf(s, "%u\n", val);
@@ -744,6 +784,11 @@ static int dwc3_event_queue_show(struct seq_file *s, void *unused)
 	unsigned long		flags;
 	u32			val;
 
+	if (pm_runtime_suspended(dwc->dev)) {
+		pr_err("Invalid operation, DWC3 suspended!");
+		return -EINVAL;
+	}
+
 	spin_lock_irqsave(&dwc->lock, flags);
 	val = dwc3_core_fifo_space(dep, DWC3_EVENTQ);
 	seq_printf(s, "%u\n", val);
@@ -835,6 +880,11 @@ static int dwc3_ep_info_register_show(struct seq_file *s, void *unused)
 	u32			upper_32_bits;
 	u32			reg;
 
+	if (pm_runtime_suspended(dwc->dev)) {
+		pr_err("Invalid operation, DWC3 suspended!");
+		return -EINVAL;
+	}
+
 	spin_lock_irqsave(&dwc->lock, flags);
 	reg = DWC3_GDBGLSPMUX_EPSELECT(dep->number);
 	dwc3_writel(dwc->regs, DWC3_GDBGLSPMUX, reg);
-- 
2.17.1


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