From: Joseph Tilahun jtilahun@astranis.com
[ Upstream commit 33a2515abd45c64911955ff1da179589db54f99f ]
The serial info sometimes produces negative TX/RX counts. E.g.:
3: uart:FSL_LPUART mmio:0x02970000 irq:46 tx:-1595870545 rx:339619 RTS|CTS|DTR|DSR|CD
It appears that the print format specifiers don't match with the types of the respective variables. E.g.: All of the fields in struct uart_icount are u32, but the format specifier used is %d, even though u32 is unsigned and %d is for signed integers. Update drivers/tty/serial/serial_core.c to use the proper format specifiers. Reference https://docs.kernel.org/core-api/printk-formats.html as the documentation for what format specifiers are the proper ones to use for a given C type.
Signed-off-by: Joseph Tilahun jtilahun@astranis.com Link: https://lore.kernel.org/r/20250610065653.3750067-1-jtilahun@astranis.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin sashal@kernel.org ---
LLM Generated explanations, may be completely bogus:
**YES**
This commit should be backported to stable kernel trees for the following reasons:
1. **It fixes a real user-visible bug**: The commit fixes incorrect format specifiers that cause negative values to be displayed for TX/RX counts in `/proc/tty/driver/serial`. The example shows: ``` 3: uart:FSL_LPUART mmio:0x02970000 irq:46 tx:-1595870545 rx:339619 ``` This is clearly wrong as TX/RX counts should never be negative.
2. **The fix is simple and contained**: The changes only modify format specifiers from `%d` (signed) to `%u` (unsigned) in print statements. Looking at the code: - All `uart_icount` fields (tx, rx, frame, parity, brk, overrun, buf_overrun) are defined as `__u32` (unsigned 32-bit) - `port->line` is `unsigned int` - `port->irq` is `unsigned int` - `port->uartclk` is `unsigned int` - Other fields like `close_delay`, `closing_wait`, `io_type`, `iomem_reg_shift` are also unsigned types
3. **Low risk of regression**: The changes are purely cosmetic - they only affect how values are displayed, not the actual functionality. No logic changes, no structural changes, just format string corrections.
4. **Affects a core subsystem**: The serial core is used by many serial drivers, so this bug affects multiple platforms and drivers. The fix benefits all users of the serial subsystem.
5. **Follows stable tree rules**: This is exactly the type of fix suitable for stable: - Fixes an actual bug (incorrect display of statistics) - Minimal change - Obviously correct (matching format specifiers to variable types) - No new features or architectural changes
The commit is a straightforward correctness fix that improves the reliability of kernel diagnostics output without any risk of breaking functionality.
drivers/tty/serial/serial_core.c | 44 ++++++++++++++++---------------- 1 file changed, 22 insertions(+), 22 deletions(-)
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index d94d73e45fb6..440303566b14 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -1353,28 +1353,28 @@ static void uart_sanitize_serial_rs485_delays(struct uart_port *port, if (!port->rs485_supported.delay_rts_before_send) { if (rs485->delay_rts_before_send) { dev_warn_ratelimited(port->dev, - "%s (%d): RTS delay before sending not supported\n", + "%s (%u): RTS delay before sending not supported\n", port->name, port->line); } rs485->delay_rts_before_send = 0; } else if (rs485->delay_rts_before_send > RS485_MAX_RTS_DELAY) { rs485->delay_rts_before_send = RS485_MAX_RTS_DELAY; dev_warn_ratelimited(port->dev, - "%s (%d): RTS delay before sending clamped to %u ms\n", + "%s (%u): RTS delay before sending clamped to %u ms\n", port->name, port->line, rs485->delay_rts_before_send); }
if (!port->rs485_supported.delay_rts_after_send) { if (rs485->delay_rts_after_send) { dev_warn_ratelimited(port->dev, - "%s (%d): RTS delay after sending not supported\n", + "%s (%u): RTS delay after sending not supported\n", port->name, port->line); } rs485->delay_rts_after_send = 0; } else if (rs485->delay_rts_after_send > RS485_MAX_RTS_DELAY) { rs485->delay_rts_after_send = RS485_MAX_RTS_DELAY; dev_warn_ratelimited(port->dev, - "%s (%d): RTS delay after sending clamped to %u ms\n", + "%s (%u): RTS delay after sending clamped to %u ms\n", port->name, port->line, rs485->delay_rts_after_send); } } @@ -1404,14 +1404,14 @@ static void uart_sanitize_serial_rs485(struct uart_port *port, struct serial_rs4 rs485->flags &= ~SER_RS485_RTS_AFTER_SEND;
dev_warn_ratelimited(port->dev, - "%s (%d): invalid RTS setting, using RTS_ON_SEND instead\n", + "%s (%u): invalid RTS setting, using RTS_ON_SEND instead\n", port->name, port->line); } else { rs485->flags |= SER_RS485_RTS_AFTER_SEND; rs485->flags &= ~SER_RS485_RTS_ON_SEND;
dev_warn_ratelimited(port->dev, - "%s (%d): invalid RTS setting, using RTS_AFTER_SEND instead\n", + "%s (%u): invalid RTS setting, using RTS_AFTER_SEND instead\n", port->name, port->line); } } @@ -1850,7 +1850,7 @@ static void uart_wait_until_sent(struct tty_struct *tty, int timeout)
expire = jiffies + timeout;
- pr_debug("uart_wait_until_sent(%d), jiffies=%lu, expire=%lu...\n", + pr_debug("uart_wait_until_sent(%u), jiffies=%lu, expire=%lu...\n", port->line, jiffies, expire);
/* @@ -2046,7 +2046,7 @@ static void uart_line_info(struct seq_file *m, struct uart_driver *drv, int i) return;
mmio = uport->iotype >= UPIO_MEM; - seq_printf(m, "%d: uart:%s %s%08llX irq:%d", + seq_printf(m, "%u: uart:%s %s%08llX irq:%u", uport->line, uart_type(uport), mmio ? "mmio:0x" : "port:", mmio ? (unsigned long long)uport->mapbase @@ -2068,18 +2068,18 @@ static void uart_line_info(struct seq_file *m, struct uart_driver *drv, int i) if (pm_state != UART_PM_STATE_ON) uart_change_pm(state, pm_state);
- seq_printf(m, " tx:%d rx:%d", + seq_printf(m, " tx:%u rx:%u", uport->icount.tx, uport->icount.rx); if (uport->icount.frame) - seq_printf(m, " fe:%d", uport->icount.frame); + seq_printf(m, " fe:%u", uport->icount.frame); if (uport->icount.parity) - seq_printf(m, " pe:%d", uport->icount.parity); + seq_printf(m, " pe:%u", uport->icount.parity); if (uport->icount.brk) - seq_printf(m, " brk:%d", uport->icount.brk); + seq_printf(m, " brk:%u", uport->icount.brk); if (uport->icount.overrun) - seq_printf(m, " oe:%d", uport->icount.overrun); + seq_printf(m, " oe:%u", uport->icount.overrun); if (uport->icount.buf_overrun) - seq_printf(m, " bo:%d", uport->icount.buf_overrun); + seq_printf(m, " bo:%u", uport->icount.buf_overrun);
#define INFOBIT(bit, str) \ if (uport->mctrl & (bit)) \ @@ -2571,7 +2571,7 @@ uart_report_port(struct uart_driver *drv, struct uart_port *port) break; }
- pr_info("%s%s%s at %s (irq = %d, base_baud = %d) is a %s\n", + pr_info("%s%s%s at %s (irq = %u, base_baud = %u) is a %s\n", port->dev ? dev_name(port->dev) : "", port->dev ? ": " : "", port->name, @@ -2579,7 +2579,7 @@ uart_report_port(struct uart_driver *drv, struct uart_port *port)
/* The magic multiplier feature is a bit obscure, so report it too. */ if (port->flags & UPF_MAGIC_MULTIPLIER) - pr_info("%s%s%s extra baud rates supported: %d, %d", + pr_info("%s%s%s extra baud rates supported: %u, %u", port->dev ? dev_name(port->dev) : "", port->dev ? ": " : "", port->name, @@ -2978,7 +2978,7 @@ static ssize_t close_delay_show(struct device *dev, struct tty_port *port = dev_get_drvdata(dev);
uart_get_info(port, &tmp); - return sprintf(buf, "%d\n", tmp.close_delay); + return sprintf(buf, "%u\n", tmp.close_delay); }
static ssize_t closing_wait_show(struct device *dev, @@ -2988,7 +2988,7 @@ static ssize_t closing_wait_show(struct device *dev, struct tty_port *port = dev_get_drvdata(dev);
uart_get_info(port, &tmp); - return sprintf(buf, "%d\n", tmp.closing_wait); + return sprintf(buf, "%u\n", tmp.closing_wait); }
static ssize_t custom_divisor_show(struct device *dev, @@ -3008,7 +3008,7 @@ static ssize_t io_type_show(struct device *dev, struct tty_port *port = dev_get_drvdata(dev);
uart_get_info(port, &tmp); - return sprintf(buf, "%d\n", tmp.io_type); + return sprintf(buf, "%u\n", tmp.io_type); }
static ssize_t iomem_base_show(struct device *dev, @@ -3028,7 +3028,7 @@ static ssize_t iomem_reg_shift_show(struct device *dev, struct tty_port *port = dev_get_drvdata(dev);
uart_get_info(port, &tmp); - return sprintf(buf, "%d\n", tmp.iomem_reg_shift); + return sprintf(buf, "%u\n", tmp.iomem_reg_shift); }
static ssize_t console_show(struct device *dev, @@ -3168,7 +3168,7 @@ static int serial_core_add_one_port(struct uart_driver *drv, struct uart_port *u state->pm_state = UART_PM_STATE_UNDEFINED; uart_port_set_cons(uport, drv->cons); uport->minor = drv->tty_driver->minor_start + uport->line; - uport->name = kasprintf(GFP_KERNEL, "%s%d", drv->dev_name, + uport->name = kasprintf(GFP_KERNEL, "%s%u", drv->dev_name, drv->tty_driver->name_base + uport->line); if (!uport->name) { ret = -ENOMEM; @@ -3211,7 +3211,7 @@ static int serial_core_add_one_port(struct uart_driver *drv, struct uart_port *u device_set_wakeup_capable(tty_dev, 1); } else { uport->flags |= UPF_DEAD; - dev_err(uport->dev, "Cannot register tty device on line %d\n", + dev_err(uport->dev, "Cannot register tty device on line %u\n", uport->line); }