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Commit 7abf9636 authored by Chandana Kishori Chiluveru's avatar Chandana Kishori Chiluveru
Browse files

serial: msm_geni_serial: Do not drop port->lock in polling mode 



In issue case process x already locked uport->lock, whereas process y
trying to unlock same lock. This is resulting in invalid owner spin_bug.

To fix this issue added changes in driver to unlock and lock only
for the interrupt context.

Change-Id: Ifb174a11fc8dce111d0ee7c8bf3efd0e56d084f6
Signed-off-by: default avatarChandana Kishori Chiluveru <cchiluve@codeaurora.org>
parent 1526c9c6

drivers/tty/serial/msm_geni_serial.c

+28 −40
Original line number Diff line number Diff line
@@ -172,8 +172,7 @@ struct msm_geni_serial_port { 
			unsigned int rx_fifo_wc,

			unsigned int rx_last_byte_valid,

			unsigned int rx_last,

			bool drop_rx,

			unsigned long *flags);

			bool drop_rx);

	struct device *wrapper_dev;

	struct se_geni_rsc serial_rsc;

	dma_addr_t tx_dma;
@@ -213,12 +212,12 @@ static int handle_rx_console(struct uart_port *uport, 
			unsigned int rx_fifo_wc,

			unsigned int rx_last_byte_valid,

			unsigned int rx_last,

			bool drop_rx, unsigned long *flags);

			bool drop_rx);

static int handle_rx_hs(struct uart_port *uport,

			unsigned int rx_fifo_wc,

			unsigned int rx_last_byte_valid,

			unsigned int rx_last,

			bool drop_rx, unsigned long *flags);

			bool drop_rx);

static unsigned int msm_geni_serial_tx_empty(struct uart_port *port);

static int msm_geni_serial_power_on(struct uart_port *uport);

static void msm_geni_serial_power_off(struct uart_port *uport);
@@ -238,7 +237,7 @@ static int uart_line_id; 
static struct msm_geni_serial_port msm_geni_console_port;

static struct msm_geni_serial_port msm_geni_serial_ports[GENI_UART_NR_PORTS];

static void msm_geni_serial_handle_isr(struct uart_port *uport,

				unsigned long *flags);

				unsigned long *flags, bool is_irq_masked);



/*

 * The below API is required to check if uport->lock (spinlock)
@@ -351,7 +350,6 @@ bool geni_wait_for_cmd_done(struct uart_port *uport, bool is_irq_masked) 
{

	struct msm_geni_serial_port *msm_port = GET_DEV_PORT(uport);

	unsigned long timeout = POLL_ITERATIONS;

	unsigned long ret;

	unsigned long flags = 0;



	/*
@@ -366,13 +364,13 @@ bool geni_wait_for_cmd_done(struct uart_port *uport, bool is_irq_masked) 
		 */

		if (msm_port->m_cmd) {

			while (!msm_port->m_cmd_done && timeout > 0) {

				msm_geni_serial_handle_isr(uport, &flags);

				msm_geni_serial_handle_isr(uport, &flags, true);

				timeout--;

				udelay(100);

			}

		} else if (msm_port->s_cmd) {

			while (!msm_port->s_cmd_done && timeout > 0) {

				msm_geni_serial_handle_isr(uport, &flags);

				msm_geni_serial_handle_isr(uport, &flags, true);

				timeout--;

				udelay(100);

			}
@@ -380,16 +378,16 @@ bool geni_wait_for_cmd_done(struct uart_port *uport, bool is_irq_masked) 
	} else {

		/* Waiting for 10 milli second for interrupt to be fired */

		if (msm_port->m_cmd)

			ret = wait_for_completion_timeout

			timeout = wait_for_completion_timeout

					(&msm_port->m_cmd_timeout,

				msecs_to_jiffies(POLL_WAIT_TIMEOUT_MSEC));

		else if (msm_port->s_cmd)

			ret = wait_for_completion_timeout

			timeout = wait_for_completion_timeout

					(&msm_port->s_cmd_timeout,

				msecs_to_jiffies(POLL_WAIT_TIMEOUT_MSEC));

	}



	return ret ? 0 : 1;

	return timeout ? 0 : 1;

}



static void msm_geni_serial_config_port(struct uart_port *uport, int cfg_flags)
@@ -1033,13 +1031,12 @@ static int handle_rx_console(struct uart_port *uport, 
			unsigned int rx_fifo_wc,

			unsigned int rx_last_byte_valid,

			unsigned int rx_last,

			bool drop_rx, unsigned long *flags)

			bool drop_rx)

{

	int i, c;

	unsigned char *rx_char;

	struct tty_port *tport;

	struct msm_geni_serial_port *msm_port = GET_DEV_PORT(uport);

	bool locked;



	tport = &uport->state->port;

	for (i = 0; i < rx_fifo_wc; i++) {
@@ -1065,23 +1062,6 @@ static int handle_rx_console(struct uart_port *uport, 
				tty_insert_flip_char(tport, rx_char[c], flag);

		}

	}

	if (!drop_rx) {

		/*

		 * Driver acquiring port->lock in isr function and calling

		 * tty_flip_buffer_push() which in turn will wait for

		 * another lock from framework __queue_work function.

		 * release the port lock before calling tty_flip_buffer_push()

		 * to avoid deadlock scenarios.

		 */

		locked = msm_geni_serial_spinlocked(uport);

		if (locked) {

			spin_unlock_irqrestore(&uport->lock, *flags);

			tty_flip_buffer_push(tport);

			spin_lock_irqsave(&uport->lock, *flags);

		} else {

			tty_flip_buffer_push(tport);

		}

	}

	return 0;

}

#else
@@ -1089,7 +1069,7 @@ static int handle_rx_console(struct uart_port *uport, 
			unsigned int rx_fifo_wc,

			unsigned int rx_last_byte_valid,

			unsigned int rx_last,

			bool drop_rx, unsigned long *flags)

			bool drop_rx)

{

	return -EPERM;

}
@@ -1520,7 +1500,7 @@ static void stop_rx_sequencer(struct uart_port *uport) 
			    "%s cancel failed is_rx_active:%d 0x%x\n",

			    __func__, is_rx_active, geni_status);

		if (uart_console(uport) && !is_rx_active) {

			msm_geni_serial_handle_isr(uport, &flags);

			msm_geni_serial_handle_isr(uport, &flags, true);

			goto exit_rx_seq;

		}

		port->s_cmd_done = false;
@@ -1568,7 +1548,7 @@ static int handle_rx_hs(struct uart_port *uport, 
			unsigned int rx_fifo_wc,

			unsigned int rx_last_byte_valid,

			unsigned int rx_last,

			bool drop_rx, unsigned long *flags)

			bool drop_rx)

{

	unsigned char *rx_char;

	struct tty_port *tport;
@@ -1600,8 +1580,7 @@ static int handle_rx_hs(struct uart_port *uport, 
	return ret;

}



static int msm_geni_serial_handle_rx(struct uart_port *uport, bool drop_rx,

				     unsigned long *flags)

static int msm_geni_serial_handle_rx(struct uart_port *uport, bool drop_rx)

{

	int ret = 0;

	unsigned int rx_fifo_status;
@@ -1620,7 +1599,7 @@ static int msm_geni_serial_handle_rx(struct uart_port *uport, bool drop_rx, 
	rx_last = rx_fifo_status & RX_LAST;

	if (rx_fifo_wc)

		ret = port->handle_rx(uport, rx_fifo_wc, rx_last_byte_valid,

						rx_last, drop_rx, flags);

						rx_last, drop_rx);

	return ret;

}
@@ -1803,7 +1782,8 @@ static int msm_geni_serial_handle_dma_tx(struct uart_port *uport) 
}



static void msm_geni_serial_handle_isr(struct uart_port *uport,

				       unsigned long *flags)

				       unsigned long *flags,

				       bool is_irq_masked)

{

	unsigned int m_irq_status;

	unsigned int s_irq_status;
@@ -1889,8 +1869,16 @@ static void msm_geni_serial_handle_isr(struct uart_port *uport, 
		}



		if (s_irq_status & (S_RX_FIFO_WATERMARK_EN |

							S_RX_FIFO_LAST_EN))

			msm_geni_serial_handle_rx(uport, drop_rx, flags);

							S_RX_FIFO_LAST_EN)) {

			msm_geni_serial_handle_rx(uport, drop_rx);

			if (!drop_rx && !is_irq_masked) {

				spin_unlock_irqrestore(&uport->lock, *flags);

				tty_flip_buffer_push(tport);

				spin_lock_irqsave(&uport->lock, *flags);

			} else if (!drop_rx) {

				tty_flip_buffer_push(tport);

			}

		}

	} else {

		dma_tx_status = geni_read_reg_nolog(uport->membase,

							SE_DMA_TX_IRQ_STAT);
@@ -1984,7 +1972,7 @@ static irqreturn_t msm_geni_serial_isr(int isr, void *dev) 
	unsigned long flags;



	spin_lock_irqsave(&uport->lock, flags);

	msm_geni_serial_handle_isr(uport, &flags);

	msm_geni_serial_handle_isr(uport, &flags, false);

	spin_unlock_irqrestore(&uport->lock, flags);

	return IRQ_HANDLED;

}