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serial: sirf: fix spinlock deadlock issue
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commit 07d410e upstream.

commit fb78b81 provide a workaround for
kernel panic, but bring potential deadlock risk. that is in
sirfsoc_rx_tmo_process_tl while enter into sirfsoc_uart_pio_rx_chars
cpu hold uart_port->lock, if uart interrupt comes cpu enter into
sirfsoc_uart_isr and deadlock occurs in getting uart_port->lock.

the patch replace spin_lock version to spin_lock_irq* version to avoid
spinlock dead lock issue. let function tty_flip_buffer_push in tasklet
outof spin_lock_irq* protect area to avoid add the pair of spin_lock and
spin_unlock for tty_flip_buffer_push.
BTW drop self defined unused spinlock protect of tx_lock/rx_lock.

56274.220464] BUG: spinlock lockup suspected on CPU#0, swapper/0/0
[56274.223648]  lock: 0xc05d9db0, .magic: dead4ead, .owner: swapper/0/0,
	.owner_cpu: 0
	[56274.231278] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G
	O 3.10.35 #1
	[56274.238241] [<c0015530>] (unwind_backtrace+0x0/0xf4) from
	[<c00120d8>] (show_stack+0x10/0x14)
	[56274.246742] [<c00120d8>] (show_stack+0x10/0x14) from
	[<c01b11b0>] (do_raw_spin_lock+0x110/0x184)
	[56274.255501] [<c01b11b0>] (do_raw_spin_lock+0x110/0x184) from
	[<c02124c8>] (sirfsoc_uart_isr+0x20/0x42c)
	[56274.264874] [<c02124c8>] (sirfsoc_uart_isr+0x20/0x42c) from
	[<c0075790>] (handle_irq_event_percpu+0x54/0x17c)
	[56274.274758] [<c0075790>] (handle_irq_event_percpu+0x54/0x17c)
	from [<c00758f4>] (handle_irq_event+0x3c/0x5c)
	[56274.284561] [<c00758f4>] (handle_irq_event+0x3c/0x5c) from
	[<c0077fa0>] (handle_level_irq+0x98/0xfc)
	[56274.293670] [<c0077fa0>] (handle_level_irq+0x98/0xfc) from
	[<c0074f44>] (generic_handle_irq+0x2c/0x3c)
	[56274.302952] [<c0074f44>] (generic_handle_irq+0x2c/0x3c) from
	[<c000ef80>] (handle_IRQ+0x40/0x90)
	[56274.311706] [<c000ef80>] (handle_IRQ+0x40/0x90) from
	[<c000dc80>] (__irq_svc+0x40/0x70)
	[56274.319697] [<c000dc80>] (__irq_svc+0x40/0x70) from
	[<c038113c>] (_raw_spin_unlock_irqrestore+0x10/0x48)
	[56274.329158] [<c038113c>]
	(_raw_spin_unlock_irqrestore+0x10/0x48) from [<c0200034>]
	(tty_port_tty_get+0x58/0x90)
	[56274.339213] [<c0200034>] (tty_port_tty_get+0x58/0x90) from
	[<c0212008>] (sirfsoc_uart_pio_rx_chars+0x1c/0xc8)
	[56274.349097] [<c0212008>]
	(sirfsoc_uart_pio_rx_chars+0x1c/0xc8) from [<c0212ef8>]
	(sirfsoc_rx_tmo_process_tl+0xe4/0x1fc)
	[56274.359853] [<c0212ef8>]
	(sirfsoc_rx_tmo_process_tl+0xe4/0x1fc) from [<c0027c04>]
	(tasklet_action+0x84/0x114)
	[56274.369739] [<c0027c04>] (tasklet_action+0x84/0x114) from
	[<c0027db4>] (__do_softirq+0x120/0x200)
	[56274.378585] [<c0027db4>] (__do_softirq+0x120/0x200) from
	[<c0027f44>] (do_softirq+0x54/0x5c)
	[56274.386998] [<c0027f44>] (do_softirq+0x54/0x5c) from
	[<c00281ec>] (irq_exit+0x9c/0xd0)
	[56274.394899] [<c00281ec>] (irq_exit+0x9c/0xd0) from
	[<c000ef84>] (handle_IRQ+0x44/0x90)
	[56274.402790] [<c000ef84>] (handle_IRQ+0x44/0x90) from
	[<c000dc80>] (__irq_svc+0x40/0x70)
	[56274.410774] [<c000dc80>] (__irq_svc+0x40/0x70) from
	[<c0288af4>] (cpuidle_enter_state+0x50/0xe0)
	[56274.419532] [<c0288af4>] (cpuidle_enter_state+0x50/0xe0) from
	[<c0288c34>] (cpuidle_idle_call+0xb0/0x148)
	[56274.429080] [<c0288c34>] (cpuidle_idle_call+0xb0/0x148) from
	[<c000f3ac>] (arch_cpu_idle+0x8/0x38)
	[56274.438016] [<c000f3ac>] (arch_cpu_idle+0x8/0x38) from
	[<c0059344>] (cpu_startup_entry+0xfc/0x140)
	[56274.446956] [<c0059344>] (cpu_startup_entry+0xfc/0x140) from
	[<c04a3a54>] (start_kernel+0x2d8/0x2e4)

Signed-off-by: Qipan Li <Qipan.Li@csr.com>
Signed-off-by: Barry Song <Baohua.Song@csr.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
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Qipan Li authored and Jiri Slaby committed Jul 28, 2014
1 parent 9b44862 commit 67aedbd
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Showing 2 changed files with 18 additions and 33 deletions.
49 changes: 18 additions & 31 deletions drivers/tty/serial/sirfsoc_uart.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -359,9 +359,11 @@ static irqreturn_t sirfsoc_uart_usp_cts_handler(int irq, void *dev_id)
{
struct sirfsoc_uart_port *sirfport = (struct sirfsoc_uart_port *)dev_id;
struct uart_port *port = &sirfport->port;
spin_lock(&port->lock);
if (gpio_is_valid(sirfport->cts_gpio) && sirfport->ms_enabled)
uart_handle_cts_change(port,
!gpio_get_value(sirfport->cts_gpio));
spin_unlock(&port->lock);
return IRQ_HANDLED;
}

Expand Down Expand Up @@ -429,10 +431,6 @@ sirfsoc_uart_pio_rx_chars(struct uart_port *port, unsigned int max_rx_count)
sirfport->rx_io_count += rx_count;
port->icount.rx += rx_count;

spin_unlock(&port->lock);
tty_flip_buffer_push(&port->state->port);
spin_lock(&port->lock);

return rx_count;
}

Expand Down Expand Up @@ -466,6 +464,7 @@ static void sirfsoc_uart_tx_dma_complete_callback(void *param)
struct circ_buf *xmit = &port->state->xmit;
unsigned long flags;

spin_lock_irqsave(&port->lock, flags);
xmit->tail = (xmit->tail + sirfport->transfer_size) &
(UART_XMIT_SIZE - 1);
port->icount.tx += sirfport->transfer_size;
Expand All @@ -474,10 +473,9 @@ static void sirfsoc_uart_tx_dma_complete_callback(void *param)
if (sirfport->tx_dma_addr)
dma_unmap_single(port->dev, sirfport->tx_dma_addr,
sirfport->transfer_size, DMA_TO_DEVICE);
spin_lock_irqsave(&sirfport->tx_lock, flags);
sirfport->tx_dma_state = TX_DMA_IDLE;
sirfsoc_uart_tx_with_dma(sirfport);
spin_unlock_irqrestore(&sirfport->tx_lock, flags);
spin_unlock_irqrestore(&port->lock, flags);
}

static void sirfsoc_uart_insert_rx_buf_to_tty(
Expand All @@ -490,7 +488,6 @@ static void sirfsoc_uart_insert_rx_buf_to_tty(
inserted = tty_insert_flip_string(tport,
sirfport->rx_dma_items[sirfport->rx_completed].xmit.buf, count);
port->icount.rx += inserted;
tty_flip_buffer_push(tport);
}

static void sirfsoc_rx_submit_one_dma_desc(struct uart_port *port, int index)
Expand Down Expand Up @@ -525,7 +522,7 @@ static void sirfsoc_rx_tmo_process_tl(unsigned long param)
unsigned int count;
unsigned long flags;

spin_lock_irqsave(&sirfport->rx_lock, flags);
spin_lock_irqsave(&port->lock, flags);
while (sirfport->rx_completed != sirfport->rx_issued) {
sirfsoc_uart_insert_rx_buf_to_tty(sirfport,
SIRFSOC_RX_DMA_BUF_SIZE);
Expand All @@ -540,12 +537,8 @@ static void sirfsoc_rx_tmo_process_tl(unsigned long param)
wr_regl(port, ureg->sirfsoc_rx_dma_io_ctrl,
rd_regl(port, ureg->sirfsoc_rx_dma_io_ctrl) |
SIRFUART_IO_MODE);
spin_unlock_irqrestore(&sirfport->rx_lock, flags);
spin_lock(&port->lock);
sirfsoc_uart_pio_rx_chars(port, 4 - sirfport->rx_io_count);
spin_unlock(&port->lock);
if (sirfport->rx_io_count == 4) {
spin_lock_irqsave(&sirfport->rx_lock, flags);
sirfport->rx_io_count = 0;
wr_regl(port, ureg->sirfsoc_int_st_reg,
uint_st->sirfsoc_rx_done);
Expand All @@ -556,11 +549,8 @@ static void sirfsoc_rx_tmo_process_tl(unsigned long param)
else
wr_regl(port, SIRFUART_INT_EN_CLR,
uint_en->sirfsoc_rx_done_en);
spin_unlock_irqrestore(&sirfport->rx_lock, flags);

sirfsoc_uart_start_next_rx_dma(port);
} else {
spin_lock_irqsave(&sirfport->rx_lock, flags);
wr_regl(port, ureg->sirfsoc_int_st_reg,
uint_st->sirfsoc_rx_done);
if (!sirfport->is_marco)
Expand All @@ -570,8 +560,9 @@ static void sirfsoc_rx_tmo_process_tl(unsigned long param)
else
wr_regl(port, ureg->sirfsoc_int_en_reg,
uint_en->sirfsoc_rx_done_en);
spin_unlock_irqrestore(&sirfport->rx_lock, flags);
}
spin_unlock_irqrestore(&port->lock, flags);
tty_flip_buffer_push(&port->state->port);
}

static void sirfsoc_uart_handle_rx_tmo(struct sirfsoc_uart_port *sirfport)
Expand All @@ -580,8 +571,6 @@ static void sirfsoc_uart_handle_rx_tmo(struct sirfsoc_uart_port *sirfport)
struct sirfsoc_register *ureg = &sirfport->uart_reg->uart_reg;
struct sirfsoc_int_en *uint_en = &sirfport->uart_reg->uart_int_en;
struct dma_tx_state tx_state;
spin_lock(&sirfport->rx_lock);

dmaengine_tx_status(sirfport->rx_dma_chan,
sirfport->rx_dma_items[sirfport->rx_issued].cookie, &tx_state);
dmaengine_terminate_all(sirfport->rx_dma_chan);
Expand All @@ -594,7 +583,6 @@ static void sirfsoc_uart_handle_rx_tmo(struct sirfsoc_uart_port *sirfport)
else
wr_regl(port, SIRFUART_INT_EN_CLR,
uint_en->sirfsoc_rx_timeout_en);
spin_unlock(&sirfport->rx_lock);
tasklet_schedule(&sirfport->rx_tmo_process_tasklet);
}

Expand Down Expand Up @@ -658,7 +646,6 @@ static irqreturn_t sirfsoc_uart_isr(int irq, void *dev_id)
intr_status &= port->read_status_mask;
uart_insert_char(port, intr_status,
uint_en->sirfsoc_rx_oflow_en, 0, flag);
tty_flip_buffer_push(&state->port);
}
recv_char:
if ((sirfport->uart_reg->uart_type == SIRF_REAL_UART) &&
Expand All @@ -683,6 +670,9 @@ static irqreturn_t sirfsoc_uart_isr(int irq, void *dev_id)
sirfsoc_uart_pio_rx_chars(port,
SIRFSOC_UART_IO_RX_MAX_CNT);
}
spin_unlock(&port->lock);
tty_flip_buffer_push(&state->port);
spin_lock(&port->lock);
if (intr_status & uint_st->sirfsoc_txfifo_empty) {
if (IS_DMA_CHAN_VALID(sirfport->tx_dma_no))
sirfsoc_uart_tx_with_dma(sirfport);
Expand All @@ -701,6 +691,7 @@ static irqreturn_t sirfsoc_uart_isr(int irq, void *dev_id)
}
}
spin_unlock(&port->lock);

return IRQ_HANDLED;
}

Expand All @@ -709,24 +700,27 @@ static void sirfsoc_uart_rx_dma_complete_tl(unsigned long param)
struct sirfsoc_uart_port *sirfport = (struct sirfsoc_uart_port *)param;
struct uart_port *port = &sirfport->port;
unsigned long flags;
spin_lock_irqsave(&sirfport->rx_lock, flags);
spin_lock_irqsave(&port->rx_lock, flags);
while (sirfport->rx_completed != sirfport->rx_issued) {
sirfsoc_uart_insert_rx_buf_to_tty(sirfport,
SIRFSOC_RX_DMA_BUF_SIZE);
sirfsoc_rx_submit_one_dma_desc(port, sirfport->rx_completed++);
sirfport->rx_completed %= SIRFSOC_RX_LOOP_BUF_CNT;
}
spin_unlock_irqrestore(&sirfport->rx_lock, flags);
spin_unlock_irqrestore(&port->lock, flags);
tty_flip_buffer_push(&port->state->port);
}

static void sirfsoc_uart_rx_dma_complete_callback(void *param)
{
struct sirfsoc_uart_port *sirfport = (struct sirfsoc_uart_port *)param;
spin_lock(&sirfport->rx_lock);
unsigned long flags;

spin_lock_irqsave(&sirfport->port.lock, flags);
sirfport->rx_issued++;
sirfport->rx_issued %= SIRFSOC_RX_LOOP_BUF_CNT;
spin_unlock(&sirfport->rx_lock);
tasklet_schedule(&sirfport->rx_dma_complete_tasklet);
spin_unlock_irqrestore(&sirfport->port.lock, flags);
}

/* submit rx dma task into dmaengine */
Expand All @@ -735,26 +729,21 @@ static void sirfsoc_uart_start_next_rx_dma(struct uart_port *port)
struct sirfsoc_uart_port *sirfport = to_sirfport(port);
struct sirfsoc_register *ureg = &sirfport->uart_reg->uart_reg;
struct sirfsoc_int_en *uint_en = &sirfport->uart_reg->uart_int_en;
unsigned long flags;
int i;
spin_lock_irqsave(&sirfport->rx_lock, flags);
sirfport->rx_io_count = 0;
wr_regl(port, ureg->sirfsoc_rx_dma_io_ctrl,
rd_regl(port, ureg->sirfsoc_rx_dma_io_ctrl) &
~SIRFUART_IO_MODE);
spin_unlock_irqrestore(&sirfport->rx_lock, flags);
for (i = 0; i < SIRFSOC_RX_LOOP_BUF_CNT; i++)
sirfsoc_rx_submit_one_dma_desc(port, i);
sirfport->rx_completed = sirfport->rx_issued = 0;
spin_lock_irqsave(&sirfport->rx_lock, flags);
if (!sirfport->is_marco)
wr_regl(port, ureg->sirfsoc_int_en_reg,
rd_regl(port, ureg->sirfsoc_int_en_reg) |
SIRFUART_RX_DMA_INT_EN(port, uint_en));
else
wr_regl(port, ureg->sirfsoc_int_en_reg,
SIRFUART_RX_DMA_INT_EN(port, uint_en));
spin_unlock_irqrestore(&sirfport->rx_lock, flags);
}

static void sirfsoc_uart_start_rx(struct uart_port *port)
Expand Down Expand Up @@ -1455,8 +1444,6 @@ static int sirfsoc_uart_probe(struct platform_device *pdev)
ret = -EFAULT;
goto err;
}
spin_lock_init(&sirfport->rx_lock);
spin_lock_init(&sirfport->tx_lock);
tasklet_init(&sirfport->rx_dma_complete_tasklet,
sirfsoc_uart_rx_dma_complete_tl, (unsigned long)sirfport);
tasklet_init(&sirfport->rx_tmo_process_tasklet,
Expand Down
2 changes: 0 additions & 2 deletions drivers/tty/serial/sirfsoc_uart.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -438,8 +438,6 @@ struct sirfsoc_uart_port {
struct dma_chan *tx_dma_chan;
dma_addr_t tx_dma_addr;
struct dma_async_tx_descriptor *tx_dma_desc;
spinlock_t rx_lock;
spinlock_t tx_lock;
struct tasklet_struct rx_dma_complete_tasklet;
struct tasklet_struct rx_tmo_process_tasklet;
unsigned int rx_io_count;
Expand Down

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