From 07d410e06463f3c1c106e2bb2a7ff23eff1e71c9 Mon Sep 17 00:00:00 2001 From: Qipan Li Date: Mon, 26 May 2014 19:02:07 +0800 Subject: [PATCH] serial: sirf: fix spinlock deadlock issue commit fb78b811422cd2d8c8605949cc4cc13618347ad5 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] [] (unwind_backtrace+0x0/0xf4) from [] (show_stack+0x10/0x14) [56274.246742] [] (show_stack+0x10/0x14) from [] (do_raw_spin_lock+0x110/0x184) [56274.255501] [] (do_raw_spin_lock+0x110/0x184) from [] (sirfsoc_uart_isr+0x20/0x42c) [56274.264874] [] (sirfsoc_uart_isr+0x20/0x42c) from [] (handle_irq_event_percpu+0x54/0x17c) [56274.274758] [] (handle_irq_event_percpu+0x54/0x17c) from [] (handle_irq_event+0x3c/0x5c) [56274.284561] [] (handle_irq_event+0x3c/0x5c) from [] (handle_level_irq+0x98/0xfc) [56274.293670] [] (handle_level_irq+0x98/0xfc) from [] (generic_handle_irq+0x2c/0x3c) [56274.302952] [] (generic_handle_irq+0x2c/0x3c) from [] (handle_IRQ+0x40/0x90) [56274.311706] [] (handle_IRQ+0x40/0x90) from [] (__irq_svc+0x40/0x70) [56274.319697] [] (__irq_svc+0x40/0x70) from [] (_raw_spin_unlock_irqrestore+0x10/0x48) [56274.329158] [] (_raw_spin_unlock_irqrestore+0x10/0x48) from [] (tty_port_tty_get+0x58/0x90) [56274.339213] [] (tty_port_tty_get+0x58/0x90) from [] (sirfsoc_uart_pio_rx_chars+0x1c/0xc8) [56274.349097] [] (sirfsoc_uart_pio_rx_chars+0x1c/0xc8) from [] (sirfsoc_rx_tmo_process_tl+0xe4/0x1fc) [56274.359853] [] (sirfsoc_rx_tmo_process_tl+0xe4/0x1fc) from [] (tasklet_action+0x84/0x114) [56274.369739] [] (tasklet_action+0x84/0x114) from [] (__do_softirq+0x120/0x200) [56274.378585] [] (__do_softirq+0x120/0x200) from [] (do_softirq+0x54/0x5c) [56274.386998] [] (do_softirq+0x54/0x5c) from [] (irq_exit+0x9c/0xd0) [56274.394899] [] (irq_exit+0x9c/0xd0) from [] (handle_IRQ+0x44/0x90) [56274.402790] [] (handle_IRQ+0x44/0x90) from [] (__irq_svc+0x40/0x70) [56274.410774] [] (__irq_svc+0x40/0x70) from [] (cpuidle_enter_state+0x50/0xe0) [56274.419532] [] (cpuidle_enter_state+0x50/0xe0) from [] (cpuidle_idle_call+0xb0/0x148) [56274.429080] [] (cpuidle_idle_call+0xb0/0x148) from [] (arch_cpu_idle+0x8/0x38) [56274.438016] [] (arch_cpu_idle+0x8/0x38) from [] (cpu_startup_entry+0xfc/0x140) [56274.446956] [] (cpu_startup_entry+0xfc/0x140) from [] (start_kernel+0x2d8/0x2e4) Signed-off-by: Qipan Li Signed-off-by: Barry Song Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/sirfsoc_uart.c | 49 ++++++++++++------------------- drivers/tty/serial/sirfsoc_uart.h | 2 -- 2 files changed, 18 insertions(+), 33 deletions(-) diff --git a/drivers/tty/serial/sirfsoc_uart.c b/drivers/tty/serial/sirfsoc_uart.c index 845548cf05f8..236f892dab9c 100644 --- a/drivers/tty/serial/sirfsoc_uart.c +++ b/drivers/tty/serial/sirfsoc_uart.c @@ -358,9 +358,11 @@ 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; } @@ -428,10 +430,6 @@ 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; } @@ -465,6 +463,7 @@ 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; @@ -473,10 +472,9 @@ 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( @@ -489,7 +487,6 @@ 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) @@ -525,7 +522,7 @@ static void sirfsoc_rx_tmo_process_tl(unsigned long param) unsigned long flags; struct dma_tx_state tx_state; - spin_lock_irqsave(&sirfport->rx_lock, flags); + spin_lock_irqsave(&port->lock, flags); while (DMA_COMPLETE == dmaengine_tx_status(sirfport->rx_dma_chan, sirfport->rx_dma_items[sirfport->rx_completed].cookie, &tx_state)) { sirfsoc_uart_insert_rx_buf_to_tty(sirfport, @@ -541,12 +538,8 @@ 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); @@ -557,11 +550,8 @@ 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) @@ -571,8 +561,9 @@ 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) @@ -581,8 +572,6 @@ 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); @@ -595,7 +584,6 @@ 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); } @@ -659,7 +647,6 @@ 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) && @@ -684,6 +671,9 @@ recv_char: 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 (sirfport->tx_dma_chan) sirfsoc_uart_tx_with_dma(sirfport); @@ -702,6 +692,7 @@ recv_char: } } spin_unlock(&port->lock); + return IRQ_HANDLED; } @@ -713,7 +704,7 @@ static void sirfsoc_uart_rx_dma_complete_tl(unsigned long param) struct sirfsoc_int_en *uint_en = &sirfport->uart_reg->uart_int_en; unsigned long flags; struct dma_tx_state tx_state; - spin_lock_irqsave(&sirfport->rx_lock, flags); + spin_lock_irqsave(&port->rx_lock, flags); while (DMA_COMPLETE == dmaengine_tx_status(sirfport->rx_dma_chan, sirfport->rx_dma_items[sirfport->rx_completed].cookie, &tx_state)) { sirfsoc_uart_insert_rx_buf_to_tty(sirfport, @@ -726,17 +717,20 @@ static void sirfsoc_uart_rx_dma_complete_tl(unsigned long param) 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 */ @@ -745,18 +739,14 @@ 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) | @@ -764,7 +754,6 @@ static void sirfsoc_uart_start_next_rx_dma(struct uart_port *port) 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) @@ -1369,8 +1358,6 @@ usp_no_flow_control: 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, diff --git a/drivers/tty/serial/sirfsoc_uart.h b/drivers/tty/serial/sirfsoc_uart.h index 4280819e1888..69a62ebd3afc 100644 --- a/drivers/tty/serial/sirfsoc_uart.h +++ b/drivers/tty/serial/sirfsoc_uart.h @@ -424,8 +424,6 @@ 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; -- 2.30.2