From 07d410e06463f3c1c106e2bb2a7ff23eff1e71c9 Mon Sep 17 00:00:00 2001 From: Qipan Li Date: Mon, 26 May 2014 19:02:07 +0800 Subject: 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.h | 2 -- 1 file changed, 2 deletions(-) (limited to 'drivers/tty/serial/sirfsoc_uart.h') 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; -- cgit