From 50d1e7d1077b276e8faa9eebf8b710edf31fdeea Mon Sep 17 00:00:00 2001 From: Dmitry Eremin-Solenikov Date: Wed, 26 Nov 2014 12:21:56 +0300 Subject: [PATCH] serial: pxa: hold port.lock when reporting modem line changes Both uart_handle_dcd_change() and uart_handle_cts_change() require a port lock to be held and will emit a warning when lockdep is enabled. Held corresponding lock. This fixes the following warnings: ------------[ cut here ]------------ WARNING: CPU: 0 PID: 0 at drivers/tty/serial/serial_core.c:2760 uart_handle_dcd_change+0xc8/0xf8() Modules linked in: CPU: 0 PID: 0 Comm: swapper Not tainted 3.18.0-rc5+ #26 [] (unwind_backtrace) from [] (show_stack+0x10/0x14) [] (show_stack) from [] (warn_slowpath_common+0x6c/0x8c) [] (warn_slowpath_common) from [] (warn_slowpath_null+0x1c/0x24) [] (warn_slowpath_null) from [] (uart_handle_dcd_change+0xc8/0xf8) [] (uart_handle_dcd_change) from [] (serial_pxa_irq+0x268/0x3b0) [] (serial_pxa_irq) from [] (handle_irq_event_percpu+0x50/0x16c) [] (handle_irq_event_percpu) from [] (handle_irq_event+0x3c/0x5c) [] (handle_irq_event) from [] (handle_level_irq+0x94/0x118) [] (handle_level_irq) from [] (generic_handle_irq+0x20/0x30) [] (generic_handle_irq) from [] (__handle_domain_irq+0x38/0x70) [] (__handle_domain_irq) from [] (ichp_handle_irq+0x24/0x34) [] (ichp_handle_irq) from [] (__irq_svc+0x44/0x54) Exception stack(0xc07c7f58 to 0xc07c7fa0) 7f40: 00000001 00000001 7f60: 00000000 20000013 c07c6000 00000000 00000000 c07ce0a4 c07d7798 00000000 7f80: c07e8fb8 0000004c 00000000 c07c7fa0 c0044798 c0009f20 20000013 ffffffff [] (__irq_svc) from [] (arch_cpu_idle+0x28/0x38) [] (arch_cpu_idle) from [] (cpu_startup_entry+0x1b8/0x220) [] (cpu_startup_entry) from [] (start_kernel+0x39c/0x40c) ---[ end trace 4c1b7ae03f6d9d30 ]--- ------------[ cut here ]------------ WARNING: CPU: 0 PID: 0 at drivers/tty/serial/serial_core.c:2791 uart_handle_cts_change+0xa0/0xdc() Modules linked in: CPU: 0 PID: 0 Comm: swapper Tainted: G W 3.18.0-rc5+ #26 [] (unwind_backtrace) from [] (show_stack+0x10/0x14) [] (show_stack) from [] (warn_slowpath_common+0x6c/0x8c) [] (warn_slowpath_common) from [] (warn_slowpath_null+0x1c/0x24) [] (warn_slowpath_null) from [] (uart_handle_cts_change+0xa0/0xdc) [] (uart_handle_cts_change) from [] (serial_pxa_irq+0x258/0x3b0) [] (serial_pxa_irq) from [] (handle_irq_event_percpu+0x50/0x16c) [] (handle_irq_event_percpu) from [] (handle_irq_event+0x3c/0x5c) [] (handle_irq_event) from [] (handle_level_irq+0x94/0x118) [] (handle_level_irq) from [] (generic_handle_irq+0x20/0x30) [] (generic_handle_irq) from [] (__handle_domain_irq+0x38/0x70) [] (__handle_domain_irq) from [] (ichp_handle_irq+0x24/0x34) [] (ichp_handle_irq) from [] (__irq_svc+0x44/0x54) Exception stack(0xc07c7f58 to 0xc07c7fa0) 7f40: 00000001 00000001 7f60: 00000000 20000013 c07c6000 00000000 00000000 c07ce0a4 c07d7798 00000000 7f80: c07e8fb8 0000004c 00000000 c07c7fa0 c0044798 c0009f20 20000013 ffffffff [] (__irq_svc) from [] (arch_cpu_idle+0x28/0x38) [] (arch_cpu_idle) from [] (cpu_startup_entry+0x1b8/0x220) [] (cpu_startup_entry) from [] (start_kernel+0x39c/0x40c) ---[ end trace 4c1b7ae03f6d9d31 ]--- Signed-off-by: Dmitry Eremin-Solenikov Acked-by: Robert Jarzmik Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/pxa.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/tty/serial/pxa.c b/drivers/tty/serial/pxa.c index 21b7d8b86493..7788d53281a0 100644 --- a/drivers/tty/serial/pxa.c +++ b/drivers/tty/serial/pxa.c @@ -223,6 +223,7 @@ static void serial_pxa_start_tx(struct uart_port *port) } } +/* should hold up->port.lock */ static inline void check_modem_status(struct uart_pxa_port *up) { int status; @@ -255,12 +256,14 @@ static inline irqreturn_t serial_pxa_irq(int irq, void *dev_id) iir = serial_in(up, UART_IIR); if (iir & UART_IIR_NO_INT) return IRQ_NONE; + spin_lock(&up->port.lock); lsr = serial_in(up, UART_LSR); if (lsr & UART_LSR_DR) receive_chars(up, &lsr); check_modem_status(up); if (lsr & UART_LSR_THRE) transmit_chars(up); + spin_unlock(&up->port.lock); return IRQ_HANDLED; }