From: Stefan Agner Date: Sat, 10 Jan 2015 00:08:58 +0000 (+0100) Subject: serial: fsl_lpuart: delete timer on shutdown X-Git-Tag: firefly_0821_release~176^2~2319^2~60 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=4a8588a1cf867333187d9ff071e6fbdab587d194;p=firefly-linux-kernel-4.4.55.git serial: fsl_lpuart: delete timer on shutdown If the serial port gets closed while a RX transfer is in progress, the timer might fire after the serial port shutdown finished. This leads in a NULL pointer dereference: [ 7.508324] Unable to handle kernel NULL pointer dereference at virtual address 00000000 [ 7.516590] pgd = 86348000 [ 7.519445] [00000000] *pgd=86179831, *pte=00000000, *ppte=00000000 [ 7.526145] Internal error: Oops: 17 [#1] ARM [ 7.530611] Modules linked in: [ 7.533876] CPU: 0 PID: 123 Comm: systemd Not tainted 3.19.0-rc3-00004-g5b11ea7 #1778 [ 7.541827] Hardware name: Freescale Vybrid VF610 (Device Tree) [ 7.547862] task: 861c3400 ti: 86ac8000 task.ti: 86ac8000 [ 7.553392] PC is at lpuart_timer_func+0x24/0xf8 [ 7.558127] LR is at lpuart_timer_func+0x20/0xf8 [ 7.562857] pc : [<802df99c>] lr : [<802df998>] psr: 600b0113 [ 7.562857] sp : 86ac9b90 ip : 86ac9b90 fp : 86ac9bbc [ 7.574467] r10: 80817180 r9 : 80817b98 r8 : 80817998 [ 7.579803] r7 : 807acee0 r6 : 86989000 r5 : 00000100 r4 : 86997210 [ 7.586444] r3 : 86ac8000 r2 : 86ac9bc0 r1 : 86997210 r0 : 00000000 [ 7.593085] Flags: nZCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment user [ 7.600341] Control: 10c5387d Table: 86348059 DAC: 00000015 [ 7.606203] Process systemd (pid: 123, stack limit = 0x86ac8230) Setup the timer on UART startup which allows to delete the timer unconditionally on shutdown. This also saves the initialization on each transfer. Signed-off-by: Stefan Agner Cc: stable # 3.14 Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c index e7cde3a9566d..29932b73c004 100644 --- a/drivers/tty/serial/fsl_lpuart.c +++ b/drivers/tty/serial/fsl_lpuart.c @@ -506,9 +506,6 @@ static inline void lpuart_prepare_rx(struct lpuart_port *sport) spin_lock_irqsave(&sport->port.lock, flags); - init_timer(&sport->lpuart_timer); - sport->lpuart_timer.function = lpuart_timer_func; - sport->lpuart_timer.data = (unsigned long)sport; sport->lpuart_timer.expires = jiffies + sport->dma_rx_timeout; add_timer(&sport->lpuart_timer); @@ -1106,6 +1103,8 @@ static int lpuart_startup(struct uart_port *port) sport->lpuart_dma_use = false; } else { sport->lpuart_dma_use = true; + setup_timer(&sport->lpuart_timer, lpuart_timer_func, + (unsigned long)sport); temp = readb(port->membase + UARTCR5); writeb(temp | UARTCR5_TDMAS, port->membase + UARTCR5); } @@ -1180,6 +1179,8 @@ static void lpuart_shutdown(struct uart_port *port) devm_free_irq(port->dev, port->irq, sport); if (sport->lpuart_dma_use) { + del_timer_sync(&sport->lpuart_timer); + lpuart_dma_tx_free(port); lpuart_dma_rx_free(port); }