diff options
| author | Alexander Sverdlin <alexander.sverdlin@siemens.com> | 2023-03-09 14:43:02 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-03-09 17:09:06 +0100 |
| commit | 1be6f2b15f902c02e055ae0b419ca789200473c9 (patch) | |
| tree | b5322657641c9c8caed7d599e2884e6d4b09afab /drivers/tty/serial/fsl_lpuart.c | |
| parent | 5d943b5d69c032de7ce9cd625ac083a5c277b9c5 (diff) | |
tty: serial: fsl_lpuart: fix race on RX DMA shutdown
From time to time DMA completion can come in the middle of DMA shutdown:
<process ctx>: <IRQ>:
lpuart32_shutdown()
lpuart_dma_shutdown()
del_timer_sync()
lpuart_dma_rx_complete()
lpuart_copy_rx_to_tty()
mod_timer()
lpuart_dma_rx_free()
When the timer fires a bit later, sport->dma_rx_desc is NULL:
Unable to handle kernel NULL pointer dereference at virtual address 0000000000000004
pc : lpuart_copy_rx_to_tty+0xcc/0x5bc
lr : lpuart_timer_func+0x1c/0x2c
Call trace:
lpuart_copy_rx_to_tty
lpuart_timer_func
call_timer_fn
__run_timers.part.0
run_timer_softirq
__do_softirq
__irq_exit_rcu
irq_exit
handle_domain_irq
gic_handle_irq
call_on_irq_stack
do_interrupt_handler
...
To fix this fold del_timer_sync() into lpuart_dma_rx_free() after
dmaengine_terminate_sync() to make sure timer will not be re-started in
lpuart_copy_rx_to_tty() <= lpuart_dma_rx_complete().
Fixes: 4a8588a1cf86 ("serial: fsl_lpuart: delete timer on shutdown")
Cc: stable <stable@kernel.org>
Signed-off-by: Alexander Sverdlin <alexander.sverdlin@siemens.com>
Link: https://lore.kernel.org/r/20230309134302.74940-2-alexander.sverdlin@siemens.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/serial/fsl_lpuart.c')
| -rw-r--r-- | drivers/tty/serial/fsl_lpuart.c | 11 |
1 files changed, 3 insertions, 8 deletions
diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c index f9e164abf920..56e6ba3250cd 100644 --- a/drivers/tty/serial/fsl_lpuart.c +++ b/drivers/tty/serial/fsl_lpuart.c @@ -1354,6 +1354,7 @@ static void lpuart_dma_rx_free(struct uart_port *port) struct dma_chan *chan = sport->dma_rx_chan; dmaengine_terminate_sync(chan); + del_timer_sync(&sport->lpuart_timer); dma_unmap_sg(chan->device->dev, &sport->rx_sgl, 1, DMA_FROM_DEVICE); kfree(sport->rx_ring.buf); sport->rx_ring.tail = 0; @@ -1813,7 +1814,6 @@ static int lpuart32_startup(struct uart_port *port) static void lpuart_dma_shutdown(struct lpuart_port *sport) { if (sport->lpuart_dma_rx_use) { - del_timer_sync(&sport->lpuart_timer); lpuart_dma_rx_free(&sport->port); sport->lpuart_dma_rx_use = false; } @@ -1973,10 +1973,8 @@ lpuart_set_termios(struct uart_port *port, struct ktermios *termios, * Since timer function acqures sport->port.lock, need to stop before * acquring same lock because otherwise del_timer_sync() can deadlock. */ - if (old && sport->lpuart_dma_rx_use) { - del_timer_sync(&sport->lpuart_timer); + if (old && sport->lpuart_dma_rx_use) lpuart_dma_rx_free(&sport->port); - } spin_lock_irqsave(&sport->port.lock, flags); @@ -2210,10 +2208,8 @@ lpuart32_set_termios(struct uart_port *port, struct ktermios *termios, * Since timer function acqures sport->port.lock, need to stop before * acquring same lock because otherwise del_timer_sync() can deadlock. */ - if (old && sport->lpuart_dma_rx_use) { - del_timer_sync(&sport->lpuart_timer); + if (old && sport->lpuart_dma_rx_use) lpuart_dma_rx_free(&sport->port); - } spin_lock_irqsave(&sport->port.lock, flags); @@ -3020,7 +3016,6 @@ static int lpuart_suspend(struct device *dev) * cannot resume as expected, hence gracefully release the * Rx DMA path before suspend and start Rx DMA path on resume. */ - del_timer_sync(&sport->lpuart_timer); lpuart_dma_rx_free(&sport->port); /* Disable Rx DMA to use UART port as wakeup source */ |