[PATCH v2] serial: omap: Fix error handling in probe

From: Semen Protsenko
Date: Thu Apr 30 2015 - 11:36:43 EST

There is pm_qos_add_request() being executed on serial_omap_probe(),
which stores "&up->pm_qos_request" from omap-serial driver to
"pm_qos_array[PM_QOS_CPU_DMA_LATENCY]->constraints". If
serial_omap_probe() fails after pm_qos_add_request() (e.g. on
uart_add_one_port() call), pm_qos_array still keeping pm_qos_request
struct from omap-serial driver, which is not valid anymore (since driver
failed). This leads further to kernel crash on pm_qos_update_target(),
executing from some completely different driver.

We were observing this while trying to run audio playback while having
one of omap-serial driver instances failed on uart_add_one_port() call:
Unable to handle kernel paging request at virtual address fffffffc
(plist_add) from (pm_qos_update_target)
(pm_qos_update_target) from (pm_qos_add_request)
(pm_qos_add_request) from (snd_pcm_hw_params)
(snd_pcm_hw_params) from (snd_pcm_common_ioctl1)
(snd_pcm_common_ioctl1) from (snd_pcm_playback_ioctl1)
(snd_pcm_playback_ioctl1) from (snd_pcm_playback_ioctl)
(snd_pcm_playback_ioctl) from (do_vfs_ioctl)
(do_vfs_ioctl) from (SyS_ioctl)
(SyS_ioctl) from (ret_fast_syscall)

This patch adds pm_qos_remove_request() on fail path in
serial_omap_probe() in order to fix this issue. While at it, free the
wakeup settings on fail path as well, just like it's done in

Signed-off-by: Semen Protsenko <semen.protsenko@xxxxxxxxxxxxxxx>
drivers/tty/serial/omap-serial.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c
index 211479a..7f49172 100644
--- a/drivers/tty/serial/omap-serial.c
+++ b/drivers/tty/serial/omap-serial.c
@@ -1735,6 +1735,8 @@ static int serial_omap_probe(struct platform_device *pdev)
+ pm_qos_remove_request(&up->pm_qos_request);
+ device_init_wakeup(up->dev, false);
return ret;

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