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Deadlock issue is seen when enabling CONFIG_PROVE_LOCKING=Y, and uart
console as wakeup source. Deadlock occurs when resuming from low power
mode if system is waked up via usart console.
The deadlock is triggered 100% when also disabling console suspend prior
to go to suspend.
Simplified call stack, deadlock condition:
- stm32_console_write <-- spin_lock already held
- print_circular_bug
- pm_wakeup_dev_event <-- triggers lockdep as seen above
- stm32_receive_chars
- stm32_interrupt <-- wakeup via uart console, takes the lock
So, revisit spin_lock in stm32-usart driver:
- there is no need to hold the lock to access ICR (atomic clear of status
flags)
- only hold the lock inside stm32_receive_chars() routine (no need to
call pm_wakeup_dev_event with lock held)
- keep stm32_transmit_chars() routine called with lock held
Fixes:
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.. | ||
hvc | ||
ipwireless | ||
serdev | ||
serial | ||
vt | ||
amiserial.c | ||
ehv_bytechan.c | ||
goldfish.c | ||
Kconfig | ||
Makefile | ||
mips_ejtag_fdc.c | ||
moxa.c | ||
moxa.h | ||
mxser.c | ||
mxser.h | ||
n_gsm.c | ||
n_hdlc.c | ||
n_null.c | ||
n_r3964.c | ||
n_tty.c | ||
nozomi.c | ||
pty.c | ||
synclink_gt.c | ||
sysrq.c | ||
tty_audit.c | ||
tty_baudrate.c | ||
tty_buffer.c | ||
tty_io.c | ||
tty_ioctl.c | ||
tty_jobctrl.c | ||
tty_ldisc.c | ||
tty_ldsem.c | ||
tty_mutex.c | ||
tty_port.c | ||
ttynull.c | ||
vcc.c |