Sergey Senozhatsky f74fc96e32 tty/serial: do not free trasnmit buffer page under port lock ... [ Upstream commit d72402145a ] LKP has hit yet another circular locking dependency between uart console drivers and debugobjects [1]: CPU0 CPU1 rhltable_init() __init_work() debug_object_init uart_shutdown() /* db->lock */ /* uart_port->lock */ debug_print_object() free_page() printk() call_console_drivers() debug_check_no_obj_freed() /* uart_port->lock */ /* db->lock */ debug_print_object() So there are two dependency chains: uart_port->lock -> db->lock And db->lock -> uart_port->lock This particular circular locking dependency can be addressed in several ways: a) One way would be to move debug_print_object() out of db->lock scope and, thus, break the db->lock -> uart_port->lock chain. b) Another one would be to free() transmit buffer page out of db->lock in UART code; which is what this patch does. It makes sense to apply a) and b) independently: there are too many things going on behind free(), none of which depend on uart_port->lock. The patch fixes transmit buffer page free() in uart_shutdown() and, additionally, in uart_port_startup() (as was suggested by Dmitry Safonov). [1] https://lore.kernel.org/lkml/20181211091154.GL23332@shao2-debian/T/#u Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Jiri Slaby <jslaby@suse.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Waiman Long <longman@redhat.com> Cc: Dmitry Safonov <dima@arista.com> Cc: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>		2019-01-26 09:32:40 +01:00
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hvc	tty: hvc: hvc_write() fix break condition	2018-09-10 18:04:31 +02:00
ipwireless
serdev
serial	tty/serial: do not free trasnmit buffer page under port lock	2019-01-26 09:32:40 +01:00
vt	vt: fix broken display when running aptitude	2018-11-13 11:09:00 -08:00
amiserial.c
cyclades.c
ehv_bytechan.c
goldfish.c
isicom.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_tracerouter.c
n_tracesink.c
n_tracesink.h
n_tty.c	tty: wipe buffer if not echoing data	2018-12-01 09:37:34 +01:00
nozomi.c
pty.c
rocket_int.h
rocket.c
rocket.h
synclink_gt.c
synclink.c
synclinkmp.c
sysrq.c
tty_audit.c
tty_baudrate.c	termios, tty/tty_baudrate.c: fix buffer overrun	2018-11-21 09:19:20 +01:00
tty_buffer.c	tty: wipe buffer.	2018-12-01 09:37:34 +01:00
tty_io.c	tty: Don't hold ldisc lock in tty_reopen() if ldisc present	2019-01-22 21:40:28 +01:00
tty_ioctl.c
tty_jobctrl.c
tty_ldisc.c
tty_ldsem.c	tty/ldsem: Wake up readers after timed out down_write()	2019-01-22 21:40:28 +01:00
tty_mutex.c
tty_port.c	tty: do not set TTY_IO_ERROR flag if console port	2018-12-13 09:16:22 +01:00
vcc.c