Guanghui Feng 77e9fed330 tty: tty_buffer: Fix the softlockup issue in flush_to_ldisc ... [ Upstream commit 3968ddcf05 ] When running ltp testcase(ltp/testcases/kernel/pty/pty04.c) with arm64, there is a soft lockup, which look like this one: Workqueue: events_unbound flush_to_ldisc Call trace: dump_backtrace+0x0/0x1ec show_stack+0x24/0x30 dump_stack+0xd0/0x128 panic+0x15c/0x374 watchdog_timer_fn+0x2b8/0x304 __run_hrtimer+0x88/0x2c0 __hrtimer_run_queues+0xa4/0x120 hrtimer_interrupt+0xfc/0x270 arch_timer_handler_phys+0x40/0x50 handle_percpu_devid_irq+0x94/0x220 __handle_domain_irq+0x88/0xf0 gic_handle_irq+0x84/0xfc el1_irq+0xc8/0x180 slip_unesc+0x80/0x214 [slip] tty_ldisc_receive_buf+0x64/0x80 tty_port_default_receive_buf+0x50/0x90 flush_to_ldisc+0xbc/0x110 process_one_work+0x1d4/0x4b0 worker_thread+0x180/0x430 kthread+0x11c/0x120 In the testcase pty04, The first process call the write syscall to send data to the pty master. At the same time, the workqueue will do the flush_to_ldisc to pop data in a loop until there is no more data left. When the sender and workqueue running in different core, the sender sends data fastly in full time which will result in workqueue doing work in loop for a long time and occuring softlockup in flush_to_ldisc with kernel configured without preempt. So I add need_resched check and cond_resched in the flush_to_ldisc loop to avoid it. Signed-off-by: Guanghui Feng <guanghuifeng@linux.alibaba.com> Link: https://lore.kernel.org/r/1633961304-24759-1-git-send-email-guanghuifeng@linux.alibaba.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>		2021-11-26 10:39:10 +01:00
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hvc	hvsi: don't panic on tty_register_driver failure	2021-09-18 13:40:22 +02:00
ipwireless
serdev
serial	serial: xilinx_uartps: Fix race condition causing stuck TX	2021-11-18 14:04:20 +01:00
vt	tty: Fix out-of-bound vmalloc access in imageblit	2021-10-06 15:55:45 +02:00
amiserial.c	tty: amiserial: fix TIOCSSERIAL permission check	2021-05-14 09:49:55 +02:00
cyclades.c
ehv_bytechan.c
goldfish.c
isicom.c
Kconfig
Makefile
mips_ejtag_fdc.c
moxa.c	tty: moxa: fix TIOCSSERIAL permission check	2021-05-14 09:49:56 +02:00
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
nozomi.c	tty: nozomi: Fix the error handling path of 'nozomi_card_init()'	2021-07-14 16:56:39 +02:00
pty.c
rocket_int.h
rocket.c
rocket.h
synclink_gt.c	tty: synclink_gt: rename a conflicting function name	2021-09-30 10:11:03 +02:00
synclink.c
synclinkmp.c
sysrq.c
tty_audit.c
tty_baudrate.c
tty_buffer.c	tty: tty_buffer: Fix the softlockup issue in flush_to_ldisc	2021-11-26 10:39:10 +01:00
tty_io.c	tty: Fix data race between tiocsti() and flush_to_ldisc()	2021-09-15 09:50:47 +02:00
tty_ioctl.c	tty: fix return value for unsupported termiox ioctls	2021-05-14 09:50:19 +02:00
tty_jobctrl.c
tty_ldisc.c
tty_ldsem.c
tty_mutex.c
tty_port.c
ttynull.c
vcc.c