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Peter Zijlstra 06dc92142b tty/ldsem, locking/rwsem: Add missing ACQUIRE to read_failed sleep loop 
[ Upstream commit 952041a863 ]

While reviewing rwsem down_slowpath, Will noticed ldsem had a copy of
a bug we just found for rwsem.

  X = 0;

  CPU0			CPU1

  rwsem_down_read()
    for (;;) {
      set_current_state(TASK_UNINTERRUPTIBLE);

                        X = 1;
                        rwsem_up_write();
                          rwsem_mark_wake()
                            atomic_long_add(adjustment, &sem->count);
                            smp_store_release(&waiter->task, NULL);

      if (!waiter.task)
        break;

      ...
    }

  r = X;

Allows 'r == 0'.

Reported-by: Will Deacon <will@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Will Deacon <will@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 4898e640ca ("tty: Add timed, writer-prioritized rw semaphore")
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2019-08-16 10:12:50 +02:00
..
hvc tty: Don't force RISCV SBI console as preferred console 2019-05-22 07:37:43 +02:00
ipwireless tty: ipwireless: fix missing checks for ioremap 2019-05-31 06:46:30 -07:00
serdev
serial serial: sh-sci: Fix TX DMA buffer flushing and workqueue races 2019-07-31 07:27:04 +02:00
vt vt/fbcon: deinitialize resources in visual_init() after failed memory allocation 2019-06-09 09:17:21 +02:00
amiserial.c
cyclades.c
ehv_bytechan.c
goldfish.c
isicom.c
Kconfig tty: ldisc: add sysctl to prevent autoloading of ldiscs 2019-04-17 08:38:47 +02:00
Makefile
mips_ejtag_fdc.c
moxa.c
moxa.h
mxser.c
mxser.h
n_gsm.c
n_hdlc.c tty/n_hdlc: fix __might_sleep warning 2019-01-31 08:14:36 +01:00
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.c tty: rocket: fix incorrect forward declaration of 'rp_init()' 2019-07-10 09:53:44 +02:00
rocket.h
rocket_int.h
synclink.c
synclink_gt.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: increase the default flip buffer limit to 2*640K 2019-04-05 22:33:13 +02:00
tty_io.c tty: ldisc: add sysctl to prevent autoloading of ldiscs 2019-04-17 08:38:47 +02:00
tty_ioctl.c
tty_jobctrl.c
tty_ldisc.c tty: ldisc: add sysctl to prevent autoloading of ldiscs 2019-04-17 08:38:47 +02:00
tty_ldsem.c tty/ldsem, locking/rwsem: Add missing ACQUIRE to read_failed sleep loop 2019-08-16 10:12:50 +02:00
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