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android_kernel_oneplus_msm8998/kernel
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Prateek Sood 70cc08c44f locking/rwsem-xadd: Fix missed wakeup due to reordering of load 
commit 9c29c31830a4eca724e137a9339137204bbb31be upstream.

If a spinner is present, there is a chance that the load of
rwsem_has_spinner() in rwsem_wake() can be reordered with
respect to decrement of rwsem count in __up_write() leading
to wakeup being missed:

 spinning writer                  up_write caller
 ---------------                  -----------------------
 [S] osq_unlock()                 [L] osq
  spin_lock(wait_lock)
  sem->count=0xFFFFFFFF00000001
            +0xFFFFFFFF00000000
  count=sem->count
  MB
                                   sem->count=0xFFFFFFFE00000001
                                             -0xFFFFFFFF00000001
                                   spin_trylock(wait_lock)
                                   return
 rwsem_try_write_lock(count)
 spin_unlock(wait_lock)
 schedule()

Reordering of atomic_long_sub_return_release() in __up_write()
and rwsem_has_spinner() in rwsem_wake() can cause missing of
wakeup in up_write() context. In spinning writer, sem->count
and local variable count is 0XFFFFFFFE00000001. It would result
in rwsem_try_write_lock() failing to acquire rwsem and spinning
writer going to sleep in rwsem_down_write_failed().

The smp_rmb() will make sure that the spinner state is
consulted after sem->count is updated in up_write context.

Signed-off-by: Prateek Sood <prsood@codeaurora.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dave@stgolabs.net
Cc: longman@redhat.com
Cc: parri.andrea@gmail.com
Cc: sramana@codeaurora.org
Link: http://lkml.kernel.org/r/1504794658-15397-1-git-send-email-prsood@codeaurora.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-09-19 22:48:56 +02:00
..
bpf bpf: fix references to free_bpf_prog_info() in comments 2018-08-06 16:24:37 +02:00
configs kconfig: tinyconfig: provide whole choice blocks to avoid warnings 2016-09-24 10:07:42 +02:00
debug kdb: make "mdr" command repeat 2018-05-30 07:49:17 +02:00
events perf/core: Fix perf_output_read_group() 2018-05-30 07:49:12 +02:00
gcov gcov: disable for COMPILE_TEST 2018-01-23 19:50:10 +01:00
irq genirq: Delay incrementing interrupt count if it's disabled/pending 2018-09-15 09:40:40 +02:00
livepatch livepatch: x86: fix relocation computation with kASLR 2015-11-11 17:36:04 +01:00
locking locking/rwsem-xadd: Fix missed wakeup due to reordering of load 2018-09-19 22:48:56 +02:00
power PM / sleep: wakeup: Fix build error caused by missing SRCU support 2018-09-09 20:04:34 +02:00
printk braille-console: Fix value returned by _braille_console_setup 2018-03-22 09:23:23 +01:00
rcu rcu: Allow for page faults in NMI handlers 2017-10-18 09:20:41 +02:00
sched sched/rt: Fix rq->clock_update_flags < RQCF_ACT_SKIP warning 2018-05-30 07:49:08 +02:00
time nohz: Fix local_timer_softirq_pending() 2018-08-09 12:19:27 +02:00
trace uprobes: Use synchronize_rcu() not synchronize_sched() 2018-09-09 20:04:34 +02:00
.gitignore
acct.c kernel/acct.c: fix the acct->needcheck check in check_free_space() 2018-01-10 09:27:08 +01:00
async.c kernel/async.c: revert "async: simplify lowest_in_progress()" 2018-02-16 20:09:45 +01:00
audit.c audit: return on memory error to avoid null pointer dereference 2018-05-30 07:49:16 +02:00
audit.h
audit_fsnotify.c
audit_tree.c
audit_watch.c audit: Fix use after free in audit_remove_watch_rule() 2017-08-24 17:02:35 -07:00
auditfilter.c audit: allow not equal op for audit by executable 2018-08-06 16:24:38 +02:00
auditsc.c audit: allow not equal op for audit by executable 2018-08-06 16:24:38 +02:00
backtracetest.c
bounds.c
capability.c exec: Ensure mm->user_ns contains the execed files 2017-01-06 11:16:14 +01:00
cgroup.c cgroup, kthread: close race window where new kthreads can be migrated to non-root cgroups 2017-04-21 09:30:04 +02:00
cgroup_freezer.c cgroup: fix handling of multi-destination migration from subtree_control enabling 2015-12-03 10:18:21 -05:00
cgroup_pids.c cgroup_pids: don't account for the root cgroup 2015-12-03 10:18:21 -05:00
compat.c
configs.c
context_tracking.c context_tracking: avoid irq_save/irq_restore on guest entry and exit 2015-11-10 12:06:23 +01:00
cpu.c stable-fixup: hotplug: fix unused function warning 2017-01-12 11:22:48 +01:00
cpu_pm.c
cpuset.c sched/cpuset/pm: Fix cpuset vs. suspend-resume bugs 2017-10-12 11:27:35 +02:00
crash_dump.c
cred.c cred: Reject inodes with invalid ids in set_create_file_as() 2016-09-15 08:27:49 +02:00
delayacct.c
dma.c
elfcore.c
exec_domain.c
exit.c kernel/exit.c: avoid undefined behaviour when calling wait4() 2018-05-26 08:48:51 +02:00
extable.c kernel/extable.c: mark core_kernel_text notrace 2017-07-21 07:44:56 +02:00
fork.c kthread: Fix use-after-free if kthread fork fails 2018-09-19 22:48:55 +02:00
freezer.c
futex.c futex: futex_wake_op, fix sign_extend32 sign bits 2018-05-26 08:48:51 +02:00
futex_compat.c ptrace: use fsuid, fsgid, effective creds for fs access checks 2016-02-25 12:01:16 -08:00
groups.c kernel: make groups_sort calling a responsibility group_info allocators 2018-01-10 09:27:10 +01:00
hung_task.c
irq_work.c treewide: Remove old email address 2015-11-23 09:44:58 +01:00
jump_label.c jump_label: Invoke jump_label_test() via early_initcall() 2017-12-16 10:33:55 +01:00
kallsyms.c
kcmp.c ptrace: use fsuid, fsgid, effective creds for fs access checks 2016-02-25 12:01:16 -08:00
Kconfig.freezer
Kconfig.hz
Kconfig.locks
Kconfig.preempt
kexec.c kexec: use file name as the output message prefix 2015-11-06 17:50:42 -08:00
kexec_core.c kexec: use file name as the output message prefix 2015-11-06 17:50:42 -08:00
kexec_file.c kexec: fix double-free when failing to relocate the purgatory 2016-09-24 10:07:36 +02:00
kexec_internal.h
kmod.c
kprobes.c kprobes: Make list and blacklist root user read only 2018-09-05 09:18:40 +02:00
ksysfs.c
kthread.c kthread, tracing: Don't expose half-written comm when creating kthreads 2018-09-09 20:04:34 +02:00
latencytop.c
Makefile
membarrier.c Fix: Disable sys_membarrier when nohz_full is enabled 2017-03-12 06:37:26 +01:00
memremap.c mm: fix devm_memremap_pages crash, use mem_hotplug_{begin, done} 2017-01-19 20:17:18 +01:00
module-internal.h
module.c module/retpoline: Warn about missing retpoline in module 2018-02-25 11:03:52 +01:00
module_signing.c
notifier.c
nsproxy.c
padata.c padata: free correct variable 2017-05-20 14:27:02 +02:00
panic.c kernel/panic.c: add missing \n 2017-07-05 14:37:19 +02:00
params.c Nothing exciting, minor tweaks and cleanups. 2015-11-09 15:53:39 -08:00
pid.c pidns: disable pid allocation if pid_ns_prepare_proc() is failed in alloc_pid() 2018-04-13 19:50:03 +02:00
pid_namespace.c pid_ns: Sleep in TASK_INTERRUPTIBLE in zap_pid_ns_processes 2017-05-25 14:30:11 +02:00
profile.c profile: hide unused functions when !CONFIG_PROC_FS 2018-02-25 11:03:44 +01:00
ptrace.c ptrace: Properly initialize ptracer_cred on fork 2017-06-14 13:16:20 +02:00
range.c
reboot.c
relay.c kernel/relay.c: limit kmalloc size to KMALLOC_MAX_SIZE 2018-05-30 07:49:00 +02:00
resource.c resource: fix integer overflow at reallocation 2018-04-24 09:32:05 +02:00
seccomp.c seccomp: Move speculation migitation control to arch code 2018-07-25 10:18:27 +02:00
signal.c kernel/signal.c: avoid undefined behaviour in kill_something_info 2018-05-30 07:48:52 +02:00
smp.c mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd 2015-11-06 17:50:42 -08:00
smpboot.c
smpboot.h
softirq.c
stacktrace.c
stop_machine.c kernel: remove stop_machine() Kconfig dependency 2015-12-12 10:15:34 -08:00
sys.c sys: don't hold uts_sem while accessing userspace memory 2018-09-09 20:04:35 +02:00
sys_ni.c mm: mlock: add new mlock system call 2015-11-05 19:34:48 -08:00
sysctl.c sched/sysctl: Check user input value of sysctl_sched_time_avg 2018-09-05 09:18:33 +02:00
sysctl_binary.c fs/coredump: prevent fsuid=0 dumps into user-controlled directories 2016-04-12 09:08:58 -07:00
task_work.c
taskstats.c
test_kprobes.c
torture.c
tracepoint.c tracepoint: Do not warn on ENOMEM 2018-05-16 10:06:47 +02:00
tsacct.c
uid16.c kernel: make groups_sort calling a responsibility group_info allocators 2018-01-10 09:27:10 +01:00
up.c
user-return-notifier.c
user.c
user_namespace.c userns: move user access out of the mutex 2018-09-09 20:04:35 +02:00
utsname.c
utsname_sysctl.c sys: don't hold uts_sem while accessing userspace memory 2018-09-09 20:04:35 +02:00
watchdog.c kernel/watchdog: use nmi registers snapshot in hardlockup handler 2017-01-06 11:16:16 +01:00
workqueue.c workqueue: use put_device() instead of kfree() 2018-05-30 07:49:04 +02:00
workqueue_internal.h workqueue: Fix NULL pointer dereference 2017-11-15 17:13:11 +01:00