Steven Rostedt (Red Hat) 78a3db11cb ring-buffer: Fix infinite spin in reading buffer ... commit 24607f114fd14f2f37e3e0cb3d47bce96e81e848 upstream. Commit 651e22f2701b "ring-buffer: Always reset iterator to reader page" fixed one bug but in the process caused another one. The reset is to update the header page, but that fix also changed the way the cached reads were updated. The cache reads are used to test if an iterator needs to be updated or not. A ring buffer iterator, when created, disables writes to the ring buffer but does not stop other readers or consuming reads from happening. Although all readers are synchronized via a lock, they are only synchronized when in the ring buffer functions. Those functions may be called by any number of readers. The iterator continues down when its not interrupted by a consuming reader. If a consuming read occurs, the iterator starts from the beginning of the buffer. The way the iterator sees that a consuming read has happened since its last read is by checking the reader "cache". The cache holds the last counts of the read and the reader page itself. Commit 651e22f2701b changed what was saved by the cache_read when the rb_iter_reset() occurred, making the iterator never match the cache. Then if the iterator calls rb_iter_reset(), it will go into an infinite loop by checking if the cache doesn't match, doing the reset and retrying, just to see that the cache still doesn't match! Which should never happen as the reset is suppose to set the cache to the current value and there's locks that keep a consuming reader from having access to the data. Fixes: 651e22f2701b "ring-buffer: Always reset iterator to reader page" Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2014-10-09 12:18:42 -07:00
..
cpu	sched, idle: Fix the idle polling state logic	2013-11-29 11:11:42 -08:00
debug	kgdb/sysrq: fix inconstistent help message of sysrq key	2013-04-30 17:04:10 -07:00
events	perf: fix perf bug in fork()	2014-10-09 12:18:42 -07:00
gcov
irq	genirq: Sanitize spurious interrupt detection of threaded irqs	2014-06-30 20:09:45 -07:00
power	PM / sleep: Use valid_state() for platform-dependent sleep states only	2014-10-05 14:54:15 -07:00
sched	printk: rename printk_sched to printk_deferred	2014-08-07 14:30:26 -07:00
time	alarmtimer: Lock k_itimer during timer callback	2014-10-05 14:54:14 -07:00
trace	ring-buffer: Fix infinite spin in reading buffer	2014-10-09 12:18:42 -07:00
.gitignore	kernel/hz.bc: ignore.	2013-04-22 07:09:06 -07:00
acct.c	fs: Fix hang with BSD accounting on frozen filesystem	2013-05-04 14:57:58 -04:00
async.c	async: rename and redefine async_func_ptr	2013-03-12 13:59:14 -07:00
audit.c	CAPABILITIES: remove undefined caps from all processes	2014-09-17 09:03:57 -07:00
audit.h	audit: fix mq_open and mq_unlink to add the MQ root as a hidden parent audit_names record	2013-12-04 10:57:03 -08:00
audit_tree.c	kernel/audit_tree.c:audit_add_tree_rule(): protect `rule' from kill_rules()	2013-06-12 16:29:46 -07:00
audit_watch.c
auditfilter.c	auditfilter.c: fix kernel-doc warnings	2013-05-24 16:22:52 -07:00
auditsc.c	auditsc: audit_krule mask accesses need bounds checking	2014-06-16 13:42:53 -07:00
backtracetest.c
bounds.c
capability.c	CAPABILITIES: remove undefined caps from all processes	2014-09-17 09:03:57 -07:00
cgroup.c	cgroup: use a dedicated workqueue for cgroup destruction	2013-12-04 10:57:20 -08:00
cgroup_freezer.c
compat.c	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal	2013-05-01 07:21:43 -07:00
configs.c	proc: Supply PDE attribute setting accessor functions	2013-05-01 17:29:18 -04:00
context_tracking.c	Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2013-06-20 08:18:35 -10:00
cpu.c	sched: Fix hotplug vs. set_cpus_allowed_ptr()	2014-06-11 12:03:24 -07:00
cpu_pm.c
cpuset.c	cpuset,mempolicy: fix sleeping function called from invalid context	2014-07-17 15:58:00 -07:00
crash_dump.c
cred.c
delayacct.c
dma.c
elfcore.c
exec_domain.c
exit.c	introduce for_each_thread() to replace the buggy while_each_thread()	2014-10-05 14:54:15 -07:00
extable.c	extable: Flip the sorting message	2013-04-15 13:25:16 +02:00
fork.c	perf: fix perf bug in fork()	2014-10-09 12:18:42 -07:00
freezer.c	libata, freezer: avoid block device removal while system is frozen	2014-01-09 12:24:23 -08:00
futex.c	futex: Make lookup_pi_state more robust	2014-06-07 13:25:41 -07:00
futex_compat.c
groups.c
hrtimer.c	hrtimer: Set expiry time before switch_hrtimer_base()	2014-06-07 13:25:31 -07:00
hung_task.c
irq_work.c
itimer.c
jump_label.c
kallsyms.c	kernel: kallsyms: memory override issue, need check destination buffer length	2013-04-15 15:17:26 +09:30
kcmp.c	kcmp: fix standard comparison bug	2014-10-05 14:54:13 -07:00
Kconfig.freezer
Kconfig.hz
Kconfig.locks	locking/mutex: Disable optimistic spinning on some architectures	2014-07-28 08:00:07 -07:00
Kconfig.preempt
kexec.c	PCI: Disable Bus Master only on kexec reboot	2013-12-20 07:45:08 -08:00
kmod.c	usermodehelper: check subprocess_info->path != NULL	2013-05-16 12:01:11 -07:00
kprobes.c	kprobes: Fix to free gone and unused optprobes	2013-05-28 10:37:59 +02:00
ksysfs.c
kthread.c	kthread: implement probe_kthread_data()	2013-04-30 17:04:02 -07:00
latencytop.c
lglock.c
lockdep.c	Merge branch 'for-3.10/drivers' of git://git.kernel.dk/linux-block	2013-05-08 11:51:05 -07:00
lockdep_internals.h
lockdep_proc.c
lockdep_states.h
Makefile	We get rid of the general module prefix confusion with a binary config option,	2013-05-05 10:58:06 -07:00
modsign_certificate.S	CONFIG_SYMBOL_PREFIX: cleanup.	2013-03-15 15:09:43 +10:30
modsign_pubkey.c
module-internal.h
module.c	ftrace/module: Hardcode ftrace_module_init() call into load_module()	2014-06-07 13:25:28 -07:00
module_signing.c
mutex-debug.c
mutex-debug.h
mutex.c	mutex: Back out architecture specific check for negative mutex count	2013-04-19 09:33:36 +02:00
mutex.h
notifier.c
nsproxy.c	proc: Split the namespace stuff out into linux/proc_ns.h	2013-05-01 17:29:39 -04:00
padata.c
panic.c	dump_stack: implement arch-specific hardware description in task dumps	2013-04-30 17:04:02 -07:00
params.c	params: Fix potential memory leak in add_sysfs_param()	2013-03-18 11:40:21 +00:00
pid.c	pidns: Fix hang in zap_pid_ns_processes by sending a potentially extra wakeup	2013-09-26 17:18:27 -07:00
pid_namespace.c	pid_namespace: pidns_get() should check task_active_pid_ns() != NULL	2014-04-26 17:15:34 -07:00
posix-cpu-timers.c	posix_timers: Fix pre-condition to stop the tick on full dynticks	2013-04-22 19:59:25 +02:00
posix-timers.c	posix-timers: Remove unused variable	2013-04-18 12:51:19 +02:00
printk.c	printk: rename printk_sched to printk_deferred	2014-08-07 14:30:26 -07:00
profile.c	proc: Supply PDE attribute setting accessor functions	2013-05-01 17:29:18 -04:00
ptrace.c	exec/ptrace: fix get_dumpable() incorrect tests	2013-11-29 11:11:44 -08:00
range.c	range: Do not add new blank slot with add_range_with_merge	2013-06-18 11:32:10 -05:00
rcu.h
rcupdate.c
rcutiny.c
rcutiny_plugin.h
rcutorture.c
rcutree.c	rcu: Fix deadlock with CPU hotplug, RCU GP init, and timer migration	2013-06-10 13:37:12 -07:00
rcutree.h	rcu: Don't call wakeup() with rcu_node structure ->lock held	2013-06-10 13:37:11 -07:00
rcutree_plugin.h	rcu: Don't allocate bootmem from rcu_init()	2013-05-15 10:41:12 -07:00
rcutree_trace.c	rcutrace: single_open() leaks	2013-05-05 00:16:35 -04:00
relay.c	Merge branch 'for-3.10/core' of git://git.kernel.dk/linux-block	2013-05-08 10:13:35 -07:00
res_counter.c
resource.c	mem hotunplug: fix kfree() of bootmem memory	2013-04-29 15:54:40 -07:00
rtmutex-debug.c
rtmutex-debug.h	rtmutex: Handle deadlock detection smarter	2014-07-17 15:58:04 -07:00
rtmutex-tester.c	locking/rtmutex/tester: Set correct permissions on sysfs files	2013-04-10 14:48:37 +02:00
rtmutex.c	rtmutex: Plug slow unlock race	2014-07-17 15:58:04 -07:00
rtmutex.h	rtmutex: Handle deadlock detection smarter	2014-07-17 15:58:04 -07:00
rtmutex_common.h
rwsem.c	Revert "rw_semaphore: remove up/down_read_non_owner"	2013-03-23 15:53:52 -07:00
seccomp.c	seccomp: allow BPF_XOR based ALU instructions.	2013-03-26 11:07:19 +11:00
semaphore.c	semaphore: use `bool' type for semaphore_waiter's up	2013-04-30 17:04:08 -07:00
signal.c	Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next	2013-05-01 14:08:52 -07:00
smp.c	kernel/smp.c:on_each_cpu_cond(): fix warning in fallback path	2014-09-17 09:03:57 -07:00
smpboot.c	kthread: Prevent unpark race which puts threads on the wrong cpu	2013-04-12 14:18:43 +02:00
smpboot.h
softirq.c	irq: Force hardirq exit's softirq processing on its own stack	2013-10-13 16:08:34 -07:00
spinlock.c
srcu.c
stacktrace.c
stop_machine.c
sys.c	reboot: rigrate shutdown/reboot to boot cpu	2013-06-12 16:29:44 -07:00
sys_ni.c	unify compat fanotify_mark(2), switch to COMPAT_SYSCALL_DEFINE	2013-05-09 13:46:38 -04:00
sysctl.c	perf: Enforce 1 as lower limit for perf_event_max_sample_rate	2014-06-11 12:03:27 -07:00
sysctl_binary.c	switch compat_sys_sysctl to COMPAT_SYSCALL_DEFINE	2013-05-09 14:53:20 -04:00
task_work.c
taskstats.c
test_kprobes.c	kernel/: rename random32() to prandom_u32()	2013-04-29 18:28:42 -07:00
time.c	timekeeping: Use inject_offset in warp_clock	2013-03-15 16:50:20 -07:00
timeconst.bc
timer.c	timer: Prevent overflow in apply_slack	2014-06-07 13:25:30 -07:00
tracepoint.c	tracepoint: Do not waste memory on mods with no tracepoints	2014-05-30 21:52:11 -07:00
tsacct.c
uid16.c
up.c
user-return-notifier.c
user.c	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2013-05-01 17:51:54 -07:00
user_namespace.c	user namespace: fix incorrect memory barriers	2014-04-26 17:15:34 -07:00
utsname.c	proc: Split the namespace stuff out into linux/proc_ns.h	2013-05-01 17:29:39 -04:00
utsname_sysctl.c
wait.c
watchdog.c	watchdog: Add comments to explain the watchdog_disabled variable	2013-03-14 08:24:05 +01:00
workqueue.c	workqueue: zero cpumask of wq_numa_possible_cpumask on init	2014-07-17 15:58:00 -07:00
workqueue_internal.h	workqueue: include workqueue info when printing debug dump of a worker task	2013-04-30 17:04:02 -07:00