Steven Rostedt fa7439531d ring-buffer: use commit counters for commit pointer accounting ... The ring buffer is made up of three sets of pointers. The head page pointer, which points to the next page for the reader to get. The commit pointer and commit index, which points to the page and index of the last committed write respectively. The tail pointer and tail index, which points to the page and the index of the last reserved data respectively (non committed). The commit pointer is only moved forward by the outer most writer. If a nested writer comes in, it will not move the pointer forward. The current implementation has a flaw. It assumes that the outer most writer successfully reserved data. There's a small race window where the outer most writer could find the tail pointer, but a nested writer could come in (via interrupt) and move the tail forward, and even the commit forward. The outer writer would not realized the commit moved forward and the accounting will break. This patch changes the design to use counters in the per cpu buffers to keep track of commits. The counters are incremented at the start of the commit, and decremented at the end. If the end commit counter is 1, then it moves the commit pointers. A loop is made to check for races between checking and moving the commit pointers. Only the outer commit should move the pointers anyway. The test of knowing if a reserve is equal to the last commit update is still needed to know for time keeping. The time code is much less racey than the commit updates. This change not only solves the mentioned race, but also makes the code simpler. [ Impact: fix commit race and simplify code ] Signed-off-by: Steven Rostedt <rostedt@goodmis.org>		2009-06-16 16:25:33 -04:00
..
irq	irq: slab alloc for default irq_affinity	2009-06-12 13:50:23 +03:00
power	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial	2009-06-14 13:46:25 -07:00
time	Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6	2009-06-11 09:01:14 +03:00
trace	ring-buffer: use commit counters for commit pointer accounting	2009-06-16 16:25:33 -04:00
.gitignore
acct.c	[CVE-2009-0029] System call wrappers part 04	2009-01-14 14:15:19 +01:00
async.c	async: Fix lack of boot-time console due to insufficient synchronization	2009-06-08 12:31:53 -07:00
audit_tree.c	Switch collect_mounts() to struct path	2009-06-11 21:36:01 -04:00
audit.c	Audit: remove spaces from audit_log_d_path	2009-04-05 13:49:04 -04:00
audit.h	fixing audit rule ordering mess, part 1	2009-01-04 15:14:41 -05:00
auditfilter.c	inotify: use GFP_NOFS in kernel_event() to work around a lockdep false-positive	2009-05-06 16:36:09 -07:00
auditsc.c	Audit: remove spaces from audit_log_d_path	2009-04-05 13:49:04 -04:00
backtracetest.c
bounds.c
capability.c	[CVE-2009-0029] System call wrappers part 04	2009-01-14 14:15:19 +01:00
cgroup_debug.c	debug cgroup: remove unneeded cgroup_lock	2009-04-02 19:04:54 -07:00
cgroup_freezer.c	freezer_cg: disable writing freezer.state of root cgroup	2008-11-12 17:17:16 -08:00
cgroup.c	Push BKL down into ->remount_fs()	2009-06-11 21:36:11 -04:00
compat.c	signals: implement sys_rt_tgsigqueueinfo	2009-04-30 19:24:24 +02:00
configs.c	kernel/configs.c: remove useless comments	2008-10-20 08:52:34 -07:00
cpu.c	cpumask: use set_cpu_active in init/main.c	2009-03-30 22:05:12 +10:30
cpuset.c	x86: remove some alloc_bootmem_cpumask_var calling	2009-06-11 19:27:07 +03:00
cred-internals.h	CRED: Inaugurate COW credentials	2008-11-14 10:39:23 +11:00
cred.c	CRED: Rename cred_exec_mutex to reflect that it's a guard against ptrace	2009-05-11 08:15:36 +10:00
delayacct.c	schedstat: consolidate per-task cpu runtime stats	2008-12-18 13:54:01 +01:00
dma-coherent.c	dma-coherent: Restore dma_alloc_from_coherent() large alloc fall back policy.	2009-01-21 18:51:53 +09:00
dma.c	kernel/dma.c: remove a CVS keyword	2008-10-16 11:21:30 -07:00
exec_domain.c	Get rid of indirect include of fs_struct.h	2009-03-31 23:00:27 -04:00
exit.c	Merge branch 'perfcounters-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip	2009-06-11 14:01:07 -07:00
extable.c	Merge branch 'tracing-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip	2009-04-05 11:04:19 -07:00
fork.c	Merge branch 'linus' into perfcounters/core	2009-06-11 17:55:42 +02:00
freezer.c	freezer_cg: use thaw_process() in unfreeze_cgroup()	2008-10-30 11:38:45 -07:00
futex_compat.c	CRED: Use RCU to access another task's creds and to release a task's own creds	2008-11-14 10:39:19 +11:00
futex.c	futex: fix restart in wait_requeue_pi	2009-05-20 10:34:32 +02:00
hrtimer.c	hrtimer: fix rq->lock inversion (again)	2009-03-31 14:52:52 +02:00
hung_task.c	softlockup: ensure the task has been switched out once	2009-02-11 11:04:16 +01:00
itimer.c	timers: split process wide cpu clocks/timers	2009-02-05 13:04:33 +01:00
kallsyms.c	kernel/kallsyms.c: replace deprecated __initcall with device_initcall and fix whitespace	2009-06-09 22:37:52 +02:00
Kconfig.freezer	container freezer: implement freezer cgroup subsystem	2008-10-20 08:52:34 -07:00
Kconfig.hz
Kconfig.preempt	rcu: provide RCU options on non-preempt architectures too	2008-12-25 09:31:28 +01:00
kexec.c	PM core: rename suspend and resume functions	2009-06-12 21:32:31 +02:00
kfifo.c
kgdb.c	sysrq, intel_fb: fix sysrq g collision	2009-05-15 07:56:24 -05:00
kmod.c	kmod: Release sub_info on cred allocation failure.	2009-05-26 12:11:19 -07:00
kprobes.c	kprobes: fix to use text_mutex around arm/disarm kprobe	2009-05-08 16:23:48 -07:00
ksysfs.c	kernel/ksysfs.c:fix dependence on CONFIG_NET	2009-01-06 10:44:31 -08:00
kthread.c	tracing/events: move trace point headers into include/trace/events	2009-04-14 22:05:43 -04:00
latencytop.c	sched, latencytop: incorporate review feedback from Andrew Morton	2009-02-11 10:18:04 +01:00
lockdep_internals.h	lockdep: increase MAX_LOCKDEP_ENTRIES and MAX_LOCKDEP_CHAINS	2009-05-12 19:59:52 +02:00
lockdep_proc.c	lockstat: warn about disabled lock debugging	2009-02-14 23:28:28 +01:00
lockdep_states.h	lockdep: move state bit definitions around	2009-02-14 23:27:59 +01:00
lockdep.c	Merge branch 'linus' into tracing/core	2009-05-07 11:17:34 +02:00
Makefile	Merge branch 'linus' into perfcounters/core	2009-06-11 17:55:42 +02:00
marker.c	markers/tracpoints: fix non-modular build	2008-11-16 09:52:03 +01:00
module.c	module: trim exception table on init free.	2009-06-12 21:47:04 +09:30
mutex-debug.c	mutex: implement adaptive spinning	2009-01-14 18:09:02 +01:00
mutex-debug.h	mutex: implement adaptive spinning	2009-01-14 18:09:02 +01:00
mutex.c	Merge branch 'linus' into perfcounters/core	2009-06-11 17:55:42 +02:00
mutex.h	mutex: implement adaptive spinning	2009-01-14 18:09:02 +01:00
notifier.c	Merge commit 'v2.6.28-rc6' into core/debug	2008-11-26 08:22:50 +01:00
ns_cgroup.c	cgroups: relax ns_can_attach checks to allow attaching to grandchild cgroups	2009-04-02 19:04:53 -07:00
nsproxy.c	User namespaces: set of cleanups (v2)	2008-11-24 18:57:41 -05:00
panic.c	Fix caller information for warn_slowpath_null	2009-05-16 13:41:28 -07:00
params.c	module_param: allow 'bool' module_params to be bool, not just int.	2009-06-12 21:46:58 +09:30
perf_counter.c	perf_counter: Add forward/backward attribute ABI compatibility	2009-06-12 14:28:52 +02:00
pid_namespace.c	signals: zap_pid_ns_process() should use force_sig()	2009-04-02 19:04:58 -07:00
pid.c	pids: refactor vnr/nr_ns helpers to make them safe	2009-04-02 19:05:02 -07:00
pm_qos_params.c
posix-cpu-timers.c	kernel/posix-cpu-timers.c: fix sparse warning	2009-04-30 08:08:31 +02:00
posix-timers.c	[CVE-2009-0029] System call wrappers part 05	2009-01-14 14:15:20 +01:00
printk.c	Merge branch 'printk-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip	2009-04-05 10:23:25 -07:00
profile.c	x86: remove some alloc_bootmem_cpumask_var calling	2009-06-11 19:27:07 +03:00
ptrace.c	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/security-testing-2.6	2009-06-11 10:01:41 -07:00
rcuclassic.c	kmemtrace, rcu: fix linux/rcutree.h and linux/rcuclassic.h dependencies	2009-04-03 12:23:02 +02:00
rcupdate.c	RCU: Don't try and predeclare inline funcs as it upsets some versions of gcc	2009-04-15 13:55:14 -07:00
rcupreempt_trace.c	"Tree RCU": scalable classic RCU implementation	2008-12-18 21:56:04 +01:00
rcupreempt.c	rcu: rcu_sched_grace_period(): kill the bogus flush_signals()	2009-05-05 20:28:05 +02:00
rcutorture.c	cpumask: convert rcutorture.c	2009-03-30 22:05:16 +10:30
rcutree_trace.c	rcu: Add __rcu_pending tracing to hierarchical RCU	2009-04-14 11:33:43 +02:00
rcutree.c	rcu: Add __rcu_pending tracing to hierarchical RCU	2009-04-14 11:33:43 +02:00
rcutree.h	kmemtrace, rcu: fix rcu_tree_trace.c data structure dependencies	2009-04-03 12:23:03 +02:00
relay.c	Merge branch 'tracing-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip	2009-04-05 11:04:19 -07:00
res_counter.c	memcg: memory cgroup resource counters for hierarchy	2009-01-08 08:31:05 -08:00
resource.c	Remove 'recurse into child resources' logic from 'reserve_region_with_split()'	2009-04-18 21:44:24 -07:00
rtmutex_common.h	rt_mutex: add proxy lock routines	2009-04-06 11:14:02 +02:00
rtmutex-debug.c
rtmutex-debug.h
rtmutex-tester.c
rtmutex.c	trivial: fix ETIMEOUT -> ETIMEDOUT typos	2009-06-12 18:01:50 +02:00
rtmutex.h
rwsem.c
sched_clock.c	sched: Fix fallback sched_clock()'s offset when using jiffies	2009-05-09 10:08:19 +02:00
sched_cpupri.c	sched: use slab in cpupri_init()	2009-06-11 19:27:12 +03:00
sched_cpupri.h	cpumask: remove cpumask_t from core	2009-03-30 22:05:17 +10:30
sched_debug.c	sched: remove unused fields from struct rq	2009-03-24 23:16:51 +01:00
sched_fair.c	sched: remove redundant hierarchy walk in check_preempt_wakeup	2009-04-09 08:19:08 +02:00
sched_features.h	Merge branch 'locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip	2009-03-30 17:17:35 -07:00
sched_idletask.c	sched, timers: move calc_load() to scheduler	2009-05-15 15:32:45 +02:00
sched_rt.c	cpumask: alloc zeroed cpumask for static cpumask_var_ts	2009-06-09 22:30:27 +09:30
sched_stats.h	sched: remove unused fields from struct rq	2009-03-24 23:16:51 +01:00
sched.c	sched: export kick_process	2009-06-12 22:27:01 +09:30
seccomp.c	x86-64: seccomp: fix 32/64 syscall hole	2009-03-02 15:41:30 -08:00
semaphore.c
signal.c	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/security-testing-2.6	2009-06-11 10:01:41 -07:00
slow-work.c	slow_work_thread() should do the exclusive wait	2009-06-11 11:26:38 -07:00
smp.c	cpumask: alloc zeroed cpumask for static cpumask_var_ts	2009-06-09 22:30:27 +09:30
softirq.c	Merge branch 'tracing-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip	2009-06-10 19:53:40 -07:00
softlockup.c	softlockup: decouple hung tasks check from softlockup detection	2009-01-16 14:06:04 +01:00
spinlock.c	Allow rwlocks to re-enable interrupts	2009-04-02 19:05:11 -07:00
srcu.c
stacktrace.c	stacktrace: provide save_stack_trace_tsk() weak alias	2008-12-25 11:44:43 +01:00
stop_machine.c	cpumask: remove cpumask_t from core	2009-03-30 22:05:17 +10:30
sys_ni.c	Merge commit 'v2.6.29-rc2' into perfcounters/core	2009-01-21 16:37:27 +01:00
sys.c	Merge branch 'linus' into perfcounters/core	2009-04-29 14:47:05 +02:00
sysctl_check.c	net: add ARP notify option for devices	2009-02-01 01:04:33 -08:00
sysctl.c	Merge branch 'perfcounters-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip	2009-06-11 14:01:07 -07:00
taskstats.c	cpumask: convert rest of files in kernel/	2009-01-01 10:12:28 +10:30
test_kprobes.c	kprobes: add tests for register_kprobes	2009-01-06 15:59:20 -08:00
time.c	[CVE-2009-0029] System call wrappers part 01	2009-01-14 14:15:18 +01:00
timeconst.pl
timer.c	Merge branch 'linus' into x86/mce3	2009-06-11 23:31:52 +02:00
tracepoint.c	tracepoints: dont update zero-sized tracepoint sections	2009-03-18 19:55:00 +01:00
tsacct.c	Fix fixpoint divide exception in acct_update_integrals	2009-03-09 08:13:35 -07:00
uid16.c	[CVE-2009-0029] System call wrappers part 19	2009-01-14 14:15:26 +01:00
up.c	smp_call_function_single(): be slightly less stupid, fix #2	2009-01-12 16:04:37 +01:00
user_namespace.c	Fix recursive lock in free_uid()/free_user_ns()	2009-02-27 16:26:21 -08:00
user.c	Merge branch 'master' into next	2009-03-24 10:52:46 +11:00
utsname_sysctl.c	proc_sysctl: use CONFIG_PROC_SYSCTL around ipc and utsname proc_handlers	2009-04-02 19:05:01 -07:00
utsname.c
wait.c	wait: don't use __wake_up_common()	2009-04-14 17:17:16 +02:00
workqueue.c	ftrace, workqueuetrace: make workqueue tracepoints use TRACE_EVENT macro	2009-06-02 01:10:40 +02:00