Steven Rostedt
a5fb833172
ring-buffer: Fix uninitialized read_stamp ...
The ring buffer reader page is used to swap a page from the writable
ring buffer. If the writer happens to be on that page, it ends up on the
reader page, but will simply move off of it, back into the writable ring
buffer as writes are added.
The time stamp passed back to the readers is stored in the cpu_buffer per
CPU descriptor. This stamp is updated when a swap of the reader page takes
place, and it reads the current stamp from the page taken from the writable
ring buffer. Everytime a writer goes to a new page, it updates the time stamp
of that page.
The problem happens if a reader reads a page from an empty per CPU ring buffer.
If the buffer is empty, the swap still takes place, placing the writer at the
start of the reader page. If at a later time, a write happens, it updates the
page's time stamp and continues. But the problem is that the read_stamp does
not get updated, because the page was already swapped.
The solution to this was to not swap the page if the ring buffer happens to
be empty. This also removes the side effect that the writes on the reader
page will not get updated because the writer never gets back on the reader
page without a swap. That is, if a read happens on an empty buffer, but then
no reads happen for a while. If a swap took place, and the writer were to start
writing a lot of data (function tracer), it will start overflowing the ring buffer
and overwrite the older data. But because the writer never goes back onto the
reader page, the data left on the reader page never gets overwritten. This
causes the reader to see really old data, followed by a jump to newer data.
Link: http://lkml.kernel.org/r/1340060577-9112-1-git-send-email-dhsharp@google.com
Google-Bug-Id: 6410455
Reported-by: David Sharp <dhsharp@google.com>
tested-by: David Sharp <dhsharp@google.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2012-06-28 13:52:15 -04:00
KGDB/KDB regression fixes
2012-04-04 17:26:08 -07:00
perf: Introduce perf_pmu_migrate_context()
2012-06-18 12:13:21 +02:00
gcov: disable CONSTRUCTORS for UML
2011-07-26 16:49:45 -07:00
Merge branches 'irq-urgent-for-linus' and 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2012-06-04 11:36:51 -07:00
PM / Hibernate: Use get_gendisk to verify partition if resume_file is integer format
2012-05-18 20:44:59 +02:00
Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2012-06-08 14:59:29 -07:00
Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2012-06-08 09:11:33 -07:00
ring-buffer: Fix uninitialized read_stamp
2012-06-28 13:52:15 -04:00
Merge branch 'for-linus2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
2012-01-08 12:19:57 -08:00
kernel/async: remove redundant declaration.
2012-01-13 09:32:18 +10:30
constify path argument of audit_log_d_path()
2012-03-20 21:29:40 -04:00
audit: remove AUDIT_SETUP_CONTEXT as it isn't used
2012-01-17 16:16:57 -05:00
audit_tree,rcu: Convert call_rcu(__put_tree) to kfree_rcu()
2011-07-20 14:10:11 -07:00
audit: allow interfield comparison in audit rules
2012-01-17 16:17:01 -05:00
seccomp: remove duplicated failure logging
2012-04-14 11:13:20 +10:00
userns: Teach inode_capable to understand inodes whose uids map to other namespaces.
2012-05-15 14:59:24 -07:00
Merge branch 'for-3.5-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
2012-06-05 11:54:12 -07:00
cgroup: convert all non-memcg controllers to the new cftype interface
2012-04-01 12:09:55 -07:00
new helper: sigsuspend()
2012-05-21 23:52:30 -04:00
kernel/configs.c: include MODULE_*() when CONFIG_IKCONFIG_PROC=n
2011-07-25 20:57:15 -07:00
kernel/cpu.c: document clear_tasks_mm_cpumask()
2012-05-31 17:49:30 -07:00
kernel/cpu_pm.c: fix various typos
2012-05-31 17:49:27 -07:00
Merge branch 'for-3.5' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
2012-05-22 17:40:19 -07:00
Merge branch 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux
2011-11-06 19:44:47 -08:00
keys: kill task_struct->replacement_session_keyring
2012-05-23 22:11:41 -04:00
KVM: Steal time implementation
2011-07-14 12:59:14 +03:00
Remove all #inclusions of asm/system.h
2012-03-28 18:30:03 +01:00
Revert "mm: correctly synchronize rss-counters at exit/exec"
2012-06-07 17:54:07 -07:00
extable: Skip sorting if sorted at build time.
2012-04-19 15:06:55 -07:00
Revert "mm: correctly synchronize rss-counters at exit/exec"
2012-06-07 17:54:07 -07:00
PM / Freezer: Remove references to TIF_FREEZE in comments
2012-03-04 23:08:54 +01:00
futex: Mark get_robust_list as deprecated
2012-03-29 11:37:17 +02:00
futex: Mark get_robust_list as deprecated
2012-03-29 11:37:17 +02:00
userns: Convert in_group_p and in_egroup_p to use kgid_t
2012-05-03 03:29:33 -07:00
Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2011-11-28 08:43:52 -08:00
hung task debugging: Inject NMI when hung and going to panic
2012-04-25 12:39:25 +02:00
irq_work: fix compile failure on tile from missing include
2012-04-13 13:15:16 -04:00
itimer: Use printk_once instead of WARN_ONCE
2012-04-10 11:00:30 +02:00
static keys: Inline the static_key_enabled() function
2012-02-28 20:01:08 +01:00
vsprintf: fix %ps on non symbols when using kallsyms
2012-05-29 16:22:32 -07:00
syscalls, x86: add __NR_kcmp syscall
2012-05-31 17:49:32 -07:00
locking/kconfig: Simplify INLINE_SPIN_UNLOCK usage
2012-03-23 13:18:57 +01:00
locking/kconfig: Simplify INLINE_SPIN_UNLOCK usage
2012-03-23 13:18:57 +01:00
Merge branch 'akpm' (Andrew's patch-bomb)
2012-03-28 17:19:28 -07:00
[media] kernel:kfifo: export __kfifo_max_r symbol
2012-04-11 18:24:37 -03:00
kmod.c: fix kernel-doc warning
2012-05-31 17:49:28 -07:00
kprobes: return proper error code from register_kprobe()
2012-03-05 15:49:42 -08:00
kernel: ksysfs.c is implicitly using stat.h
2011-10-31 09:20:13 -04:00
freezer: kill unused set_freezable_with_signal()
2011-11-23 09:28:17 -08:00
kernel: Map most files to use export.h instead of module.h
2011-10-31 09:20:12 -04:00
brlocks/lglocks: turn into functions
2012-05-29 23:28:41 -04:00
lockdep: Add CPU-idle/offline warning to lockdep-RCU splat
2012-02-21 09:06:06 -08:00
kernel: Map most files to use export.h instead of module.h
2011-10-31 09:20:12 -04:00
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
2012-06-01 10:34:35 -07:00
Guard check in module loader against integer overflow
2012-05-23 22:28:53 +09:30
kernel: Map most files to use export.h instead of module.h
2011-10-31 09:20:12 -04:00
sched/rt: Use schedule_preempt_disabled()
2012-03-01 10:28:03 +01:00
kernel: Map most files to use export.h instead of module.h
2011-10-31 09:20:12 -04:00
kernel: Map most files to use export.h instead of module.h
2011-10-31 09:20:12 -04:00
padata: Fix cpu hotplug
2012-03-29 19:52:46 +08:00
panic: fix stack dump print on direct call to panic()
2012-04-12 13:12:12 -07:00
params: replace printk(KERN_<LVL>...) with pr_<lvl>(...)
2012-05-04 17:28:18 -07:00
mm: add a low limit to alloc_large_system_hash
2012-05-24 00:28:21 -04:00
sysctl: make kernel.ns_last_pid control dependent on CHECKPOINT_RESTORE
2012-05-31 17:49:32 -07:00
[S390] cputime: add sparse checking and cleanup
2011-12-15 14:56:19 +01:00
kernel: Map most files to use export.h instead of module.h
2011-10-31 09:20:12 -04:00
printk() - isolate KERN_CONT users from ordinary complete lines
2012-05-14 12:36:45 -07:00
kernel: Map most files to use export.h instead of module.h
2011-10-31 09:20:12 -04:00
userns: Convert ptrace, kill, set_priority permission checks to work with kuids and kgids
2012-05-03 03:28:51 -07:00
range: fix bogus misuse of module.h to get printk()
2011-10-31 09:20:11 -04:00
rcu: Allow nesting of rcu_idle_enter() and rcu_idle_exit()
2012-02-21 09:06:12 -08:00
rcu: Make exit_rcu() more precise and consolidate
2012-05-02 14:48:27 -07:00
rcu: Add RCU_NONIDLE() for idle-loop RCU read-side critical sections
2012-02-21 09:06:13 -08:00
rcu: Make exit_rcu() more precise and consolidate
2012-05-02 14:48:27 -07:00
rcu: Add rcutorture test for call_srcu()
2012-04-30 10:48:26 -07:00
Merge branch 'rcu/next' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/rcu
2012-05-14 08:41:46 +02:00
Merge branches 'barrier.2012.05.09a', 'fixes.2012.04.26a', 'inline.2012.05.02b' and 'srcu.2012.05.07b' into HEAD
2012-05-11 10:14:21 -07:00
Merge branches 'barrier.2012.05.09a', 'fixes.2012.04.26a', 'inline.2012.05.02b' and 'srcu.2012.05.07b' into HEAD
2012-05-11 10:14:21 -07:00
rcu: Make rcu_barrier() less disruptive
2012-05-09 14:27:54 -07:00
relay: prevent integer overflow in relay_open()
2012-02-10 09:04:49 +01:00
rescounters: add res_counter_uncharge_until()
2012-05-29 16:22:27 -07:00
kernel/resource.c: correct the comment of allocate_resource()
2012-05-31 17:49:26 -07:00
lockdep, rtmutex, bug: Show taint flags on error
2011-12-06 08:16:49 +01:00
rtmutex-tester: convert sysdev_class to a regular subsystem
2011-12-14 14:54:22 -08:00
Revert "rcu: Permit rt_mutex_unlock() with irqs disabled"
2011-12-11 10:33:18 -08:00
Remove all #inclusions of asm/system.h
2012-03-28 18:30:03 +01:00
seccomp: fix build warnings when there is no CONFIG_SECCOMP_FILTER
2012-04-18 12:24:52 +10:00
semaphore: fix improper comment reference to mutex
2012-04-05 17:15:55 -07:00
new helper: signal_delivered()
2012-06-01 12:58:52 -04:00
smp: Implement kick_all_cpus_sync()
2012-05-08 12:35:06 +02:00
smpboot, idle: Fix comment mismatch over idle_threads_init()
2012-05-24 22:58:08 +02:00
smp: Fix idle_thread_init() inline stub
2012-05-04 12:52:25 +02:00
Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2012-03-20 10:32:09 -07:00
locking/kconfig: Simplify INLINE_SPIN_UNLOCK usage
2012-03-23 13:18:57 +01:00
rcu: Implement per-domain single-threaded call_srcu() state machine
2012-04-30 10:48:25 -07:00
kernel: Map most files to use export.h instead of module.h
2011-10-31 09:20:12 -04:00
Merge branch 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux
2011-11-06 19:44:47 -08:00
c/r: prctl: drop VMA flags test on PR_SET_MM_ stack data assignment
2012-06-07 14:43:55 -07:00
syscalls, x86: add __NR_kcmp syscall
2012-05-31 17:49:32 -07:00
sysctl: fix write access to dmesg_restrict/kptr_restrict
2012-04-05 14:51:43 +10:00
binary_sysctl(): fix memory leak
2011-12-20 10:25:04 -08:00
task_work_add: generic process-context callbacks
2012-05-23 22:09:21 -04:00
Make TASKSTATS require root access
2011-09-19 17:04:37 -07:00
time: Remove bogus comments
2012-03-15 18:17:55 -07:00
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
2012-05-23 17:42:39 -07:00
static keys: Introduce 'struct static_key', static_key_true()/false() and static_key_slow_[inc|dec]()
2012-02-24 10:05:59 +01:00
[S390] cputime: add sparse checking and cleanup
2011-12-15 14:56:19 +01:00
userns: Convert setting and getting uid and gid system calls to use kuid and kgid
2012-05-03 03:28:41 -07:00
kernel: Map most files to use export.h instead of module.h
2011-10-31 09:20:12 -04:00
kernel: Map most files to use export.h instead of module.h
2011-10-31 09:20:12 -04:00
userns: Silence silly gcc warning.
2012-05-19 15:44:40 -06:00
userns: Store uid and gid values in struct cred with kuid_t and kgid_t types
2012-05-03 03:28:38 -07:00
userns: Use cred->user_ns instead of cred->user->user_ns
2012-04-07 16:55:51 -07:00
Merge branch 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux
2011-11-06 19:44:47 -08:00
lockdep/waitqueues: Add better annotation
2011-12-21 10:07:39 +01:00
watchdog: Quiet down the boot messages
2012-06-14 12:20:50 +02:00
lockdep: fix oops in processing workqueue
2012-05-15 08:08:31 -07:00
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