Steven Rostedt (VMware) a2a67e53f9 ring-buffer: Have ring_buffer_iter_empty() return true when empty ... commit 78f7a45dac2a2d2002f98a3a95f7979867868d73 upstream. I noticed that reading the snapshot file when it is empty no longer gives a status. It suppose to show the status of the snapshot buffer as well as how to allocate and use it. For example: ># cat snapshot # tracer: nop # # # * Snapshot is allocated * # # Snapshot commands: # echo 0 > snapshot : Clears and frees snapshot buffer # echo 1 > snapshot : Allocates snapshot buffer, if not already allocated. # Takes a snapshot of the main buffer. # echo 2 > snapshot : Clears snapshot buffer (but does not allocate or free) # (Doesn't have to be '2' works with any number that # is not a '0' or '1') But instead it just showed an empty buffer: ># cat snapshot # tracer: nop # # entries-in-buffer/entries-written: 0/0 #P:4 # # _-----=> irqs-off # / _----=> need-resched # | / _---=> hardirq/softirq # || / _--=> preempt-depth # ||| / delay # TASK-PID CPU# |||| TIMESTAMP FUNCTION # | | | |||| | | What happened was that it was using the ring_buffer_iter_empty() function to see if it was empty, and if it was, it showed the status. But that function was returning false when it was empty. The reason was that the iter header page was on the reader page, and the reader page was empty, but so was the buffer itself. The check only tested to see if the iter was on the commit page, but the commit page was no longer pointing to the reader page, but as all pages were empty, the buffer is also. Fixes: 651e22f270 ("ring-buffer: Always reset iterator to reader page") Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2017-04-27 09:09:31 +02:00
..
bpf	bpf, inode: disallow userns mounts	2016-06-24 10:18:17 -07:00
configs	kconfig: tinyconfig: provide whole choice blocks to avoid warnings	2016-09-24 10:07:42 +02:00
debug	kernel/debug/debug_core.c: more properly delay for secondary CPUs	2017-01-06 11:16:16 +01:00
events	perf/core: Fix event inheritance on fork()	2017-03-26 12:13:18 +02:00
gcov	gcov: add support for GCC 5.1	2015-06-30 19:44:57 -07:00
irq	genirq/generic_chip: Add irq_unmap callback	2016-10-31 04:13:59 -06:00
livepatch	livepatch: x86: fix relocation computation with kASLR	2015-11-11 17:36:04 +01:00
locking	locking/rtmutex: Use READ_ONCE() in rt_mutex_owner()	2016-12-15 08:49:22 -08:00
power	PM / sleep: fix device reference leak in test_suspend	2016-11-26 09:54:53 +01:00
printk	printk: use rcuidle console tracepoint	2017-02-23 17:43:10 +01:00
rcu	rcu: Fix soft lockup for rcu_nocb_kthread	2016-12-08 07:15:24 +01:00
sched	sched/rt: Add a missing rescheduling point	2017-03-31 09:49:54 +02:00
time	tick/broadcast: Prevent NULL pointer dereference	2017-01-12 11:22:51 +01:00
trace	ring-buffer: Have ring_buffer_iter_empty() return true when empty	2017-04-27 09:09:31 +02:00
.gitignore	certs: add .gitignore to stop git nagging about x509_certificate_list	2015-10-21 15:18:35 +01:00
acct.c
async.c
audit.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
audit.h	audit: audit_tree_match can be boolean	2015-11-04 08:23:51 -05:00
audit_fsnotify.c	audit: clean simple fsnotify implementation	2015-08-06 16:14:53 -04:00
audit_tree.c	audit: audit_tree_match can be boolean	2015-11-04 08:23:51 -05:00
audit_watch.c	audit: fix exe_file access in audit_exe_compare	2016-09-24 10:07:36 +02:00
auditfilter.c	audit: fix comment block whitespace	2015-11-04 08:23:51 -05:00
auditsc.c	audit: fix a double fetch in audit_log_single_execve_arg()	2016-08-20 18:09:22 +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	compat: cleanup coding in compat_get_bitmap() and compat_put_bitmap()	2015-06-04 23:57:18 +02:00
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	kernel/cpu_pm: fix cpu_cluster_pm_exit comment	2015-09-03 02:42:20 +02:00
cpuset.c	cpuset: handle race between CPU hotplug and cpuset_hotplug_work	2016-10-07 15:23:40 +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	wait/ptrace: assume __WALL if the child is traced	2016-06-07 18:14:35 -07:00
extable.c	kernel/extable.c: remove duplicated include	2015-09-10 13:29:01 -07:00
fork.c	kernek/fork.c: allocate idle task for a CPU always on its local node	2017-03-26 12:13:18 +02:00
freezer.c
futex.c	futex: Add missing error handling to FUTEX_REQUEUE_PI	2017-03-22 12:04:19 +01:00
futex_compat.c	ptrace: use fsuid, fsgid, effective creds for fs access checks	2016-02-25 12:01:16 -08:00
groups.c	kernel: conditionally support non-root users, groups and capabilities	2015-04-15 16:35:22 -07:00
hung_task.c	kernel/hung_task.c: change hung_task.c to use for_each_process_thread()	2015-04-15 16:35:22 -07:00
irq_work.c	treewide: Remove old email address	2015-11-23 09:44:58 +01:00
jump_label.c	jump_labels: API for flushing deferred jump label updates	2017-01-19 20:17:19 +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	locking/qrwlock: Rename QUEUE_RWLOCK to QUEUED_RWLOCKS	2015-05-12 09:46:00 +02:00
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	kexec: split kexec_file syscall code to kexec_file.c	2015-09-10 13:29:01 -07:00
kmod.c	kmod: don't run async usermode helper as a child of kworker thread	2015-10-23 17:55:10 +09:00
kprobes.c	perf/x86/hw_breakpoints: Disallow kernel breakpoints unless kprobe-safe	2015-08-04 10:16:54 +02:00
ksysfs.c	kexec: split kexec_load syscall from kexec core code	2015-09-10 13:29:01 -07:00
kthread.c	cgroup, kthread: close race window where new kthreads can be migrated to non-root cgroups	2017-04-21 09:30:04 +02:00
latencytop.c
Makefile	sys_membarrier(): system-wide memory barrier (generic, x86)	2015-09-11 15:21:34 -07:00
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: Invalidate signatures on force-loaded modules	2016-08-20 18:09:27 +02:00
module_signing.c	KEYS: Merge the type-specific data with the payload data	2015-10-21 15:18:36 +01:00
notifier.c	Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2015-09-01 08:40:25 -07:00
nsproxy.c
padata.c	padata: avoid race in reordering	2017-04-08 09:53:32 +02:00
panic.c	printk: do cond_resched() between lines while outputting to consoles	2016-02-17 12:30:57 -08:00
params.c	Nothing exciting, minor tweaks and cleanups.	2015-11-09 15:53:39 -08:00
pid.c	pidns: fix NULL dereference in __task_pid_nr_ns()	2015-11-24 12:03:55 -08:00
pid_namespace.c
profile.c	mm: rename alloc_pages_exact_node() to __alloc_pages_node()	2015-09-08 15:35:28 -07:00
ptrace.c	ptrace: fix PTRACE_LISTEN race corrupting task->state	2017-04-12 12:38:33 +02:00
range.c
reboot.c	kexec: split kexec_load syscall from kexec core code	2015-09-10 13:29:01 -07:00
relay.c	kernel/relay.c: use kvfree() in relay_free_page_array()	2015-06-30 19:44:59 -07:00
resource.c	kernel/resource.c: fix muxed resource handling in __request_region()	2016-03-03 15:07:29 -08:00
seccomp.c	seccomp: always propagate NO_NEW_PRIVS on tsync	2016-03-03 15:07:25 -08:00
signal.c	kernel/signal.c: unexport sigsuspend()	2015-11-20 16:17:32 -08:00
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	stop_machine: Kill smp_hotplug_thread->pre_unpark, introduce stop_machine_unpark()	2015-10-20 10:23:55 +02:00
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	prctl: take mmap sem for writing to protect against others	2016-02-25 12:01:25 -08:00
sys_ni.c	mm: mlock: add new mlock system call	2015-11-05 19:34:48 -08:00
sysctl.c	sysctl: fix proc_doulongvec_ms_jiffies_minmax()	2017-02-01 08:30:52 +01:00
sysctl_binary.c	fs/coredump: prevent fsuid=0 dumps into user-controlled directories	2016-04-12 09:08:58 -07:00
task_work.c	task_work: remove fifo ordering guarantee	2015-09-05 13:46:58 -07:00
taskstats.c
test_kprobes.c
torture.c	torture: Consolidate cond_resched_rcu_qs() into stutter_wait()	2015-10-06 11:25:01 -07:00
tracepoint.c	tracepoint: Give priority to probes of tracepoints	2015-10-25 21:33:54 -04:00
tsacct.c
uid16.c
up.c
user-return-notifier.c
user.c
user_namespace.c	capabilities: ambient capabilities	2015-09-04 16:54:41 -07:00
utsname.c
utsname_sysctl.c
watchdog.c	kernel/watchdog: use nmi registers snapshot in hardlockup handler	2017-01-06 11:16:16 +01:00
workqueue.c	workqueue: fix rebind bound workers warning	2016-05-18 17:06:50 -07:00
workqueue_internal.h