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Steven Rostedt (Google) ca46e0ddcd ring-buffer: Fix wake ups when buffer_percent is set to 100 
commit 623b1f896fa8a669a277ee5a258307a16c7377a3 upstream.

The tracefs file "buffer_percent" is to allow user space to set a
water-mark on how much of the tracing ring buffer needs to be filled in
order to wake up a blocked reader.

 0 - is to wait until any data is in the buffer
 1 - is to wait for 1% of the sub buffers to be filled
 50 - would be half of the sub buffers are filled with data
 100 - is not to wake the waiter until the ring buffer is completely full

Unfortunately the test for being full was:

	dirty = ring_buffer_nr_dirty_pages(buffer, cpu);
	return (dirty * 100) > (full * nr_pages);

Where "full" is the value for "buffer_percent".

There is two issues with the above when full == 100.

1. dirty * 100 > 100 * nr_pages will never be true
   That is, the above is basically saying that if the user sets
   buffer_percent to 100, more pages need to be dirty than exist in the
   ring buffer!

2. The page that the writer is on is never considered dirty, as dirty
   pages are only those that are full. When the writer goes to a new
   sub-buffer, it clears the contents of that sub-buffer.

That is, even if the check was ">=" it would still not be equal as the
most pages that can be considered "dirty" is nr_pages - 1.

To fix this, add one to dirty and use ">=" in the compare.

Link: https://lore.kernel.org/linux-trace-kernel/20231226125902.4a057f1d@gandalf.local.home

Cc: stable@vger.kernel.org
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Fixes: 03329f9939781 ("tracing: Add tracefs file buffer_percentage")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-11-18 12:12:03 +01:00
..
bpf bpf: Fix precision tracking for BPF_ALU | BPF_TO_BE | BPF_END 2024-11-18 11:43:21 +01:00
cgroup cgroup: Remove duplicates in cgroup v1 tasks file 2024-11-08 11:25:51 +01:00
configs Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
debug kgdb: Flush console before entering kgdb on panic 2024-11-18 11:43:15 +01:00
dma Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
entry Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
events perf: Fix perf_event_validate_size() lockdep splat 2024-11-18 12:11:57 +01:00
futex futex: Don't include process MM in futex key on no-MMU 2024-11-18 11:42:47 +01:00
gcov Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
irq genirq/generic_chip: Make irq_remove_generic_chip() irqdomain aware 2024-11-18 11:43:25 +01:00
kcsan Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
livepatch livepatch: Fix missing newline character in klp_resolve_symbols() 2024-11-18 11:43:05 +01:00
locking lockdep: Fix block chain corruption 2024-11-18 12:10:56 +01:00
power PM: hibernate: Clean up sync_read handling in snapshot_write_next() 2024-11-18 11:43:24 +01:00
printk printk: Don't allow userspace to write to /dev/kmsg 2024-11-17 17:43:00 +01:00
rcu rcu: kmemleak: Ignore kmemleak false positives when RCU-freeing objects 2024-11-18 11:43:24 +01:00
sched Revert "kernel: ems/ego: Allow CPU frequency changes to be amended before they're set" 2024-11-18 07:48:15 +01:00
time Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
trace ring-buffer: Fix wake ups when buffer_percent is set to 100 2024-11-18 12:12:03 +01:00
acct.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
async.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
audit.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
audit.h Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
audit_fsnotify.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
audit_tree.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
audit_watch.c audit: don't WARN_ON_ONCE(!current->mm) in audit_exe_compare() 2024-11-18 11:43:21 +01:00
auditfilter.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
auditsc.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
backtracetest.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
bounds.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
capability.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
cfi.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
compat.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
configs.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
context_tracking.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
cpu.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
cpu_pm.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
crash_core.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
crash_dump.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
cred.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
delayacct.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
dma.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
exec_domain.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
exit.c security: samsung: defex_lsm: nuke 2024-06-15 16:20:49 -03:00
extable.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
fail_function.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
fork.c security: samsung: defex_lsm: nuke 2024-06-15 16:20:49 -03:00
freezer.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
gen_kheaders.sh Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
groups.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
hung_task.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
iomem.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
irq_work.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
jump_label.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
kallsyms.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
kcmp.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
Kconfig.freezer Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
Kconfig.hz Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
Kconfig.locks Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
Kconfig.preempt Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
kcov.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
kexec.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
kexec_core.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
kexec_elf.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
kexec_file.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
kexec_internal.h Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
kheaders.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
kmod.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
kprobes.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
ksysfs.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
kthread.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
latencytop.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
Makefile kernel: Use the stock defconfig for /proc/config.gz 2024-06-15 16:20:14 -03:00
module-internal.h Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
module.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
module_signature.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
module_signing.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
notifier.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
nsproxy.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
padata.c crypto: pcrypt - Fix hungtask for PADATA_RESET 2024-11-18 11:43:13 +01:00
panic.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
params.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
pid.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
pid_namespace.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
profile.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
ptrace.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
range.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
reboot.c kernel/reboot: emergency_restart: Set correct system_state 2024-11-18 11:43:25 +01:00
regset.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
relay.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
resource.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
rseq.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
scftorture.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
scs.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
seccomp.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
signal.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
smp.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
smpboot.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
smpboot.h Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
softirq.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
stackleak.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
stacktrace.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
static_call.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
stop_machine.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
sys.c f2fs: Add support for reporting a fake kernel version to fsck 2024-11-17 17:43:26 +01:00
sys_ni.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
sysctl-test.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
sysctl.c drivers: usb: add toggle for disabling newly added USB devices 2024-10-04 20:09:29 -03:00
task_work.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
taskstats.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
test_kprobes.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
torture.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
tracepoint.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
tsacct.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
ucount.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
uid16.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
uid16.h Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
umh.c security: samsung: defex_lsm: nuke 2024-06-15 16:20:49 -03:00
up.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
user-return-notifier.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
user.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
user_namespace.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
usermode_driver.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
utsname.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
utsname_sysctl.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
watch_queue.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
watchdog.c watchdog: move softlockup_panic back to early_param 2024-11-18 11:43:21 +01:00
watchdog_hld.c Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00
workqueue.c Revert "workqueue: remove unused cancel_work()" 2024-11-18 12:11:11 +01:00
workqueue_internal.h Import A536BXXU9EXDC 2024-06-15 16:02:09 -03:00