github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-05-18 20:03:14 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity
623b1f896f
linux/kernel
History
Steven Rostedt (Google) 623b1f896f ring-buffer: Fix wake ups when buffer_percent is set to 100 
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: 03329f9939 ("tracing: Add tracefs file buffer_percentage")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2023-12-29 09:18:30 -05:00
..
bpf bpf: Do not allocate percpu memory at init stage 2023-11-15 07:51:06 -08:00
cgroup sched: psi: fix unprivileged polling against cgroups 2023-11-14 22:27:00 +01:00
configs hardening: Provide Kconfig fragments for basic options 2023-09-22 09:50:55 -07:00
debug kdb: Corrects comment for kdballocenv 2023-11-06 17:13:55 +00:00
dma swiotlb: fix out-of-bounds TLB allocations with CONFIG_SWIOTLB_DYNAMIC 2023-11-08 16:27:05 +01:00
entry entry: Remove empty addr_limit_user_check() 2023-08-23 10:32:39 +02:00
events perf/core: Fix cpuctx refcounting 2023-11-15 04:18:31 +01:00
futex futex: Fix hardcoded flags 2023-11-15 04:02:25 +01:00
gcov gcov: annotate struct gcov_iterator with __counted_by 2023-10-18 14:43:22 -07:00
irq As usual, lots of singleton and doubleton patches all over the tree and 2023-11-02 20:53:31 -10:00
kcsan mm: delete checks for xor_unlock_is_negative_byte() 2023-10-18 14:34:17 -07:00
livepatch livepatch: Fix missing newline character in klp_resolve_symbols() 2023-09-20 11:24:18 +02:00
locking RCU pull request for v6.7 2023-10-30 18:01:41 -10:00
module This update includes the following changes: 2023-11-02 16:15:30 -10:00
power Power management updates for 6.7-rc1 2023-10-31 15:38:12 -10:00
printk TTY/Serial changes for 6.7-rc1 2023-11-03 15:44:25 -10:00
rcu RCU fixes for v6.7 2023-11-08 09:47:52 -08:00
sched sched/fair: Fix the decision for load balance 2023-11-14 22:27:01 +01:00
time - Do the push of pending hrtimers away from a CPU which is being 2023-11-19 13:35:07 -08:00
trace ring-buffer: Fix wake ups when buffer_percent is set to 100 2023-12-29 09:18:30 -05:00
.gitignore
acct.c fs: rename __mnt_{want,drop}_write*() helpers 2023-09-11 15:05:50 +02:00
async.c
audit_fsnotify.c
audit_tree.c As usual, lots of singleton and doubleton patches all over the tree and 2023-11-02 20:53:31 -10:00
audit_watch.c audit: don't WARN_ON_ONCE(!current->mm) in audit_exe_compare() 2023-11-14 17:34:27 -05:00
audit.c audit: move trailing statements to next line 2023-08-15 18:16:14 -04:00
audit.h audit: correct audit_filter_inodes() definition 2023-07-21 12:17:25 -04:00
auditfilter.c audit: move trailing statements to next line 2023-08-15 18:16:14 -04:00
auditsc.c audit,io_uring: io_uring openat triggers audit reference count underflow 2023-10-13 18:34:46 +02:00
backtracetest.c
bounds.c
capability.c lsm: constify the 'target' parameter in security_capget() 2023-08-08 16:48:47 -04:00
cfi.c
compat.c sched_getaffinity: don't assume 'cpumask_size()' is fully initialized 2023-03-14 19:32:38 -07:00
configs.c
context_tracking.c locking/atomic: treewide: use raw_atomic*_<op>() 2023-06-05 09:57:20 +02:00
cpu_pm.c cpuidle, cpu_pm: Remove RCU fiddling from cpu_pm_{enter,exit}() 2023-01-13 11:48:15 +01:00
cpu.c - Do the push of pending hrtimers away from a CPU which is being 2023-11-19 13:35:07 -08:00
crash_core.c crash_core.c: remove unneeded functions 2023-10-04 10:41:58 -07:00
crash_dump.c
cred.c lsm/stable-6.7 PR 20231030 2023-10-30 20:13:17 -10:00
delayacct.c delayacct: track delays from IRQ/SOFTIRQ 2023-04-18 16:39:34 -07:00
dma.c
exec_domain.c
exit.c As usual, lots of singleton and doubleton patches all over the tree and 2023-11-02 20:53:31 -10:00
exit.h exit: add internal include file with helpers 2023-09-21 12:03:50 -06:00
extable.c
fail_function.c kernel/fail_function: fix memory leak with using debugfs_lookup() 2023-02-08 13:36:22 +01:00
fork.c As usual, lots of singleton and doubleton patches all over the tree and 2023-11-02 20:53:31 -10:00
freezer.c freezer,sched: Use saved_state to reduce some spurious wakeups 2023-09-18 08:14:36 +02:00
gen_kheaders.sh Revert "kheaders: substituting --sort in archive creation" 2023-05-28 16:20:21 +09:00
groups.c groups: Convert group_info.usage to refcount_t 2023-09-29 11:28:39 -07:00
hung_task.c kernel/hung_task.c: set some hung_task.c variables storage-class-specifier to static 2023-04-08 13:45:37 -07:00
iomem.c kernel/iomem.c: remove __weak ioremap_cache helper 2023-08-21 13:37:28 -07:00
irq_work.c trace: Add trace_ipi_send_cpu() 2023-03-24 11:01:29 +01:00
jump_label.c jump_label: Prevent key->enabled int overflow 2022-12-01 15:53:05 -08:00
kallsyms_internal.h
kallsyms_selftest.c Modules changes for v6.6-rc1 2023-08-29 17:32:32 -07:00
kallsyms_selftest.h
kallsyms.c kallsyms: Change func signature for cleanup_symbol_name() 2023-08-25 15:00:36 -07:00
kcmp.c file: convert to SLAB_TYPESAFE_BY_RCU 2023-10-19 11:02:48 +02:00
Kconfig.freezer
Kconfig.hz
Kconfig.kexec docs: fix link s390/zfcpdump.rst 2023-10-04 10:41:56 -07:00
Kconfig.locks
Kconfig.preempt
kcov.c kcov: add prototypes for helper functions 2023-06-09 17:44:17 -07:00
kexec_core.c crash_core: move crashk_*res definition into crash_core.c 2023-10-04 10:41:58 -07:00
kexec_elf.c
kexec_file.c integrity-v6.6 2023-08-30 09:16:56 -07:00
kexec_internal.h
kexec.c kernel: kexec: copy user-array safely 2023-10-09 16:59:47 +10:00
kheaders.c kheaders: Use array declaration instead of char 2023-03-24 20:10:59 -07:00
kprobes.c kprobes: kretprobe scalability improvement 2023-10-18 23:59:54 +09:00
ksyms_common.c kallsyms: make kallsyms_show_value() as generic function 2023-06-08 12:27:20 -07:00
ksysfs.c crash: hotplug support for kexec_load() 2023-08-24 16:25:14 -07:00
kthread.c As usual, lots of singleton and doubleton patches all over the tree and 2023-11-02 20:53:31 -10:00
latencytop.c
Makefile v6.5-rc1-modules-next 2023-06-28 15:51:08 -07:00
module_signature.c
notifier.c notifiers: add tracepoints to the notifiers infrastructure 2023-04-08 13:45:38 -07:00
nsproxy.c nsproxy: Convert nsproxy.count to refcount_t 2023-08-21 11:29:12 -07:00
padata.c padata: Fix refcnt handling in padata_free_shell() 2023-10-27 18:04:24 +08:00
panic.c panic: use atomic_try_cmpxchg in panic() and nmi_panic() 2023-10-04 10:41:56 -07:00
params.c kernel: params: Remove unnecessary ‘0’ values from err 2023-07-10 12:47:01 -07:00
pid_namespace.c pid: pid_ns_ctl_handler: remove useless comment 2023-10-04 10:41:57 -07:00
pid_sysctl.h memfd: replace ratcheting feature from vm.memfd_noexec with hierarchy 2023-08-21 13:37:59 -07:00
pid.c pidfd: prevent a kernel-doc warning 2023-09-19 13:21:33 -07:00
profile.c
ptrace.c mm: make __access_remote_vm() static 2023-10-18 14:34:15 -07:00
range.c
reboot.c kernel/reboot: Add device to sys_off_handler 2023-07-28 11:33:09 +01:00
regset.c
relay.c kernel: relay: remove unnecessary NULL values from relay_open_buf 2023-08-18 10:18:55 -07:00
resource_kunit.c
resource.c resource: Unify next_resource() and next_resource_skip_children() 2023-10-05 13:58:07 +02:00
rseq.c rseq: Extend struct rseq with per-memory-map concurrency ID 2022-12-27 12:52:12 +01:00
scftorture.c scftorture: Pause testing after memory-allocation failure 2023-07-14 15:02:57 -07:00
scs.c
seccomp.c seccomp: Add missing kerndoc notations 2023-08-17 12:32:15 -07:00
signal.c As usual, lots of singleton and doubleton patches all over the tree and 2023-11-02 20:53:31 -10:00
smp.c CSD lock commits for v6.7 2023-10-30 17:56:53 -10:00
smpboot.c kthread: add kthread_stop_put 2023-10-04 10:41:57 -07:00
smpboot.h
softirq.c sched/core: introduce sched_core_idle_cpu() 2023-07-13 15:21:50 +02:00
stackleak.c stackleak: allow to specify arch specific stackleak poison function 2023-04-20 11:36:35 +02:00
stacktrace.c stacktrace: Export stack_trace_save_tsk 2023-09-11 23:59:47 -04:00
static_call_inline.c
static_call.c
stop_machine.c
sys_ni.c asm-generic updates for v6.7 2023-11-01 15:28:33 -10:00
sys.c prctl: Disable prctl(PR_SET_MDWE) on parisc 2023-11-18 19:35:31 +01:00
sysctl-test.c
sysctl.c asm-generic updates for v6.7 2023-11-01 15:28:33 -10:00
task_work.c task_work: add kerneldoc annotation for 'data' argument 2023-09-19 13:21:32 -07:00
taskstats.c taskstats: fill_stats_for_tgid: use for_each_thread() 2023-10-04 10:41:57 -07:00
torture.c torture: Print out torture module parameters 2023-09-24 17:24:01 +02:00
tracepoint.c tracepoint: Allow livepatch module add trace event 2023-02-18 14:34:36 -05:00
tsacct.c
ucount.c sysctl: Add size to register_sysctl 2023-08-15 15:26:17 -07:00
uid16.c
uid16.h
umh.c sysctl: fix unused proc_cap_handler() function warning 2023-06-29 15:19:43 -07:00
up.c smp: Change function signatures to use call_single_data_t 2023-09-13 14:59:24 +02:00
user_namespace.c As usual, lots of singleton and doubleton patches all over the tree and 2023-11-02 20:53:31 -10:00
user-return-notifier.c
user.c binfmt_misc: enable sandboxed mounts 2023-10-11 08:46:01 -07:00
usermode_driver.c
utsname_sysctl.c utsname: simplify one-level sysctl registration for uts_kern_table 2023-04-13 11:49:35 -07:00
utsname.c
vhost_task.c vhost: Fix worker hangs due to missed wake up calls 2023-06-08 15:43:09 -04:00
watch_queue.c kernel: watch_queue: copy user-array safely 2023-10-09 16:59:48 +10:00
watchdog_buddy.c watchdog/hardlockup: move SMP barriers from common code to buddy code 2023-06-19 16:25:28 -07:00
watchdog_perf.c watchdog/perf: add a weak function for an arch to detect if perf can use NMIs 2023-06-09 17:44:21 -07:00
watchdog.c watchdog: move softlockup_panic back to early_param 2023-11-01 12:10:02 -07:00
workqueue_internal.h workqueue: Drop the special locking rule for worker->flags and worker_pool->flags 2023-08-07 15:57:22 -10:00
workqueue.c As usual, lots of singleton and doubleton patches all over the tree and 2023-11-02 20:53:31 -10:00