John Ogness 5f72e52ba9 printk: ringbuffer: Do not skip non-finalized records with prb_next_seq() ... Commit f244b4dc53 ("printk: ringbuffer: Improve prb_next_seq() performance") introduced an optimization for prb_next_seq() by using best-effort to track recently finalized records. However, the order of finalization does not necessarily match the order of the records. The optimization changed prb_next_seq() to return inconsistent results, possibly yielding sequence numbers that are not available to readers because they are preceded by non-finalized records or they are not yet visible to the reader CPU. Rather than simply best-effort tracking recently finalized records, force the committing writer to read records and increment the last "contiguous block" of finalized records. In order to do this, the sequence number instead of ID must be stored because ID's cannot be directly compared. A new memory barrier pair is introduced to guarantee that a reader can always read the records up until the sequence number returned by prb_next_seq() (unless the records have since been overwritten in the ringbuffer). This restores the original functionality of prb_next_seq() while also keeping the optimization. For 32bit systems, only the lower 32 bits of the sequence number are stored. When reading the value, it is expanded to the full 64bit sequence number using the 32bit seq macros, which fold in the value returned by prb_first_seq(). Fixes: f244b4dc53 ("printk: ringbuffer: Improve prb_next_seq() performance") Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20240207134103.1357162-5-john.ogness@linutronix.de Signed-off-by: Petr Mladek <pmladek@suse.com>		2024-02-07 17:23:18 +01:00
..
bpf	for-6.7/io_uring-sockopt-2023-10-30	2023-11-01 11:16:34 -10:00
cgroup	Many singleton patches against the MM code. The patch series which are	2023-11-02 19:38:47 -10:00
configs	hardening: Provide Kconfig fragments for basic options	2023-09-22 09:50:55 -07:00
debug	printk changes for 6.6	2023-09-04 13:20:19 -07:00
dma	dma-mapping updates for Linux 6.7	2023-11-01 13:15:54 -10:00
entry	entry: Remove empty addr_limit_user_check()	2023-08-23 10:32:39 +02:00
events	Many singleton patches against the MM code. The patch series which are	2023-11-02 19:38:47 -10:00
futex	io_uring-futex-2023-10-30	2023-11-01 11:25:08 -10:00
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	printk: ringbuffer: Do not skip non-finalized records with prb_next_seq()	2024-02-07 17:23:18 +01:00
rcu	Many singleton patches against the MM code. The patch series which are	2023-11-02 19:38:47 -10:00
sched	As usual, lots of singleton and doubleton patches all over the tree and	2023-11-02 20:53:31 -10:00
time	Networking changes for 6.7.	2023-10-31 05:10:11 -10:00
trace	Probes updates for v6.7:	2023-11-01 16:15:42 -10:00
.gitignore	…
Kconfig.freezer	…
Kconfig.hz	…
Kconfig.kexec	docs: fix link s390/zfcpdump.rst	2023-10-04 10:41:56 -07:00
Kconfig.locks	…
Kconfig.preempt	…
Makefile	…
acct.c	fs: rename __mnt_{want,drop}_write*() helpers	2023-09-11 15:05:50 +02:00
async.c	…
audit.c	audit: move trailing statements to next line	2023-08-15 18:16:14 -04:00
audit.h	…
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 take task_lock() in audit_exe_compare() code path	2023-10-25 22:29:47 -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	…
cfi.c	…
compat.c	…
configs.c	…
context_tracking.c	…
cpu.c	asm-generic updates for v6.7	2023-11-01 15:28:33 -10:00
cpu_pm.c	…
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	…
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	…
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	…
groups.c	groups: Convert group_info.usage to refcount_t	2023-09-29 11:28:39 -07:00
hung_task.c	…
iomem.c	kernel/iomem.c: remove __weak ioremap_cache helper	2023-08-21 13:37:28 -07:00
irq_work.c	…
jump_label.c	…
kallsyms.c	kallsyms: Change func signature for cleanup_symbol_name()	2023-08-25 15:00:36 -07:00
kallsyms_internal.h	…
kallsyms_selftest.c	Modules changes for v6.6-rc1	2023-08-29 17:32:32 -07:00
kallsyms_selftest.h	…
kcmp.c	file: convert to SLAB_TYPESAFE_BY_RCU	2023-10-19 11:02:48 +02:00
kcov.c	…
kexec.c	kernel: kexec: copy user-array safely	2023-10-09 16:59:47 +10:00
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	…
kheaders.c	…
kprobes.c	kprobes: kretprobe scalability improvement	2023-10-18 23:59:54 +09:00
ksyms_common.c	…
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	…
module_signature.c	…
notifier.c	…
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	…
pid.c	pidfd: prevent a kernel-doc warning	2023-09-19 13:21:33 -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
profile.c	…
ptrace.c	mm: make __access_remote_vm() static	2023-10-18 14:34:15 -07:00
range.c	…
reboot.c	…
regset.c	…
relay.c	kernel: relay: remove unnecessary NULL values from relay_open_buf	2023-08-18 10:18:55 -07:00
resource.c	…
resource_kunit.c	…
rseq.c	…
scftorture.c	…
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	…
stackleak.c	…
stacktrace.c	stacktrace: Export stack_trace_save_tsk	2023-09-11 23:59:47 -04:00
static_call.c	…
static_call_inline.c	…
stop_machine.c	…
sys.c	As usual, lots of singleton and doubleton patches all over the tree and	2023-11-02 20:53:31 -10:00
sys_ni.c	asm-generic updates for v6.7	2023-11-01 15:28:33 -10:00
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	…
tsacct.c	…
ucount.c	sysctl: Add size to register_sysctl	2023-08-15 15:26:17 -07:00
uid16.c	…
uid16.h	…
umh.c	…
up.c	smp: Change function signatures to use call_single_data_t	2023-09-13 14:59:24 +02:00
user-return-notifier.c	…
user.c	binfmt_misc: enable sandboxed mounts	2023-10-11 08:46:01 -07:00
user_namespace.c	As usual, lots of singleton and doubleton patches all over the tree and	2023-11-02 20:53:31 -10:00
usermode_driver.c	…
utsname.c	…
utsname_sysctl.c	…
vhost_task.c	…
watch_queue.c	kernel: watch_queue: copy user-array safely	2023-10-09 16:59:48 +10:00
watchdog.c	watchdog: move softlockup_panic back to early_param	2023-11-01 12:10:02 -07:00
watchdog_buddy.c	…
watchdog_perf.c	…
workqueue.c	As usual, lots of singleton and doubleton patches all over the tree and	2023-11-02 20:53:31 -10:00
workqueue_internal.h	…