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Steven Rostedt (Google) 2aa043a55b tracing/ring-buffer: Fix wait_on_pipe() race 
When the trace_pipe_raw file is closed, there should be no new readers on
the file descriptor. This is mostly handled with the waking and wait_index
fields of the iterator. But there's still a slight race.

     CPU 0                              CPU 1
     -----                              -----
                                   wait_index++;
   index = wait_index;
                                   ring_buffer_wake_waiters();
   wait_on_pipe()
     ring_buffer_wait();

The ring_buffer_wait() will miss the wakeup from CPU 1. The problem is
that the ring_buffer_wait() needs the logic of:

        prepare_to_wait();
        if (!condition)
                schedule();

Where the missing condition check is the iter->wait_index update.

Have the ring_buffer_wait() take a conditional callback function and a
data parameter that can be used within the wait_event_interruptible() of
the ring_buffer_wait() function.

In wait_on_pipe(), pass a condition function that will check if the
wait_index has been updated, if it has, it will return true to break out
of the wait_event_interruptible() loop.

Create a new field "closed" in the trace_iterator and set it in the
.flush() callback before calling ring_buffer_wake_waiters().
This will keep any new readers from waiting on a closed file descriptor.

Have the wait_on_pipe() condition callback also check the closed field.

Change the wait_index field of the trace_iterator to atomic_t. There's no
reason it needs to be 'long' and making it atomic and using
atomic_read_acquire() and atomic_fetch_inc_release() will provide the
necessary memory barriers.

Add a "woken" flag to tracing_buffers_splice_read() to exit the loop after
one more try to fetch data. That is, if it waited for data and something
woke it up, it should try to collect any new data and then exit back to
user space.

Link: https://lore.kernel.org/linux-trace-kernel/CAHk-=wgsNgewHFxZAJiAQznwPMqEtQmi1waeS2O1v6L4c_Um5A@mail.gmail.com/
Link: https://lore.kernel.org/linux-trace-kernel/20240312121703.557950713@goodmis.org

Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linke li <lilinke99@qq.com>
Cc: Rabin Vincent <rabin@rab.in>
Fixes: f3ddb74ad0 ("tracing: Wake up ring buffer waiters on closing of the file")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
 		2024-03-12 12:44:48 -04:00
..
bpf bpf: enforce types for __arg_ctx-tagged arguments in global subprogs 2024-01-17 20:20:06 -08:00
cgroup Driver core changes for 6.8-rc1 2024-01-18 09:48:40 -08:00
configs hardening: Provide Kconfig fragments for basic options 2023-09-22 09:50:55 -07:00
debug kdb: Fix a potential buffer overflow in kdb_local() 2024-01-17 17:19:06 +00:00
dma dma-mapping fixes for Linux 6.8 2024-01-18 16:49:34 -08:00
entry entry: Move syscall_enter_from_user_mode() to header file 2023-12-21 23:12:18 +01:00
events uprobes: use pagesize-aligned virtual address when replacing pages 2024-01-25 23:52:20 -08:00
futex futex: Prevent the reuse of stale pi_state 2024-01-19 12:58:17 +01:00
gcov gcov: annotate struct gcov_iterator with __counted_by 2023-10-18 14:43:22 -07:00
irq genirq: Initialize resend_node hlist for all interrupt descriptors 2024-01-24 14:15:41 +01:00
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 v6.8 2024-01-12 16:35:58 -08:00
module Modules changes for v6.8-rc1 2024-01-10 18:00:18 -08:00
power PM: hibernate: Repair excess function parameter description warning 2023-12-20 19:19:26 +01:00
printk TTY/Serial changes for 6.7-rc1 2023-11-03 15:44:25 -10:00
rcu rcu: Defer RCU kthreads wakeup when CPU is dying 2024-01-24 22:46:17 +05:30
sched Fix a cpufreq related performance regression on certain systems, 2024-01-18 11:57:33 -08:00
time hrtimer: Report offline hrtimer enqueue 2024-02-06 10:56:35 +01:00
trace tracing/ring-buffer: Fix wait_on_pipe() race 2024-03-12 12:44:48 -04:00
.gitignore
…
Kconfig.freezer
…
Kconfig.hz
…
Kconfig.kexec kexec: select CRYPTO from KEXEC_FILE instead of depending on it 2023-12-20 13:46:19 -08:00
Kconfig.locks
…
Kconfig.preempt
…
Makefile kernel/numa.c: Move logging out of numa.h 2023-12-20 19:26:30 -05:00
acct.c fs: rename __mnt_{want,drop}_write*() helpers 2023-09-11 15:05:50 +02:00
async.c header cleanups for 6.8 2024-01-10 16:43:55 -08:00
audit.c audit: Send netlink ACK before setting connection in auditd_set 2023-11-12 22:33:49 -05:00
audit.h audit: correct audit_filter_inodes() definition 2023-07-21 12:17:25 -04:00
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
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
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bounds.c
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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.c slab updates for 6.8 2024-01-09 10:36:07 -08:00
cpu_pm.c
…
crash_core.c kernel/crash_core.c: make __crash_hotplug_lock static 2024-01-12 15:20:47 -08:00
crash_dump.c
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cred.c cred: get rid of CONFIG_DEBUG_CREDENTIALS 2023-12-15 14:19:48 -08:00
delayacct.c delayacct: track delays from IRQ/SOFTIRQ 2023-04-18 16:39:34 -07:00
dma.c
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exec_domain.c
…
exit.c exit: wait_task_zombie: kill the no longer necessary spin_lock_irq(siglock) 2024-02-07 21:20:33 -08:00
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 exec: Distinguish in_execve from in_exec 2024-01-24 11:48:52 -08:00
freezer.c Linux 6.7-rc6 2023-12-23 15:52:13 +01:00
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
…
kallsyms.c kallsyms: Change func signature for cleanup_symbol_name() 2023-08-25 15:00:36 -07:00
kallsyms_internal.h
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kallsyms_selftest.c Modules changes for v6.6-rc1 2023-08-29 17:32:32 -07:00
kallsyms_selftest.h
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kcmp.c file: convert to SLAB_TYPESAFE_BY_RCU 2023-10-19 11:02:48 +02:00
kcov.c kcov: add prototypes for helper functions 2023-06-09 17:44:17 -07:00
kexec.c kernel: kexec: copy user-array safely 2023-10-09 16:59:47 +10:00
kexec_core.c kexec: do syscore_shutdown() in kernel_kexec 2024-01-12 15:20:47 -08:00
kexec_elf.c
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kexec_file.c kexec_file: fix incorrect temp_start value in locate_mem_hole_top_down() 2023-12-29 12:22:25 -08:00
kexec_internal.h
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kheaders.c kheaders: Use array declaration instead of char 2023-03-24 20:10:59 -07:00
kprobes.c kprobes: Remove unnecessary initial values of variables 2024-02-08 23:29:29 +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
…
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
numa.c kernel/numa.c: Move logging out of numa.h 2023-12-20 19:26:30 -05:00
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 params: Fix multi-line comment style 2023-12-01 09:51:44 -08:00
pid.c file: remove __receive_fd() 2023-12-12 14:24:14 +01:00
pid_namespace.c wait: Remove uapi header file from main header file 2023-12-20 19:26:31 -05:00
pid_sysctl.h memfd: replace ratcheting feature from vm.memfd_noexec with hierarchy 2023-08-21 13:37:59 -07:00
profile.c
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ptrace.c Quite a lot of kexec work this time around. Many singleton patches in 2024-01-09 11:46:20 -08:00
range.c
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reboot.c Thermal control updates for 6.8-rc1 2024-01-09 16:20:17 -08:00
regset.c
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relay.c kernel: relay: remove relay_file_splice_read dead code, doesn't work 2023-12-29 12:22:27 -08:00
resource.c Quite a lot of kexec work this time around. Many singleton patches in 2024-01-09 11:46:20 -08:00
resource_kunit.c
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rseq.c
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scftorture.c scftorture: Pause testing after memory-allocation failure 2023-07-14 15:02:57 -07:00
scs.c
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seccomp.c file: remove __receive_fd() 2023-12-12 14:24:14 +01:00
signal.c kernel/signal.c: simplify force_sig_info_to_task(), kill recalc_sigpending_and_wake() 2023-12-10 17:21:32 -08:00
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
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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: fix kernel-doc typo 2023-12-29 12:22:29 -08:00
static_call.c
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static_call_inline.c
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stop_machine.c
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sys.c getrusage: use sig->stats_lock rather than lock_task_sighand() 2024-02-07 21:20:32 -08:00
sys_ni.c lsm/stable-6.8 PR 20240105 2024-01-09 12:57:46 -08:00
sysctl-test.c
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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
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ucount.c sysctl: Add size to register_sysctl 2023-08-15 15:26:17 -07:00
uid16.c
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uid16.h
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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-return-notifier.c
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user.c binfmt_misc: enable sandboxed mounts 2023-10-11 08:46:01 -07:00
user_namespace.c mnt_idmapping: decouple from namespaces 2023-11-28 14:08:47 +01:00
usermode_driver.c
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utsname.c
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utsname_sysctl.c utsname: simplify one-level sysctl registration for uts_kern_table 2023-04-13 11:49:35 -07:00
vhost_task.c vhost: Fix worker hangs due to missed wake up calls 2023-06-08 15:43:09 -04:00
watch_queue.c watch_queue: fix kcalloc() arguments order 2023-12-21 13:17:54 +01:00
watchdog.c watchdog: if panicking and we dumped everything, don't re-enable dumping 2023-12-29 12:22:30 -08:00
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
workqueue.c Revert "workqueue: Override implicit ordered attribute in workqueue_apply_unbound_cpumask()" 2024-02-05 15:49:06 -10:00
workqueue_internal.h workqueue: Drop the special locking rule for worker->flags and worker_pool->flags 2023-08-07 15:57:22 -10:00