This is a note to let you know that I've just added the patch titled tracing: Wake up ring buffer waiters on closing of the file to the 5.19-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: tracing-wake-up-ring-buffer-waiters-on-closing-of-the-file.patch and it can be found in the queue-5.19 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From f3ddb74ad0790030c9592229fb14d8c451f4e9a8 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Google)" <rostedt@xxxxxxxxxxx> Date: Tue, 27 Sep 2022 19:15:27 -0400 Subject: tracing: Wake up ring buffer waiters on closing of the file From: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx> commit f3ddb74ad0790030c9592229fb14d8c451f4e9a8 upstream. When the file that represents the ring buffer is closed, there may be waiters waiting on more input from the ring buffer. Call ring_buffer_wake_waiters() to wake up any waiters when the file is closed. Link: https://lkml.kernel.org/r/20220927231825.182416969@xxxxxxxxxxx Cc: stable@xxxxxxxxxxxxxxx Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Fixes: e30f53aad2202 ("tracing: Do not busy wait in buffer splice") Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- include/linux/trace_events.h | 1 + kernel/trace/trace.c | 15 +++++++++++++++ 2 files changed, 16 insertions(+) --- a/include/linux/trace_events.h +++ b/include/linux/trace_events.h @@ -92,6 +92,7 @@ struct trace_iterator { unsigned int temp_size; char *fmt; /* modified format holder */ unsigned int fmt_size; + long wait_index; /* trace_seq for __print_flags() and __print_symbolic() etc. */ struct trace_seq tmp_seq; --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -8160,6 +8160,12 @@ static int tracing_buffers_release(struc __trace_array_put(iter->tr); + iter->wait_index++; + /* Make sure the waiters see the new wait_index */ + smp_wmb(); + + ring_buffer_wake_waiters(iter->array_buffer->buffer, iter->cpu_file); + if (info->spare) ring_buffer_free_read_page(iter->array_buffer->buffer, info->spare_cpu, info->spare); @@ -8313,6 +8319,8 @@ tracing_buffers_splice_read(struct file /* did we read anything? */ if (!spd.nr_pages) { + long wait_index; + if (ret) goto out; @@ -8320,10 +8328,17 @@ tracing_buffers_splice_read(struct file if ((file->f_flags & O_NONBLOCK) || (flags & SPLICE_F_NONBLOCK)) goto out; + wait_index = READ_ONCE(iter->wait_index); + ret = wait_on_pipe(iter, iter->tr->buffer_percent); if (ret) goto out; + /* Make sure we see the new wait_index */ + smp_rmb(); + if (wait_index != iter->wait_index) + goto out; + goto again; } Patches currently in stable-queue which might be from rostedt@xxxxxxxxxxx are queue-5.19/tracing-fix-reading-strings-from-synthetic-events.patch queue-5.19/tracing-add-ioctl-to-force-ring-buffer-waiters-to-wake-up.patch queue-5.19/ring-buffer-have-the-shortest_full-queue-be-the-shortest-not-longest.patch queue-5.19/ring-buffer-add-ring_buffer_wake_waiters.patch queue-5.19/tracing-move-duplicate-code-of-trace_kprobe-eprobe.c-into-header.patch queue-5.19/tracing-add-fault-name-injection-to-kernel-probes.patch queue-5.19/ring-buffer-fix-race-between-reset-page-and-reading-page.patch queue-5.19/tracing-wake-up-ring-buffer-waiters-on-closing-of-the-file.patch queue-5.19/ftrace-still-disable-enabled-records-marked-as-disabled.patch queue-5.19/tracing-disable-interrupt-or-preemption-before-acquiring-arch_spinlock_t.patch queue-5.19/tracing-do-not-free-snapshot-if-tracer-is-on-cmdline.patch queue-5.19/tracing-wake-up-waiters-when-tracing-is-disabled.patch queue-5.19/ring-buffer-allow-splice-to-read-previous-partially-read-pages.patch queue-5.19/ring-buffer-check-pending-waiters-when-doing-wake-ups-as-well.patch queue-5.19/ftrace-properly-unset-ftrace_hash_fl_mod.patch