From 2475de2bc0de17fb1b24c5e90194f84b5ca70d3e Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Google)" Date: Tue, 27 Sep 2022 19:15:27 -0400 Subject: [PATCH] tracing: Wake up ring buffer waiters on closing of the file 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@goodmis.org Cc: stable@vger.kernel.org Cc: Ingo Molnar Cc: Andrew Morton Fixes: e30f53aad2202 ("tracing: Do not busy wait in buffer splice") Signed-off-by: Steven Rostedt (Google) Signed-off-by: Greg Kroah-Hartman --- include/linux/trace_events.h | 1 + kernel/trace/trace.c | 15 +++++++++++++++ 2 files changed, 16 insertions(+) diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h index 57113190448c..ff137179e0c3 100644 --- a/include/linux/trace_events.h +++ b/include/linux/trace_events.h @@ -91,6 +91,7 @@ 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; diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 61090aec498e..bf0b693143d0 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -8117,6 +8117,12 @@ static int tracing_buffers_release(struct inode *inode, struct file *file) __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); @@ -8270,6 +8276,8 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos, /* did we read anything? */ if (!spd.nr_pages) { + long wait_index; + if (ret) goto out; @@ -8277,10 +8285,17 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos, 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; }