[PATCH 04/11] tracing: tracing_buffers_splice_read: behave as-if non-blocking I/O
From: Ahelenia Ziemiańska <hidden>
Date: 2023-10-16 20:36:07
Also in:
lkml
Subsystem:
the rest, tracing · Maintainers:
Linus Torvalds, Steven Rostedt, Masami Hiramatsu
Otherwise we risk sleeping with the pipe locked for indeterminate lengths of time. Link: https://lore.kernel.org/linux-fsdevel/qk6hjuam54khlaikf2ssom6custxf5is2ekkaequf4hvode3ls@zgf7j5j4ubvw/t/#u (local) Signed-off-by: Ahelenia Ziemiańska <redacted> --- kernel/trace/trace.c | 32 ++++---------------------------- 1 file changed, 4 insertions(+), 28 deletions(-)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index abaaf516fcae..9be7a4c0a3ca 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c@@ -8477,7 +8477,6 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos, if (splice_grow_spd(pipe, &spd)) return -ENOMEM; - again: trace_access_lock(iter->cpu_file); entries = ring_buffer_entries_cpu(iter->array_buffer->buffer, iter->cpu_file);
@@ -8528,35 +8527,12 @@ 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; - - ret = -EAGAIN; - 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; - - /* No need to wait after waking up when tracing is off */ - if (!tracer_tracing_is_on(iter->tr)) - goto out; - - /* Make sure we see the new wait_index */ - smp_rmb(); - if (wait_index != iter->wait_index) - goto out; - - goto again; + if (!ret) + ret = -EAGAIN; + } else { + ret = splice_to_pipe(pipe, &spd); } - ret = splice_to_pipe(pipe, &spd); -out: splice_shrink_spd(&spd); return ret;
--
2.39.2Attachments
- signature.asc [application/pgp-signature] 833 bytes