Thread (2 messages) flat view 2 messages, 2 authors, 21d ago
COLD21d

[PATCH] tracing: Fix comment in tracing_buffers_splice_read()

From: Steven Rostedt <rostedt@goodmis.org>
Date: 2026-09-04 18:47:59
Also in: lkml
Subsystem: the rest, tracing · Maintainers: Linus Torvalds, Steven Rostedt, Masami Hiramatsu

From: Steven Rostedt <rostedt@goodmis.org>

The comment about returning an error if the read fails on the first
iteration is slightly incorrect. It makes it sound like the only reason it
could fail on a later iteration is if the subbuf order changed. That is
incorrect, it could also fail if the length passed in was not a multiple
of the subbuf size. Fix the comment.

Link: https://lore.kernel.org/all/20260904143527.40e73d36@gandalf.local.home/ (local)
Fixes: TBD
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
 kernel/trace/trace.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index b26c4c277ce5..8658cad53cb5 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -7296,11 +7296,13 @@ ssize_t tracing_buffers_splice_read(struct file *file, loff_t *ppos,
 			r = ring_buffer_read_page(ref->buffer, ref->rpage, len, iter->cpu_file, 1);
 		} else if (!i) {
 			/*
-			 * We failed to read because the length is too small
-			 * or unaligned. If this is the first iteration, it's
-			 * an invalid userspace input. Otherwise, this is due
-			 * to a subbuf order change. Do not report an error
-			 * and just finish the read.
+			 * If this fails to read on the first iteration, it
+			 * means the length was too small and an error should
+			 * be returned to user space. Otherwise, at least
+			 * one sub-buffer was successfully read but this failed
+			 * due to either the length was unaligned or the
+			 * subbuf order changed. Either case, do not report
+			 * an error.
 			 */
 			ret = -EINVAL;
 		}
-- 
2.53.0
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