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Wed, 04 Nov 2026 15:20:56 -0800 (PST) Received: from localhost ([182.216.53.174]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3b094dec0e3sm2551500a91.1.2026.11.04.15.20.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 04 Nov 2026 15:20:55 -0800 (PST) From: Jaewon Jung To: Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers Cc: sashiko-bot@kernel.org, sashiko-reviews@lists.linux.dev, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Subject: [PATCH v3] tracing: Keep copying markers when one instance is stopped Date: Thu, 5 Nov 2026 08:19:26 +0900 Message-ID: <20261104232046.32519-1-jaewon8868@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20261104085715.5838b869@gandalf.local.home> References: <20261103005219.3236380-1-jaewon8868@gmail.com> <20261103095019.6a88e783@gandalf.local.home> <20261104063552.28094-1-jaewon8868@gmail.com> <20261104085715.5838b869@gandalf.local.home> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit When several instances enable copy_trace_marker, stopping one instance can prevent the remaining buffers from receiving markers. Continue copying text and raw markers even if one copy fails. Return the largest successful write length, or -ENODEV if no write succeeds. Fixes: 7b382efd5e8a ("tracing: Allow the top level trace_marker to write into another instances") Signed-off-by: Jaewon Jung --- Changes in v3: - Return the largest successful write length, as suggested by Steven. Tested on x86_64 QEMU: - Before: A failed copy prevents writes to later live buffers. - After: All buffers are tried, and the largest successful write length is returned. If no write succeeds, ENODEV is returned. - Existing text/raw marker and instance selftests: 6 PASS. kernel/trace/trace.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 08614af8fad1..164da1ea5e73 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -6329,9 +6329,10 @@ tracing_mark_write(struct file *filp, const char __user *ubuf, if (tr == &global_trace) { guard(rcu)(); list_for_each_entry_rcu(tr, &marker_copies, marker_list) { - written = write_marker_to_buffer(tr, buf, cnt, ip); - if (written < 0) - break; + ssize_t w = write_marker_to_buffer(tr, buf, cnt, ip); + + if (w >= 0 && w > written) + written = w; } } else { written = write_marker_to_buffer(tr, buf, cnt, ip); @@ -6408,9 +6409,10 @@ tracing_mark_raw_write(struct file *filp, const char __user *ubuf, if (tr == &global_trace) { guard(rcu)(); list_for_each_entry_rcu(tr, &marker_copies, marker_list) { - written = write_raw_marker_to_buffer(tr, buf, cnt); - if (written < 0) - break; + ssize_t w = write_raw_marker_to_buffer(tr, buf, cnt); + + if (w >= 0 && w > written) + written = w; } } else { written = write_raw_marker_to_buffer(tr, buf, cnt); base-commit: d7ff48d92a0f28bc0612da47c054efbc28c19562 -- 2.43.0