From: Vincent Donnefort <vdonnefort@google.com>
To: rostedt@goodmis.org, mhiramat@kernel.org,
linux-trace-kernel@vger.kernel.org
Cc: mathieu.desnoyers@efficios.com, kernel-team@android.com,
linux-kernel@vger.kernel.org,
Vincent Donnefort <vdonnefort@google.com>
Subject: [PATCH v8 15/21] tracing/remotes: Use ring_buffer_capacity() in trace_remote_has_cpu()
Date: Fri, 6 Nov 2026 18:06:51 +0000 [thread overview]
Message-ID: <20261106180657.2460376-16-vdonnefort@google.com> (raw)
In-Reply-To: <20261106180657.2460376-1-vdonnefort@google.com>
trace_remote_has_cpu() calls ring_buffer_poll_remote() only to check if
a CPU is in the trace_buffer cpumask, needlessly polling the meta-page
and waking up readers. Use ring_buffer_capacity() instead to check CPU
membership without taking reader_lock or triggering wakeups.
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
---
kernel/trace/trace_remote.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/trace/trace_remote.c b/kernel/trace/trace_remote.c
index 3dbb4912dbd6..276bf94e837b 100644
--- a/kernel/trace/trace_remote.c
+++ b/kernel/trace/trace_remote.c
@@ -351,7 +351,7 @@ static bool trace_remote_has_cpu(struct trace_remote *remote, int cpu)
if (cpu == RING_BUFFER_ALL_CPUS)
return true;
- return ring_buffer_poll_remote(remote->trace_buffer, cpu) == 0;
+ return ring_buffer_capacity(remote->trace_buffer, cpu) > 0;
}
static void __free_ring_buffer_iter(struct trace_remote_iterator *iter, int cpu)
--
2.56.0.455.g6c5a503b38-goog
next prev parent reply other threads:[~2026-11-06 18:08 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-06 18:06 [PATCH v8 00/21] tracing/remotes: Add printk, dump_on_panic and boot parameters Vincent Donnefort
2026-11-06 18:06 ` [PATCH v8 01/21] tracing/remotes: Gate tracefs files opening on trace remote registration Vincent Donnefort
2026-11-06 18:06 ` [PATCH v8 02/21] tracing/remotes: Release tracefs,eventfs on registration failure Vincent Donnefort
2026-11-06 18:06 ` [PATCH v8 03/21] tracing/remotes: Use kstrtobool for boolean tracefs files Vincent Donnefort
2026-11-06 18:06 ` [PATCH v8 04/21] tracing/remotes: Initialise pos in trace_start() Vincent Donnefort
2026-11-06 18:06 ` [PATCH v8 05/21] tracing/remotes: Annotate remote shared fields with READ_ONCE/WRITE_ONCE Vincent Donnefort
2026-11-06 18:06 ` [PATCH v8 06/21] tracing/remotes: Use a single per-remote polling work Vincent Donnefort
2026-11-06 18:06 ` [PATCH v8 07/21] tracing/simple_ring_buffer: Add support for compressed length Vincent Donnefort
2026-11-06 18:06 ` [PATCH v8 08/21] tracing/remotes: Add dmesg tracefs file Vincent Donnefort
2026-11-06 18:06 ` [PATCH v8 09/21] tracing/remotes: selftests: Add a test for the " Vincent Donnefort
2026-11-06 18:06 ` [PATCH v8 10/21] tracing/remotes: selftests: Prefix hypervisor folder Vincent Donnefort
2026-11-06 18:06 ` [PATCH v8 11/21] ring-buffer: Use irqsave for the reader lock in ring_buffer_poll_remote Vincent Donnefort
2026-11-06 18:06 ` [PATCH v8 12/21] ring-buffer: Avoid reader_lock deadlock during panic Vincent Donnefort
2026-11-06 18:06 ` [PATCH v8 13/21] ring-buffer: Use panic-friendly locking in ring_buffer_iter interface Vincent Donnefort
2026-11-06 18:06 ` [PATCH v8 14/21] ring-buffer: Add kerneldoc for ring_buffer_poll_remote Vincent Donnefort
2026-11-06 18:06 ` Vincent Donnefort [this message]
2026-11-06 18:06 ` [PATCH v8 16/21] tracing/remotes: Add dump_on_panic tracefs file Vincent Donnefort
2026-11-06 18:06 ` [PATCH v8 17/21] tracing/remotes: selftests: Add a test for the " Vincent Donnefort
2026-11-06 18:06 ` [PATCH v8 18/21] tracing/remotes: Add poll_ms " Vincent Donnefort
2026-11-06 18:06 ` [PATCH v8 19/21] tracing/remotes: Add trace_remote cmdline options Vincent Donnefort
2026-11-06 18:06 ` [PATCH v8 20/21] Documentation: tracing/remotes: Add detailed tracefs layout Vincent Donnefort
2026-11-06 18:06 ` [PATCH v8 21/21] Documentation/kernel-parameters: Add trace_remote Vincent Donnefort
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