From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f71.google.com (mail-wm1-f71.google.com [209.85.128.71]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9EAC950AC28 for ; Fri, 4 Sep 2026 16:46:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.71 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788540372; cv=none; b=tTAP2QtWM49191GhNJxJd+srCUFCCUnbGtUvFKnbD1IvsIuexJSUe1nytoRIdk99t2GajrPQ5iReb55J5FKEMgoPMu3GTqkrOh18wlSoDV/8t/zHHJzwoGNp4EAXH7ewE0rj2rheBv/CriAGg4cVHkNsO0gnW2WGtdYpGoApjVQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788540372; c=relaxed/simple; bh=hxQZMLwG6yecstcTEMEbqIUKya/zeWZiCbghCJI8fVQ=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=JGJXJIAZgVv+KcuDA4F8jl5Y2t3Nah8oXOTxOBksjsgYQPp9EXLLS0/hzmTsiPfFfz04LlJnlw7GDpz5Ikg3/QxyyvzFJIJ/7ppk49rVChDHCLdvTzNVIJCMrfchOab059p0NxfZ7xoeK1xZRNnWIldHDOu10SmXe9rA0S0cZa0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--vdonnefort.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=vpkXyu6U; arc=none smtp.client-ip=209.85.128.71 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--vdonnefort.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="vpkXyu6U" Received: by mail-wm1-f71.google.com with SMTP id 5b1f17b1804b1-495689bfcc8so9389675e9.1 for ; Fri, 04 Sep 2026 09:46:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1788540360; x=1789145160; darn=vger.kernel.org; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:from:to:cc:subject:date:message-id:reply-to :content-type; bh=vWNAdrwGmNJRf6eRTL3iblh5LCxPTOBo/qfLWNuuaXo=; b=vpkXyu6UIvcaSzsDleZpo1eGIF5yY+lTSnOrIhzO5QZNnnGlE05girF4gH4JixmfzK 50xri6fSK8PczTnr6MUN2GNZ8+fGTML/jfDv+s5+kKvZ++wKj7VArYmCwBJVzY6ok6dI 16uDI+uTmP0Yg6KEbmZgB6sHCemsYvLIbjQB4shpHvkoH7kgDoS2nOWxQZEH2nenm7E+ 3BiM+0fozaacAidqi66ze+841KgVSvmBfvFH4/XaAMuhhVkqchiR0xAUWAbIZzMWhtfe uABTOB/sIUCEkBAEiLLLocP8WBfBR0Pg6ItcfjHhreQXKjyE8b5B+xLeqVYHbYrjOjgY io0g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1788540360; x=1789145160; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=vWNAdrwGmNJRf6eRTL3iblh5LCxPTOBo/qfLWNuuaXo=; b=inqtNwyVInOfTgMnN5DskiCXgCujbm8jBW+H5auOxYv6rT2GezGOKFYVgesr1/xy4c WKhBmfTIJnl0FCkWzyaoph78HniD846JHaMTwYN4cA7igycJPJzwuzUFLxzhVTi3u6qX ylgFXeZRo/rvAS5YZDUbji3siPcNI+X0M42zlth9EbK3TsB8dbcfuDYB/bfmCzQYwEIO cH8MeBhtc9sj0v/e2h2UZOUzUg34n2VBkL1rfV1tM3QXeqW4XacQWICBh9Wts/MDESoj 13Bij22qUaYH5/lET49cxeAXkt7HrRBEpZDu8fIzK5Bl0kY252B7R+45+FXbt+KLvUHG USlQ== X-Forwarded-Encrypted: i=1; AKwUvBwDEM3x0LO/k5nYtm+N3HP7KRZABk8Rb//pnSUys2o1qCfqvgTyYxD3NTg0QA4UtThHQLvhc5P3BSmAYiwXD/aLbog=@vger.kernel.org X-Gm-Message-State: AFuF++kIkH41pbMDdx2EU+LF1fdBPUD2LcpF+4AmnLaHe2zQPNpG7Fo9 9Hac2vjETCEiEUwNARqNoKqRJ+nsMGO6UPnycR+L53pdDBVYG2O0uv0IhkkO+DXWadoP6cG34an CHfwPJ7izk0Gzu2QVHHnlug== X-Received: from wmwb5-n2.prod.google.com ([2002:a05:600d:4445:20b0:49a:1b4c:be]) (user=vdonnefort job=prod-delivery.src-stubby-dispatcher) by 2002:a05:600c:a40f:b0:49c:fa21:e74b with SMTP id 5b1f17b1804b1-49cfa21e9a7mr42587355e9.33.1788540360049; Fri, 04 Sep 2026 09:46:00 -0700 (PDT) Date: Fri, 4 Sep 2026 17:44:47 +0100 In-Reply-To: <20260904164450.1345852-1-vdonnefort@google.com> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260904164450.1345852-1-vdonnefort@google.com> X-Mailer: git-send-email 2.55.0.979.g7e5102b832-goog Message-ID: <20260904164450.1345852-2-vdonnefort@google.com> Subject: [PATCH v10 1/4] ring-buffer: Allow splice reads on static buffers From: Vincent Donnefort 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 Content-Type: text/plain; charset="UTF-8" ring_buffer_read_page() rejects splice (full=1) reads on static buffers (that is user-mapped, persistent or remote) because !read check assumes unread pages must be swapped. However for those buffers we have no other choice than memcpy the data. For the memcpy case, only return an error when the writer is still on the reader page for the splice interface to wait. Fixes: 117c39200d9d ("ring-buffer: Introducing ring-buffer mapping functions") Signed-off-by: Vincent Donnefort diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index b0963ac6fd16..84fd4cdd486f 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -7193,15 +7193,8 @@ int ring_buffer_read_page(struct trace_buffer *buffer, unsigned int event_size; unsigned int flags = 0; - /* - * If a full page is expected, this can still be returned - * if there's been a previous partial read and the - * rest of the page can be read and the commit page is off - * the reader page. - */ - if (full && - (!read || (len < (size - read)) || - cpu_buffer->reader_page == cpu_buffer->commit_page)) + /* If a full page is requested, it cannot be the commit page */ + if (full && cpu_buffer->reader_page == cpu_buffer->commit_page) return -1; if (len > (size - read)) -- 2.55.0.979.g7e5102b832-goog