From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id ABF2846EC95 for ; Fri, 14 Aug 2026 12:41:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786711293; cv=none; b=k2/I9F56DVJsS3Z1GHLrtW1tR1Ywivw+T3KrP3prxEqdduiH9G3KHdMPt3lEf1f0Fvc1rFUxg6IP96j4Uf75qN2gT4xyCawFWSzuhasbFmDeurlyH62QP7IwGNXm/tVychT6C2Y25vf3XqXTyd+JceScDAbCDX6bAbiuqxxYka4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786711293; c=relaxed/simple; bh=SKhvFGVw4DdnbhHxAqTGiyJNC3LTiY5uW+1yta5aPDg=; h=Message-ID:Date:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=UKQcCYseDP8OKJDDVMOIFyYHwD/dYbagF1NyFWVhforYi7jUKD9/bhX66gP3pV2ZFYIX/TX3jSmlLH9nlSFFjbNzsgzJRS8ueNE8vPNQ0j8qFj1jpjqklvf4s57/pSW1BbXbgTHG6pMwRZUhL8Xg8iGEtr36qQQ5+gGKui/26ag= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=SJAb37Fp; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="SJAb37Fp" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 795461F00ADE; Fri, 14 Aug 2026 12:41:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1786711284; bh=OXNPe/FGNewPuKZStiOfZOcX2GUk1kB2Duf3ynAArYo=; h=Date:From:To:Cc:Subject:References; b=SJAb37Fpor8MjAIRUA5hPW4IAFpEem4aU0TIAOa36RlWXJermj8TNaWGToMnBjBQt FzDn3gXUkHyVUY97sQuje77nX/l3NlDgFiWUEIg/uiKESot5vWH2jCHnxn8KTfOP9B FbWgnAF2Yi4WixJiuiqFJyVALUYrFQ4dUOY9EURRLFVhdLteOh3GAvzWfrjUNWmsOh Z5sNj7h0EuexKaPJqJlhEltyMjKcaEtnQfKyKNHiaStNhLAa304lV4kTKiH8NbtqDx aTUTZ9clfMUA/fdZDDgM/w+cxIhyof0Tw+2n007JZUm5xMQ2B0/vJxssjSyjzlwR0e r4HpVVjNayGHg== Received: from rostedt by gandalf with local (Exim 4.99.4) (envelope-from ) id 1wurEE-00000003zoI-3mnH; Fri, 14 Aug 2026 08:41:42 -0400 Message-ID: <20260814124142.757403608@kernel.org> User-Agent: quilt/0.69 Date: Fri, 14 Aug 2026 08:41:32 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , Andrew Morton , Vincent Donnefort Subject: [for-next][PATCH 9/9] ring-buffer: Remove ring_buffer_per_cpu::mapped References: <20260814124123.133362396@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 From: Vincent Donnefort ring_buffer_per_cpu::mapped tracks if a ring-buffer is either mapped by user-space or if it is a persistent buffer. We already have user_mapped for the former and ring_meta for the latter. Get rid of mapped and instead create rb_is_static(). A static ring-buffer cannot be resized, swapped or have its pages extracted. Link: https://patch.msgid.link/20260813131152.3589632-10-vdonnefort@google.com Signed-off-by: Vincent Donnefort Signed-off-by: Steven Rostedt --- kernel/trace/ring_buffer.c | 45 ++++++++++++++------------------------ 1 file changed, 17 insertions(+), 28 deletions(-) diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index f75aafc755bd..5fc009edc1ec 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -514,7 +514,7 @@ struct ring_buffer_per_cpu { int cpu; atomic_t record_disabled; atomic_t resize_disabled; - struct trace_buffer *buffer; + struct trace_buffer *buffer; raw_spinlock_t reader_lock; /* serialize readers */ arch_spinlock_t lock; struct lock_class_key lock_key; @@ -552,7 +552,6 @@ struct ring_buffer_per_cpu { /* pages removed since last reset */ unsigned long pages_removed; - unsigned int mapped; unsigned int user_mapped; /* user space mapping */ struct mutex mapping_lock; struct buffer_page **subbuf_ids; /* ID to subbuf VA */ @@ -648,6 +647,11 @@ unsigned long rb_subbuf_start(struct trace_buffer *buffer, unsigned long addr) return addr & ~((unsigned long)(rb_subbuf_size(buffer) - 1)); } +static bool rb_is_static(struct ring_buffer_per_cpu *cpu_buffer) +{ + return cpu_buffer->user_mapped || cpu_buffer->remote || cpu_buffer->ring_meta; +} + struct ring_buffer_iter { struct ring_buffer_per_cpu *cpu_buffer; unsigned long head; @@ -2578,7 +2582,6 @@ rb_allocate_cpu_buffer(struct trace_buffer *buffer, long nr_pages, int cpu) * Range mapped buffers have the same restrictions as memory * mapped ones do. */ - cpu_buffer->mapped = 1; cpu_buffer->ring_meta = rb_range_meta(buffer, nr_pages, cpu); bpage->page = rb_range_buffer(cpu_buffer, 0); if (!bpage->page) @@ -6667,12 +6670,11 @@ rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer) rb_head_page_activate(cpu_buffer); cpu_buffer->pages_removed = 0; - if (cpu_buffer->mapped) { - rb_update_meta_page(cpu_buffer); - if (cpu_buffer->ring_meta) { - struct ring_buffer_cpu_meta *meta = cpu_buffer->ring_meta; - meta->commit_buffer = meta->head_buffer; - } + rb_update_meta_page(cpu_buffer); + if (cpu_buffer->ring_meta) { + struct ring_buffer_cpu_meta *meta = cpu_buffer->ring_meta; + + meta->commit_buffer = meta->head_buffer; } } @@ -6921,8 +6923,8 @@ int ring_buffer_swap_cpu(struct trace_buffer *buffer_a, cpu_buffer_a = buffer_a->buffers[cpu]; cpu_buffer_b = buffer_b->buffers[cpu]; - /* It's up to the callers to not try to swap mapped buffers */ - if (WARN_ON_ONCE(cpu_buffer_a->mapped || cpu_buffer_b->mapped)) + /* It's up to the callers to not try to swap static buffers */ + if (WARN_ON_ONCE(rb_is_static(cpu_buffer_a) || rb_is_static(cpu_buffer_b))) return -EBUSY; /* At least make sure the two buffers are somewhat the same */ @@ -7134,7 +7136,6 @@ int ring_buffer_read_page(struct trace_buffer *buffer, unsigned int size; unsigned int read; u64 save_timestamp; - bool force_memcpy; if (!cpumask_test_cpu(cpu, buffer->cpumask)) return -1; @@ -7173,8 +7174,6 @@ int ring_buffer_read_page(struct trace_buffer *buffer, /* Check if any events were dropped */ missed_events = cpu_buffer->lost_events; - force_memcpy = cpu_buffer->mapped || cpu_buffer->remote; - /* * If this page has been partially read or * if len is not big enough to read the rest of the page or @@ -7184,7 +7183,7 @@ int ring_buffer_read_page(struct trace_buffer *buffer, */ if (read || (len < (size - read)) || cpu_buffer->reader_page == cpu_buffer->commit_page || - force_memcpy) { + rb_is_static(cpu_buffer)) { struct buffer_data_page *rpage = cpu_buffer->reader_page->page; unsigned int rpos = read; unsigned int pos = 0; @@ -7633,11 +7632,7 @@ static int __rb_inc_dec_mapped(struct ring_buffer_per_cpu *cpu_buffer, lockdep_assert_held(&cpu_buffer->mapping_lock); - /* mapped is always greater or equal to user_mapped */ - if (WARN_ON(cpu_buffer->mapped < cpu_buffer->user_mapped)) - return -EINVAL; - - if (inc && cpu_buffer->mapped == UINT_MAX) + if (inc && cpu_buffer->user_mapped == UINT_MAX) return -EBUSY; if (WARN_ON(!inc && cpu_buffer->user_mapped == 0)) @@ -7646,13 +7641,10 @@ static int __rb_inc_dec_mapped(struct ring_buffer_per_cpu *cpu_buffer, mutex_lock(&cpu_buffer->buffer->mutex); raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); - if (inc) { + if (inc) cpu_buffer->user_mapped++; - cpu_buffer->mapped++; - } else { + else cpu_buffer->user_mapped--; - cpu_buffer->mapped--; - } raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); mutex_unlock(&cpu_buffer->buffer->mutex); @@ -7824,7 +7816,6 @@ int ring_buffer_map(struct trace_buffer *buffer, int cpu, if (!err) { raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); /* This is the first time it is mapped by user */ - cpu_buffer->mapped++; cpu_buffer->user_mapped = 1; raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); } else { @@ -7881,8 +7872,6 @@ int ring_buffer_unmap(struct trace_buffer *buffer, int cpu) raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); /* This is the last user space mapping */ - if (!WARN_ON_ONCE(cpu_buffer->mapped < cpu_buffer->user_mapped)) - cpu_buffer->mapped--; cpu_buffer->user_mapped = 0; raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); -- 2.53.0