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 2F73B4B44B1; Thu, 17 Sep 2026 15:37:53 +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=1789659482; cv=none; b=n2GcSfGS61+W6C7e9IskmfW7upBFft3Z7fth+c0BbtnwgmplMIlG5iWYNg+52xK9DgkZedKjUTQnnYnctk5sOYowaiGXzZpcQiRNS9sQWnTejJUUOJtWw+IPFFQzC4gP/J7uPqUS0+RfjkqXGRYtrxUp5kdRPaISYP2nvPUNmd0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789659482; c=relaxed/simple; bh=ikXFhcDv+5T25fL9EF59YHpkJbma8qtVF6bqRV2i9Mo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=DxKaZla4PTZHgnKg4SSD0dLJyg9nUSyM9O1zdBzncwSBjbvC7kdy0CCBkH5Aq2+sG6U+m9R7C9E8Mk6CSHgSrBmBD5ZWH3x/G59DCySe5wUM6iMffPDnakY8TUoAwqSnEsZ1aPvebYhGll/lPeC3yxuw27HTYhXDNo3Wum05iag= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=R0toFVQV; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="R0toFVQV" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 050A61F00898; Thu, 17 Sep 2026 15:37:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789659472; bh=dlSFd8oW4zMHYlrhpAOgtjGd/csCg1JyBkS/rzNFPzo=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=R0toFVQVeCM00/Y3/NJ3Af+zAMYjMuTCO0gzQTlgA1nHrpX2suBIvbXbWWArevf/r 8eoKpDQWuNgyvzGIKFwdXgmj40M/f2EAFH/YMVvpf4R4PQwSXUO7iNOO7PjuHB4pui nxK54W3iktXprT6Jb0gp/xYNtffH/YCLb0QpXrAc= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Vincent Donnefort , Steven Rostedt , Sasha Levin Subject: [PATCH 7.2 268/733] ring-buffer: Remove ring_buffer_per_cpu::mapped Date: Thu, 17 Sep 2026 16:09:36 +0100 Message-ID: <20260917151358.017819891@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260917151350.597953846@linuxfoundation.org> References: <20260917151350.597953846@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 7.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Vincent Donnefort [ Upstream commit 8b502bf6eb3da15f4b954ad3632335ff10ed746a ] 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 Stable-dep-of: dae8dda341d2 ("tracing: Fix subbuf resize races with trace_pipe_raw readers") Signed-off-by: Sasha Levin --- 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 70e43fe3a1006..86e4c224071b3 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 */ @@ -632,6 +631,11 @@ 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; @@ -2567,7 +2571,6 @@ 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) @@ -6661,12 +6664,11 @@ 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; } } @@ -6915,8 +6917,8 @@ 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 */ @@ -7128,7 +7130,6 @@ 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; @@ -7167,8 +7168,6 @@ 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 @@ -7178,7 +7177,7 @@ 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; @@ -7620,11 +7619,7 @@ 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)) @@ -7633,13 +7628,10 @@ 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); @@ -7811,7 +7803,6 @@ 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 { @@ -7868,8 +7859,6 @@ 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