From nobody Fri Feb 13 16:38:51 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 CD93EAD31 for ; Thu, 23 May 2024 16:35:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716482157; cv=none; b=Fd+WZIKTxncAikG5G+0Y5RkmM8ySCrAptEquCyd7a9KXc649sgw/UF20NC/0whxTuKO9dNZ3tT9GBDv3GtD64l1cB3rStAjtYSFuD5oqXCLQXnXzEV5gxyFCg2t84GyGDCZXjMw4/q42xbZCDEBQ7JK7XHzb6Q9cLZtYpg6zdAw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716482157; c=relaxed/simple; bh=fCiXq2+boRzKiYqs6J/tR0g4gcJzzHcCC9A+1uj9Xh4=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type; b=tOHBl3hDohuOgR8Ioe8zvCqd4wCJCsTYdvualo2/vHDKg9FvTp/3LmH+Pk3ouzq26L9xb1IJq1EsZkOpGIaZmk4lsb5oNfrNC7GWMQ/vQmf+69GpNj0KeHTwzq2qWi5v74lKn/Jrht98+zi2v+7+rt30okHmIv3SDfOer6uXZoM= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6351CC2BD10; Thu, 23 May 2024 16:35:56 +0000 (UTC) Date: Thu, 23 May 2024 12:36:40 -0400 From: Steven Rostedt To: Linus Torvalds Cc: LKML , Masami Hiramatsu , Mathieu Desnoyers , Jeff Johnson , Petr Pavlu , Yang Li Subject: [GIT PULL] tracing: Small last minute fixes Message-ID: <20240523123640.0316a063@gandalf.local.home> X-Mailer: Claws Mail 3.20.0git84 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Linus, tracing: Minor last minute fixes - Fix a very tight race between the ring buffer readers and resizing the ring buffer. - Correct some stale comments in the ring buffer code. - Fix kernel-doc in the rv code. - Add a MODULE_DESCRIPTION to preemptirq_delay_test Please pull the latest trace-fixes-v6.10 tree, which can be found at: git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace.git trace-fixes-v6.10 Tag SHA1: 53ad9da2f490bc02e45f44bc2a33d4c3b6b78c6b Head SHA1: 1e8b7b3dbb3103d577a586ca72bc329f7b67120b Jeff Johnson (1): tracing: Add MODULE_DESCRIPTION() to preemptirq_delay_test Petr Pavlu (2): ring-buffer: Correct stale comments related to non-consuming readers ring-buffer: Fix a race between readers and resize checks Yang Li (1): rv: Update rv_en(dis)able_monitor doc to match kernel-doc ---- kernel/trace/preemptirq_delay_test.c | 1 + kernel/trace/ring_buffer.c | 25 ++++++++++++------------- kernel/trace/rv/rv.c | 2 ++ 3 files changed, 15 insertions(+), 13 deletions(-) --------------------------- diff --git a/kernel/trace/preemptirq_delay_test.c b/kernel/trace/preemptirq= _delay_test.c index 8c4ffd076162..cb0871fbdb07 100644 --- a/kernel/trace/preemptirq_delay_test.c +++ b/kernel/trace/preemptirq_delay_test.c @@ -215,4 +215,5 @@ static void __exit preemptirq_delay_exit(void) =20 module_init(preemptirq_delay_init) module_exit(preemptirq_delay_exit) +MODULE_DESCRIPTION("Preempt / IRQ disable delay thread to test latency tra= cers"); MODULE_LICENSE("GPL v2"); diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 7345a8b625fb..28853966aa9a 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -1460,6 +1460,11 @@ static void rb_check_bpage(struct ring_buffer_per_cp= u *cpu_buffer, * * As a safety measure we check to make sure the data pages have not * been corrupted. + * + * Callers of this function need to guarantee that the list of pages doesn= 't get + * modified during the check. In particular, if it's possible that the fun= ction + * is invoked with concurrent readers which can swap in a new reader page = then + * the caller should take cpu_buffer->reader_lock. */ static void rb_check_pages(struct ring_buffer_per_cpu *cpu_buffer) { @@ -2210,8 +2215,12 @@ int ring_buffer_resize(struct trace_buffer *buffer, = unsigned long size, */ synchronize_rcu(); for_each_buffer_cpu(buffer, cpu) { + unsigned long flags; + cpu_buffer =3D buffer->buffers[cpu]; + raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); rb_check_pages(cpu_buffer); + raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); } atomic_dec(&buffer->record_disabled); } @@ -5046,13 +5055,9 @@ EXPORT_SYMBOL_GPL(ring_buffer_consume); * @flags: gfp flags to use for memory allocation * * This performs the initial preparations necessary to iterate - * through the buffer. Memory is allocated, buffer recording + * through the buffer. Memory is allocated, buffer resizing * is disabled, and the iterator pointer is returned to the caller. * - * Disabling buffer recording prevents the reading from being - * corrupted. This is not a consuming read, so a producer is not - * expected. - * * After a sequence of ring_buffer_read_prepare calls, the user is * expected to make at least one call to ring_buffer_read_prepare_sync. * Afterwards, ring_buffer_read_start is invoked to get things going @@ -5139,8 +5144,7 @@ EXPORT_SYMBOL_GPL(ring_buffer_read_start); * ring_buffer_read_finish - finish reading the iterator of the buffer * @iter: The iterator retrieved by ring_buffer_start * - * This re-enables the recording to the buffer, and frees the - * iterator. + * This re-enables resizing of the buffer, and frees the iterator. */ void ring_buffer_read_finish(struct ring_buffer_iter *iter) @@ -5148,12 +5152,7 @@ ring_buffer_read_finish(struct ring_buffer_iter *ite= r) struct ring_buffer_per_cpu *cpu_buffer =3D iter->cpu_buffer; unsigned long flags; =20 - /* - * Ring buffer is disabled from recording, here's a good place - * to check the integrity of the ring buffer. - * Must prevent readers from trying to read, as the check - * clears the HEAD page and readers require it. - */ + /* Use this opportunity to check the integrity of the ring buffer. */ raw_spin_lock_irqsave(&cpu_buffer->reader_lock, flags); rb_check_pages(cpu_buffer); raw_spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); diff --git a/kernel/trace/rv/rv.c b/kernel/trace/rv/rv.c index 2f68e93fff0b..df0745a42a3f 100644 --- a/kernel/trace/rv/rv.c +++ b/kernel/trace/rv/rv.c @@ -245,6 +245,7 @@ static int __rv_disable_monitor(struct rv_monitor_def *= mdef, bool sync) =20 /** * rv_disable_monitor - disable a given runtime monitor + * @mdef: Pointer to the monitor definition structure. * * Returns 0 on success. */ @@ -256,6 +257,7 @@ int rv_disable_monitor(struct rv_monitor_def *mdef) =20 /** * rv_enable_monitor - enable a given runtime monitor + * @mdef: Pointer to the monitor definition structure. * * Returns 0 on success, error otherwise. */