From mboxrd@z Thu Jan 1 00:00:00 1970 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 D53E122A4CC; Wed, 11 Jun 2025 08:03:49 +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=1749629030; cv=none; b=BI9fW7JDhM2N5NGQpekC4olRsnlBQnbH+c+kbAYR1+awU7dtvPucS+G6kyujOgUQCCq5UvhSyjxFKWDqFqF47LQ5C+DD2/pZDdh9DDvtJv/33v3kup3oIuYnpEC/zjVzYPNDUG//YfGIQPwVzPxFEjGPty6mcdLt26LJmBo4yqg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749629030; c=relaxed/simple; bh=FF/lHwVmvuS/PuJN9WCo9t19979ouT1jzg36Num1n2M=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=P5LSgIKA79pNFarB4G2+mp3KZcCwDJiD82g3uEnx9F1uulUCQl8cnMIJ1vpli2t8QRieHoNqrcXf92MWefQNESXwvVVqKoTT4iEEVeYIEk32XNXt1fwq/KwvZX0OCDdL3fVbqDt1Tfrc5XwhZ18qXGzLp06FKhg7Wg+27DOC1zQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=cso6HS8+; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="cso6HS8+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0F79DC4CEEE; Wed, 11 Jun 2025 08:03:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1749629029; bh=FF/lHwVmvuS/PuJN9WCo9t19979ouT1jzg36Num1n2M=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=cso6HS8+Kj0pZHq2A+5pz9++Z1mH/FyxlcippYbqh/sZqbS+1kGDK8RF+WB1sWj49 VsMkb4+ymBClrOPiAJaDlohazXJAgZiPS8bpqcfkd29rcF/S3yXCc4ISbPNQ4/Cw4w Yr+qv5IOx3D9iYJW4HTmcioSLsUV8uM3CFGle7tOo0zJRQRgm9ilvE70hF2Qd8P7LJ Xeh7pW4k+96KyAQXJttgc0mqx2fqVzC3XjSCrqD+BJOi3ShINLAabRdEEnf83nTbAc /p+/3oeGHI6JYS+byl+BJRwxhDKCD7rmIb8wZ8B77wC/Kq8Zi4sfG0myZVgXHBd3MN 5+YnylS1VTG4A== Date: Wed, 11 Jun 2025 17:03:46 +0900 From: Masami Hiramatsu (Google) To: Jason Xing Cc: axboe@kernel.dk, rostedt@goodmis.org, mathieu.desnoyers@efficios.com, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, linux-trace-kernel@vger.kernel.org, Jason Xing , Yushan Zhou Subject: Re: [PATCH v4 1/5] relayfs: abolish prev_padding Message-Id: <20250611170346.cc5b885bca560417602540c4@kernel.org> In-Reply-To: <20250610004844.66688-2-kerneljasonxing@gmail.com> References: <20250610004844.66688-1-kerneljasonxing@gmail.com> <20250610004844.66688-2-kerneljasonxing@gmail.com> X-Mailer: Sylpheed 3.8.0beta1 (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-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Tue, 10 Jun 2025 08:48:40 +0800 Jason Xing wrote: > From: Jason Xing > > prev_padding represents the unused space of certain subbuffer. If the > content of a call of relay_write() exceeds the limit of the remainder of > this subbuffer, it will skip storing in the rest space and record the > start point as buf->prev_padding in relay_switch_subbuf(). Since the buf > is a per-cpu big buffer, the point of prev_padding as a global value for > the whole buffer instead of a single subbuffer (whose padding info is > stored in buf->padding[]) seems meaningless from the real use cases, so > we don't bother to record it any more. Sounds reasonable. > > Reviewed-by: Yushan Zhou > Signed-off-by: Jason Xing Looks good to me. Reviewed-by: Masami Hiramatsu (Google) Thanks, > --- > drivers/gpu/drm/i915/gt/uc/intel_guc_log.c | 3 +-- > drivers/net/wwan/iosm/iosm_ipc_trace.c | 3 +-- > drivers/net/wwan/t7xx/t7xx_port_trace.c | 2 +- > include/linux/relay.h | 5 +---- > kernel/relay.c | 14 ++++++++------ > kernel/trace/blktrace.c | 2 +- > 6 files changed, 13 insertions(+), 16 deletions(-) > > diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_log.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_log.c > index e8a04e476c57..09a64f224c49 100644 > --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_log.c > +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_log.c > @@ -220,8 +220,7 @@ static int guc_action_control_log(struct intel_guc *guc, bool enable, > */ > static int subbuf_start_callback(struct rchan_buf *buf, > void *subbuf, > - void *prev_subbuf, > - size_t prev_padding) > + void *prev_subbuf) > { > /* > * Use no-overwrite mode by default, where relay will stop accepting > diff --git a/drivers/net/wwan/iosm/iosm_ipc_trace.c b/drivers/net/wwan/iosm/iosm_ipc_trace.c > index eeecfa3d10c5..9656254c1c6c 100644 > --- a/drivers/net/wwan/iosm/iosm_ipc_trace.c > +++ b/drivers/net/wwan/iosm/iosm_ipc_trace.c > @@ -51,8 +51,7 @@ static int ipc_trace_remove_buf_file_handler(struct dentry *dentry) > } > > static int ipc_trace_subbuf_start_handler(struct rchan_buf *buf, void *subbuf, > - void *prev_subbuf, > - size_t prev_padding) > + void *prev_subbuf) > { > if (relay_buf_full(buf)) { > pr_err_ratelimited("Relay_buf full dropping traces"); > diff --git a/drivers/net/wwan/t7xx/t7xx_port_trace.c b/drivers/net/wwan/t7xx/t7xx_port_trace.c > index 4ed8b4e29bf1..f16d3b01302c 100644 > --- a/drivers/net/wwan/t7xx/t7xx_port_trace.c > +++ b/drivers/net/wwan/t7xx/t7xx_port_trace.c > @@ -33,7 +33,7 @@ static int t7xx_trace_remove_buf_file_handler(struct dentry *dentry) > } > > static int t7xx_trace_subbuf_start_handler(struct rchan_buf *buf, void *subbuf, > - void *prev_subbuf, size_t prev_padding) > + void *prev_subbuf) > { > if (relay_buf_full(buf)) { > pr_err_ratelimited("Relay_buf full dropping traces"); > diff --git a/include/linux/relay.h b/include/linux/relay.h > index b3224111d074..e10a0fdf4325 100644 > --- a/include/linux/relay.h > +++ b/include/linux/relay.h > @@ -47,7 +47,6 @@ struct rchan_buf > unsigned int page_count; /* number of current buffer pages */ > unsigned int finalized; /* buffer has been finalized */ > size_t *padding; /* padding counts per sub-buffer */ > - size_t prev_padding; /* temporary variable */ > size_t bytes_consumed; /* bytes consumed in cur read subbuf */ > size_t early_bytes; /* bytes consumed before VFS inited */ > unsigned int cpu; /* this buf's cpu */ > @@ -84,7 +83,6 @@ struct rchan_callbacks > * @buf: the channel buffer containing the new sub-buffer > * @subbuf: the start of the new sub-buffer > * @prev_subbuf: the start of the previous sub-buffer > - * @prev_padding: unused space at the end of previous sub-buffer > * > * The client should return 1 to continue logging, 0 to stop > * logging. > @@ -100,8 +98,7 @@ struct rchan_callbacks > */ > int (*subbuf_start) (struct rchan_buf *buf, > void *subbuf, > - void *prev_subbuf, > - size_t prev_padding); > + void *prev_subbuf); > > /* > * create_buf_file - create file to represent a relay channel buffer > diff --git a/kernel/relay.c b/kernel/relay.c > index c0c93a04d4ce..94f79f52d826 100644 > --- a/kernel/relay.c > +++ b/kernel/relay.c > @@ -250,13 +250,13 @@ EXPORT_SYMBOL_GPL(relay_buf_full); > */ > > static int relay_subbuf_start(struct rchan_buf *buf, void *subbuf, > - void *prev_subbuf, size_t prev_padding) > + void *prev_subbuf) > { > if (!buf->chan->cb->subbuf_start) > return !relay_buf_full(buf); > > return buf->chan->cb->subbuf_start(buf, subbuf, > - prev_subbuf, prev_padding); > + prev_subbuf); > } > > /** > @@ -302,7 +302,7 @@ static void __relay_reset(struct rchan_buf *buf, unsigned int init) > for (i = 0; i < buf->chan->n_subbufs; i++) > buf->padding[i] = 0; > > - relay_subbuf_start(buf, buf->data, NULL, 0); > + relay_subbuf_start(buf, buf->data, NULL); > } > > /** > @@ -555,9 +555,11 @@ size_t relay_switch_subbuf(struct rchan_buf *buf, size_t length) > goto toobig; > > if (buf->offset != buf->chan->subbuf_size + 1) { > - buf->prev_padding = buf->chan->subbuf_size - buf->offset; > + size_t prev_padding; > + > + prev_padding = buf->chan->subbuf_size - buf->offset; > old_subbuf = buf->subbufs_produced % buf->chan->n_subbufs; > - buf->padding[old_subbuf] = buf->prev_padding; > + buf->padding[old_subbuf] = prev_padding; > buf->subbufs_produced++; > if (buf->dentry) > d_inode(buf->dentry)->i_size += > @@ -582,7 +584,7 @@ size_t relay_switch_subbuf(struct rchan_buf *buf, size_t length) > new_subbuf = buf->subbufs_produced % buf->chan->n_subbufs; > new = buf->start + new_subbuf * buf->chan->subbuf_size; > buf->offset = 0; > - if (!relay_subbuf_start(buf, new, old, buf->prev_padding)) { > + if (!relay_subbuf_start(buf, new, old)) { > buf->offset = buf->chan->subbuf_size + 1; > return 0; > } > diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c > index 3f6a7bdc6edf..d3083c88474e 100644 > --- a/kernel/trace/blktrace.c > +++ b/kernel/trace/blktrace.c > @@ -461,7 +461,7 @@ static const struct file_operations blk_msg_fops = { > * the user space app in telling how many lost events there were. > */ > static int blk_subbuf_start_callback(struct rchan_buf *buf, void *subbuf, > - void *prev_subbuf, size_t prev_padding) > + void *prev_subbuf) > { > struct blk_trace *bt; > > -- > 2.43.5 > -- Masami Hiramatsu (Google)