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Wed, 11 Jun 2025 23:12:11 -0700 (PDT) From: Jason Xing To: axboe@kernel.dk, rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, akpm@linux-foundation.org Cc: linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, linux-trace-kernel@vger.kernel.org, Jason Xing , Yushan Zhou Subject: [PATCH v5 1/5] relayfs: abolish prev_padding Date: Thu, 12 Jun 2025 14:11:57 +0800 Message-Id: <20250612061201.34272-2-kerneljasonxing@gmail.com> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20250612061201.34272-1-kerneljasonxing@gmail.com> References: <20250612061201.34272-1-kerneljasonxing@gmail.com> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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. Reviewed-by: Yushan Zhou Reviewed-by: Masami Hiramatsu (Google) Signed-off-by: Jason Xing --- 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