linux-kernel - [PATCH v3 01/16] blktrace: only calculate trace length once

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20251015105435.527088-2-johannes.thumshirn@wdc.com>
Date: Wed, 15 Oct 2025 12:54:20 +0200
From: Johannes Thumshirn <johannes.thumshirn@....com>
To: axboe@...nel.dk
Cc: chaitanyak@...dia.com,
	dlemoal@...nel.org,
	hare@...e.de,
	hch@....de,
	john.g.garry@...cle.com,
	linux-block@...r.kernel.org,
	linux-btrace@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-trace-kernel@...r.kernel.org,
	martin.petersen@...cle.com,
	mathieu.desnoyers@...icios.com,
	mhiramat@...nel.org,
	naohiro.aota@....com,
	rostedt@...dmis.org,
	shinichiro.kawasaki@....com,
	Johannes Thumshirn <johannes.thumshirn@....com>
Subject: [PATCH v3 01/16] blktrace: only calculate trace length once

De-duplicate the calculation of the trace length instead of doing the
calculation twice, once for calling trace_buffer_lock_reserve() and once
for calling relay_reserve().

Reviewed-by: Christoph Hellwig <hch@....de>
Reviewed-by: Damien Le Moal <dlemoal@...nel.org>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@....com>
---
 kernel/trace/blktrace.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index 6941145b5058..bc4b885f2cec 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -76,13 +76,14 @@ static void trace_note(struct blk_trace *bt, pid_t pid, int action,
 	int cpu = smp_processor_id();
 	bool blk_tracer = blk_tracer_enabled;
 	ssize_t cgid_len = cgid ? sizeof(cgid) : 0;
+	size_t trace_len;
 
+	trace_len = sizeof(*t) + cgid_len + len;
 	if (blk_tracer) {
 		buffer = blk_tr->array_buffer.buffer;
 		trace_ctx = tracing_gen_ctx_flags(0);
 		event = trace_buffer_lock_reserve(buffer, TRACE_BLK,
-						  sizeof(*t) + len + cgid_len,
-						  trace_ctx);
+						  trace_len, trace_ctx);
 		if (!event)
 			return;
 		t = ring_buffer_event_data(event);
@@ -92,7 +93,7 @@ static void trace_note(struct blk_trace *bt, pid_t pid, int action,
 	if (!bt->rchan)
 		return;
 
-	t = relay_reserve(bt->rchan, sizeof(*t) + len + cgid_len);
+	t = relay_reserve(bt->rchan, trace_len);
 	if (t) {
 		t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
 		t->time = ktime_to_ns(ktime_get());
@@ -228,6 +229,7 @@ static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
 	bool blk_tracer = blk_tracer_enabled;
 	ssize_t cgid_len = cgid ? sizeof(cgid) : 0;
 	const enum req_op op = opf & REQ_OP_MASK;
+	size_t trace_len;
 
 	if (unlikely(bt->trace_state != Blktrace_running && !blk_tracer))
 		return;
@@ -250,14 +252,14 @@ static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
 		return;
 	cpu = raw_smp_processor_id();
 
+	trace_len = sizeof(*t) + pdu_len + cgid_len;
 	if (blk_tracer) {
 		tracing_record_cmdline(current);
 
 		buffer = blk_tr->array_buffer.buffer;
 		trace_ctx = tracing_gen_ctx_flags(0);
 		event = trace_buffer_lock_reserve(buffer, TRACE_BLK,
-						  sizeof(*t) + pdu_len + cgid_len,
-						  trace_ctx);
+						  trace_len, trace_ctx);
 		if (!event)
 			return;
 		t = ring_buffer_event_data(event);
@@ -273,7 +275,7 @@ static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
 	 * from coming in and stepping on our toes.
 	 */
 	local_irq_save(flags);
-	t = relay_reserve(bt->rchan, sizeof(*t) + pdu_len + cgid_len);
+	t = relay_reserve(bt->rchan, trace_len);
 	if (t) {
 		sequence = per_cpu_ptr(bt->sequence, cpu);
 
-- 
2.51.0