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Petersen" , Johannes Thumshirn Subject: [PATCH v2 03/15] blktrace: split out relaying a blktrace event Date: Thu, 25 Sep 2025 17:02:19 +0200 Message-ID: <20250925150231.67342-4-johannes.thumshirn@wdc.com> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250925150231.67342-1-johannes.thumshirn@wdc.com> References: <20250925150231.67342-1-johannes.thumshirn@wdc.com> 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" Split out the code relaying a blktrace event to user-space using relayfs. This enables adding a second version supporting a new version of the protocol. Reviewed-by: Christoph Hellwig Signed-off-by: Johannes Thumshirn Reviewed-by: Damien Le Moal --- kernel/trace/blktrace.c | 60 ++++++++++++++++++++++------------------- 1 file changed, 32 insertions(+), 28 deletions(-) diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c index 25a0a1b09747..51745832c713 100644 --- a/kernel/trace/blktrace.c +++ b/kernel/trace/blktrace.c @@ -91,6 +91,26 @@ static void record_blktrace_event(struct blk_io_trace *t= , pid_t pid, int cpu, memcpy((void *)t + sizeof(*t) + cgid_len, pdu_data, pdu_len); } =20 +static void relay_blktrace_event(struct blk_trace *bt, unsigned long seque= nce, + pid_t pid, int cpu, sector_t sector, int bytes, + u32 what, int error, u64 cgid, + ssize_t cgid_len, void *pdu_data, int pdu_len) +{ + struct blk_io_trace *t; + size_t trace_len =3D sizeof(*t) + pdu_len + cgid_len; + + t =3D relay_reserve(bt->rchan, trace_len); + if (!t) + return; + + t->magic =3D BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION; + t->sequence =3D sequence; + t->time =3D ktime_to_ns(ktime_get()); + + record_blktrace_event(t, pid, cpu, sector, bytes, what, bt->dev, error, + cgid, cgid_len, pdu_data, pdu_len); +} + /* * Send out a notify message. */ @@ -126,16 +146,9 @@ static void trace_note(struct blk_trace *bt, pid_t pid= , int action, if (!bt->rchan) return; =20 - t =3D relay_reserve(bt->rchan, trace_len); - if (t) { - t->magic =3D BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION; - t->time =3D ktime_to_ns(ktime_get()); - - record_blktrace_event(t, pid, cpu, 0, 0, - action | (cgid ? __BLK_TN_CGROUP : 0), - bt->dev, 0, cgid, cgid_len, (void *)data, - len); - } + relay_blktrace_event(bt, 0, pid, cpu, 0, 0, + action | (cgid ? __BLK_TN_CGROUP : 0), 0, cgid, + cgid_len, (void *)data, len); } =20 /* @@ -246,7 +259,6 @@ static void __blk_add_trace(struct blk_trace *bt, secto= r_t sector, int bytes, struct task_struct *tsk =3D current; struct ring_buffer_event *event =3D NULL; struct trace_buffer *buffer =3D NULL; - struct blk_io_trace *t; unsigned long flags =3D 0; unsigned long *sequence; unsigned int trace_ctx =3D 0; @@ -278,20 +290,21 @@ static void __blk_add_trace(struct blk_trace *bt, sec= tor_t sector, int bytes, return; cpu =3D raw_smp_processor_id(); =20 - trace_len =3D sizeof(*t) + pdu_len + cgid_len; if (blk_tracer) { tracing_record_cmdline(current); =20 buffer =3D blk_tr->array_buffer.buffer; trace_ctx =3D tracing_gen_ctx_flags(0); + trace_len =3D sizeof(struct blk_io_trace) + pdu_len + cgid_len; event =3D trace_buffer_lock_reserve(buffer, TRACE_BLK, trace_len, trace_ctx); if (!event) return; - t =3D ring_buffer_event_data(event); =20 - record_blktrace_event(t, pid, cpu, sector, bytes, what, bt->dev, - error, cgid, cgid_len, pdu_data, pdu_len); + record_blktrace_event(ring_buffer_event_data(event), + pid, cpu, sector, bytes, what, bt->dev, + error, cgid, cgid_len, pdu_data, + pdu_len); =20 trace_buffer_unlock_commit(blk_tr, buffer, event, trace_ctx); return; @@ -306,19 +319,10 @@ static void __blk_add_trace(struct blk_trace *bt, sec= tor_t sector, int bytes, * from coming in and stepping on our toes. */ local_irq_save(flags); - t =3D relay_reserve(bt->rchan, trace_len); - if (t) { - sequence =3D per_cpu_ptr(bt->sequence, cpu); - - t->magic =3D BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION; - t->sequence =3D ++(*sequence); - t->time =3D ktime_to_ns(ktime_get()); - - record_blktrace_event(t, pid, cpu, sector, bytes, what, - bt->dev, error, cgid, cgid_len, - pdu_data, pdu_len); - } - + sequence =3D per_cpu_ptr(bt->sequence, cpu); + (*sequence)++; + relay_blktrace_event(bt, *sequence, pid, cpu, sector, bytes, what, + error, cgid, cgid_len, pdu_data, pdu_len); local_irq_restore(flags); } =20 --=20 2.51.0