blktrace: fix output of BLK_TC_PC events

BLK_TC_PC events should be treated differently with BLK_TC_FS events.

Before this patch:

 # echo 1 > /sys/block/sda/sda1/trace/enable
 # echo pc > /sys/block/sda/sda1/trace/act_mask
 # echo blk > /debugfs/tracing/current_tracer
 # (generate some BLK_TC_PC events)
 # cat trace
        bash-2184  [000]  1774.275413:   8,7    I   N [bash]
        bash-2184  [000]  1774.275435:   8,7    D   N [bash]
        bash-2184  [000]  1774.275540:   8,7    I   R [bash]
        bash-2184  [000]  1774.275547:   8,7    D   R [bash]
 ksoftirqd/0-4     [000]  1774.275580:   8,7    C   N 0 [0]
        bash-2184  [000]  1774.275648:   8,7    I   R [bash]
        bash-2184  [000]  1774.275653:   8,7    D   R [bash]
 ksoftirqd/0-4     [000]  1774.275682:   8,7    C   N 0 [0]
        bash-2184  [000]  1774.275739:   8,7    I   R [bash]
        bash-2184  [000]  1774.275744:   8,7    D   R [bash]
 ksoftirqd/0-4     [000]  1774.275771:   8,7    C   N 0 [0]
        bash-2184  [000]  1774.275804:   8,7    I   R [bash]
        bash-2184  [000]  1774.275808:   8,7    D   R [bash]
 ksoftirqd/0-4     [000]  1774.275836:   8,7    C   N 0 [0]

After this patch:

 # cat trace
        bash-2263  [000]   366.782149:   8,7    I   N 0 (00 ..) [bash]
        bash-2263  [000]   366.782323:   8,7    D   N 0 (00 ..) [bash]
        bash-2263  [000]   366.782557:   8,7    I   R 8 (25 00 ..) [bash]
        bash-2263  [000]   366.782560:   8,7    D   R 8 (25 00 ..) [bash]
 ksoftirqd/0-4     [000]   366.782582:   8,7    C   N (25 00 ..) [0]
        bash-2263  [000]   366.782648:   8,7    I   R 8 (5a 00 3f 00) [bash]
        bash-2263  [000]   366.782650:   8,7    D   R 8 (5a 00 3f 00) [bash]
 ksoftirqd/0-4     [000]   366.782669:   8,7    C   N (5a 00 3f 00) [0]
        bash-2263  [000]   366.782710:   8,7    I   R 8 (5a 00 08 00) [bash]
        bash-2263  [000]   366.782713:   8,7    D   R 8 (5a 00 08 00) [bash]
 ksoftirqd/0-4     [000]   366.782730:   8,7    C   N (5a 00 08 00) [0]
        bash-2263  [000]   366.783375:   8,7    I   R 36 (5a 00 08 00) [bash]
        bash-2263  [000]   366.783379:   8,7    D   R 36 (5a 00 08 00) [bash]
 ksoftirqd/0-4     [000]   366.783404:   8,7    C   N (5a 00 08 00) [0]

This is what we do with PC events in user-space blktrace.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <49D32387.9040106@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 80 insertions, 8 deletions

diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index e45e1af13563..2b98195b338b 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -971,6 +971,16 @@ static inline const void *pdu_start(const struct trace_entry *ent)
         return te_blk_io_trace(ent) + 1;
 }
 
+static inline u32 t_action(const struct trace_entry *ent)
+{
+        return te_blk_io_trace(ent)->action;
+}
+
+static inline u32 t_bytes(const struct trace_entry *ent)
+{
+        return te_blk_io_trace(ent)->bytes;
+}
+
 static inline u32 t_sec(const struct trace_entry *ent)
 {
         return te_blk_io_trace(ent)->bytes >> 9;
@@ -1031,25 +1041,87 @@ static int blk_log_action(struct trace_iterator *iter, const char *act)
                                 MAJOR(t->device), MINOR(t->device), act, rwbs);
 }
 
+static int blk_log_dump_pdu(struct trace_seq *s, const struct trace_entry *ent)
+{
+        const char *pdu_buf;
+        int pdu_len;
+        int i, end, ret;
+
+        pdu_buf = pdu_start(ent);
+        pdu_len = te_blk_io_trace(ent)->pdu_len;
+
+        if (!pdu_len)
+                return 1;
+
+        /* find the last zero that needs to be printed */
+        for (end = pdu_len - 1; end >= 0; end--)
+                if (pdu_buf[end])
+                        break;
+        end++;
+
+        if (!trace_seq_putc(s, '('))
+                return 0;
+
+        for (i = 0; i < pdu_len; i++) {
+
+                ret = trace_seq_printf(s, "%s%02x",
+                                       i == 0 ? "" : " ", pdu_buf[i]);
+                if (!ret)
+                        return ret;
+
+                /*
+                 * stop when the rest is just zeroes and indicate so
+                 * with a ".." appended
+                 */
+                if (i == end && end != pdu_len - 1)
+                        return trace_seq_puts(s, " ..) ");
+        }
+
+        return trace_seq_puts(s, ") ");
+}
+
 static int blk_log_generic(struct trace_seq *s, const struct trace_entry *ent)
 {
         char cmd[TASK_COMM_LEN];
 
         trace_find_cmdline(ent->pid, cmd);
 
-        if (t_sec(ent))
-                return trace_seq_printf(s, "%llu + %u [%s]\n",
-                                        t_sector(ent), t_sec(ent), cmd);
-        return trace_seq_printf(s, "[%s]\n", cmd);
+        if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
+                int ret;
+
+                ret = trace_seq_printf(s, "%u ", t_bytes(ent));
+                if (!ret)
+                        return 0;
+                ret = blk_log_dump_pdu(s, ent);
+                if (!ret)
+                        return 0;
+                return trace_seq_printf(s, "[%s]\n", cmd);
+        } else {
+                if (t_sec(ent))
+                        return trace_seq_printf(s, "%llu + %u [%s]\n",
+                                                t_sector(ent), t_sec(ent), cmd);
+                return trace_seq_printf(s, "[%s]\n", cmd);
+        }
 }
 
 static int blk_log_with_error(struct trace_seq *s,
                               const struct trace_entry *ent)
 {
-        if (t_sec(ent))
-                return trace_seq_printf(s, "%llu + %u [%d]\n", t_sector(ent),
-                                        t_sec(ent), t_error(ent));
-        return trace_seq_printf(s, "%llu [%d]\n", t_sector(ent), t_error(ent));
+        if (t_action(ent) & BLK_TC_ACT(BLK_TC_PC)) {
+                int ret;
+
+                ret = blk_log_dump_pdu(s, ent);
+                if (ret)
+                        return trace_seq_printf(s, "[%d]\n", t_error(ent));
+                return 0;
+        } else {
+                if (t_sec(ent))
+                        return trace_seq_printf(s, "%llu + %u [%d]\n",
+                                                t_sector(ent),
+                                                t_sec(ent), t_error(ent));
+                return trace_seq_printf(s, "%llu [%d]\n",
+                                        t_sector(ent), t_error(ent));
+        }
 }
 
 static int blk_log_remap(struct trace_seq *s, const struct trace_entry *ent)