tracing/core: bring back raw trace_printk for dynamic formats strings

Impact: fix callsites with dynamic format strings

Since its new binary implementation, trace_printk() internally uses static
containers for the format strings on each callsites. But the value is
assigned once at build time, which means that it can't take dynamic
formats.

So this patch unearthes the raw trace_printk implementation for the callers
that will need trace_printk to be able to carry these dynamic format
strings. The trace_printk() macro will use the appropriate implementation
for each callsite. Most of the time however, the binary implementation will
still be used.

The other impact of this patch is that mmiotrace_printk() will use the old
implementation because it calls the low level trace_vprintk and we can't
guess here whether the format passed in it is dynamic or not.

Some parts of this patch have been written by Steven Rostedt (most notably
the part that chooses the appropriate implementation for each callsites).

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>

1 files changed, 2 insertions, 5 deletions

diff --git a/kernel/trace/trace_mmiotrace.c b/kernel/trace/trace_mmiotrace.c
index 23e346a734c..f095916e477 100644
--- a/kernel/trace/trace_mmiotrace.c
+++ b/kernel/trace/trace_mmiotrace.c
@@ -254,6 +254,7 @@ static enum print_line_t mmio_print_mark(struct trace_iterator *iter)
 {
         struct trace_entry *entry = iter->ent;
         struct print_entry *print = (struct print_entry *)entry;
+        const char *msg         = print->buf;
         struct trace_seq *s     = &iter->seq;
         unsigned long long t    = ns2usecs(iter->ts);
         unsigned long usec_rem  = do_div(t, USEC_PER_SEC);
@@ -261,11 +262,7 @@ static enum print_line_t mmio_print_mark(struct trace_iterator *iter)
         int ret;
 
         /* The trailing newline must be in the message. */
-        ret = trace_seq_printf(s, "MARK %u.%06lu ", secs, usec_rem);
-        if (!ret)
-                return TRACE_TYPE_PARTIAL_LINE;
-
-        ret = trace_seq_bprintf(s, print->fmt, print->buf);
+        ret = trace_seq_printf(s, "MARK %u.%06lu %s", secs, usec_rem, msg);
         if (!ret)
                 return TRACE_TYPE_PARTIAL_LINE;