tracing: printk:console fix and __get_str() cleanup

This patch series fixes a problem on printk:console tracepoint that prints a blank line in the trace output after each printk message that finishes with '\n'.

It also does some cleanup on __get_str() usage, that was found while fixing the printk:console tracepoint.

Daniel Bristot de Oliveira (4):
tracing: Use outer () on __get_str() definition tracing, RAS: Cleanup on __get_str() usage
tracing: Use __get_str() when manipulating strings printk, tracing: Avoiding unneeded blank lines

 fs/nfs/nfs4trace.h            |  4 ++--
 fs/nfs/nfstrace.h             |  4 ++--
 include/ras/ras_event.h       |  4 ++--
 include/trace/events/printk.h | 12 ++++++++++--
 include/trace/perf.h          |  2 +-
 include/trace/trace_events.h  |  2 +-
 6 files changed, 18 insertions(+), 10 deletions(-)

2.7.4

__get_str(str)'s definition includes a (char *) operator overloading that is not protected with outer ().

This patch adds () around __get_str()'s definition, enabling some code cleanup.

---
 include/trace/perf.h         | 2 +-
 include/trace/trace_events.h | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

index 26486fc..7144550 100644
@@ -15,7 +15,7 @@
 		((__entry->__data_loc_##field >> 16) & 0xffff)
 
 #undef __get_str
-#define __get_str(field) (char *)__get_dynamic_array(field)
+#define __get_str(field) ((char *)__get_dynamic_array(field))
 
 #undef __get_bitmask
 #define __get_bitmask(field) (char *)__get_dynamic_array(field)

index 170c93b..427e4aa 100644
@@ -256,7 +256,7 @@ TRACE_MAKE_SYSTEM_STR();
 		((__entry->__data_loc_##field >> 16) & 0xffff)
 
 #undef __get_str
-#define __get_str(field) (char *)__get_dynamic_array(field)
+#define __get_str(field) ((char *)__get_dynamic_array(field))
 
 #undef __get_bitmask
 #define __get_bitmask(field)						\

2.7.4

__get_str(msg) does not need (char *) operator overloading to access mgs's elements anymore. This patch substitutes
((char *)__get_str(msg))[0] usage to __get_str(msg)[0].

It is just a code cleanup, no changes on tracepoint ABI.

---
 include/ras/ras_event.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

index 1443d79..1791a12 100644
@@ -147,7 +147,7 @@ TRACE_EVENT(mc_event,
 		  __entry->error_count,
 		  mc_event_error_type(__entry->error_type),
 		  __entry->error_count > 1 ? "s" : "",
-		  ((char *)__get_str(msg))[0] ? " " : "",
+		  __get_str(msg)[0] ? " " : "",
 		  __get_str(msg),
 		  __get_str(label),
 		  __entry->mc_index,

@@ -157,7 +157,7 @@ TRACE_EVENT(mc_event,
 		  __entry->address,
 		  1 << __entry->grain_bits,
 		  __entry->syndrome,
-		  ((char *)__get_str(driver_detail))[0] ? " " : "",
+		  __get_str(driver_detail)[0] ? " " : "",
 		  __get_str(driver_detail))
 );
 

2.7.4

Use __get_str(str) rather than __get_dynamic_array(str) when deadling with strings.

It is just a code cleanup, no changes on tracepoint ABI.

---
 fs/nfs/nfs4trace.h            | 4 ++--
 fs/nfs/nfstrace.h             | 4 ++--
 include/trace/events/printk.h | 4 ++--
 3 files changed, 6 insertions(+), 6 deletions(-)

index 2c8d05d..adec59a 100644
@@ -1235,8 +1235,8 @@ DECLARE_EVENT_CLASS(nfs4_idmap_event,
 				len = 0;
 			__entry->error = error < 0 ? error : 0;
 			__entry->id = id;
-			memcpy(__get_dynamic_array(name), name, len);
-			((char *)__get_dynamic_array(name))[len] = 0;
+			memcpy(__get_str(name), name, len);
+			__get_str(name)[len] = 0;
 		),
 
 		TP_printk(

index 9f80a08..32ff934 100644
@@ -707,9 +707,9 @@ TRACE_EVENT(nfs_sillyrename_unlink,
 			__entry->dev = dir->i_sb->s_dev;
 			__entry->dir = NFS_FILEID(dir);
 			__entry->error = error;
-			memcpy(__get_dynamic_array(name),
+			memcpy(__get_str(name),
 				data->args.name.name, len);
-			((char *)__get_dynamic_array(name))[len] = 0;
+			__get_str(name)[len] = 0;
 		),
 
 		TP_printk(

index c008bc9..542a755 100644
@@ -16,8 +16,8 @@ TRACE_EVENT(console,
 	),
 
 	TP_fast_assign(
-		memcpy(__get_dynamic_array(msg), text, len);
-		((char *)__get_dynamic_array(msg))[len] = 0;
+		memcpy(__get_str(msg), text, len);
+		__get_str(msg)[len] = 0;
 	),
 
 	TP_printk("%s", __get_str(msg))

2.7.4

Printk messages often finish with '\n' to cause a new line. But as each tracepoint is already printed in a new line, printk messages that finish with '\n' ends up adding a blank line to the trace output. For example:

     kworker/0:1-86    [000] d...    46.006949: console: [   46.006946] usb 1-3: USB disconnect, device number 3

     kworker/2:2-374   [002] d...    48.699342: console: [   48.699339] usb 1-3: new high-speed USB device number 4 using ehci-pci

     kworker/2:2-374   [002] d...    49.041450: console: [   49.041448] usb 1-3: New USB device found, idVendor=5986, idProduct=0

To avoid unneeded blank lines, this patch checks if the printk message finishes with '\n', if so, it cut is off the '\n' to avoid blank lines.

In a patched kernel, the same messages are printed without extra blank lines. For example:

     kworker/0:4-185   [000] d...    23.641738: console: [   23.641736] usb 1-3: USB disconnect, device number 3
     kworker/0:4-185   [000] d...    24.918703: console: [   24.918700] usb 1-3: new high-speed USB device number 4 using ehci-pci
     kworker/0:4-185   [000] d...    25.228308: console: [   25.228306] usb 1-3: New USB device found, idVendor=5986, idProduct=02d5

---
 include/trace/events/printk.h | 8 ++++++++
 1 file changed, 8 insertions(+)

index 542a755..bc9139d29 100644
@@ -16,6 +16,14 @@ TRACE_EVENT(console,
 	),
 
 	TP_fast_assign(
+		/*
+		 * Each trace entry is printed in a new line.
+		 * If the msg finishes with '\n', cut it off
+		 * to avoid blank lines in the trace.
+		 */
+		if ((len > 0) && (text[len-1] == '\n'))
+			len -= 1;
+
 		memcpy(__get_str(msg), text, len);
 		__get_str(msg)[len] = 0;
 	),

2.7.4

This is just a gentle ping.

Thanks in advance!

-- Daniel