diff mbox series

[lttng-ust] Improve tracef/tracelog to use the stack for small strings

Message ID 20210525134422.620425-1-nolange79@gmail.com
State New
Headers show
Series [lttng-ust] Improve tracef/tracelog to use the stack for small strings | expand

Commit Message

Norbert Lange May 25, 2021, 1:44 p.m. UTC
Support two common cases, one being that the resulting message is
small enough to fit into a on-stack buffer.
The seconds being the common 'printf("%s", "Message")' scheme.

Unfortunately, iterating a va_list is destructive,
so it has to be copied before calling vprintf.

The implementation was moved to a separate file,
used by both tracef.c and tracelog.c.

Signed-off-by: Norbert Lange <nolange79 at gmail.com>
---
 src/common/tracer.h                           |  2 +
 src/lib/lttng-ust-tracepoint/tracef.c         | 32 ++-----
 .../lttng-ust-tracepoint/tracelog-internal.h  | 83 +++++++++++++++++++
 src/lib/lttng-ust-tracepoint/tracelog.c       | 40 ++-------
 4 files changed, 102 insertions(+), 55 deletions(-)
 create mode 100644 src/lib/lttng-ust-tracepoint/tracelog-internal.h

Comments

Norbert Lange May 25, 2021, 1:47 p.m. UTC | #1
Am Di., 25. Mai 2021 um 15:44 Uhr schrieb Norbert Lange <nolange79 at gmail.com>:
>
> Support two common cases, one being that the resulting message is
> small enough to fit into a on-stack buffer.
> The seconds being the common 'printf("%s", "Message")' scheme.
>
> Unfortunately, iterating a va_list is destructive,
> so it has to be copied before calling vprintf.
>
> The implementation was moved to a separate file,
> used by both tracef.c and tracelog.c.
>
> Signed-off-by: Norbert Lange <nolange79 at gmail.com>
> ---
>  src/common/tracer.h                           |  2 +
>  src/lib/lttng-ust-tracepoint/tracef.c         | 32 ++-----
>  .../lttng-ust-tracepoint/tracelog-internal.h  | 83 +++++++++++++++++++
>  src/lib/lttng-ust-tracepoint/tracelog.c       | 40 ++-------
>  4 files changed, 102 insertions(+), 55 deletions(-)
>  create mode 100644 src/lib/lttng-ust-tracepoint/tracelog-internal.h
>
> diff --git a/src/common/tracer.h b/src/common/tracer.h
> index 2affd6ab..8e18c9b5 100644
> --- a/src/common/tracer.h
> +++ b/src/common/tracer.h
> @@ -26,6 +26,8 @@
>  #define LTTNG_RFLAG_EXTENDED           RING_BUFFER_RFLAG_END
>  #define LTTNG_RFLAG_END                        (LTTNG_RFLAG_EXTENDED << 1)
>
> +#define LTTNG_TRACE_PRINTF_BUFSIZE     512
> +
>  /*
>   * LTTng client type enumeration. Used by the consumer to map the
>   * callbacks from its own address space.
> diff --git a/src/lib/lttng-ust-tracepoint/tracef.c b/src/lib/lttng-ust-tracepoint/tracef.c
> index c05c7811..92911e1d 100644
> --- a/src/lib/lttng-ust-tracepoint/tracef.c
> +++ b/src/lib/lttng-ust-tracepoint/tracef.c
> @@ -7,6 +7,7 @@
>  #define _LGPL_SOURCE
>  #include <stdio.h>
>  #include "common/macros.h"
> +#include "common/tracer.h"
>
>  /* The tracepoint definition is public, but the provider definition is hidden. */
>  #define LTTNG_UST_TRACEPOINT_PROVIDER_HIDDEN_DEFINITION
> @@ -15,39 +16,22 @@
>  #define LTTNG_UST_TRACEPOINT_DEFINE
>  #include "lttng-ust-tracef-provider.h"
>
> -static inline
> -void lttng_ust___vtracef(const char *fmt, va_list ap)
> -       __attribute__((always_inline, format(printf, 1, 0)));
> -static inline
> -void lttng_ust___vtracef(const char *fmt, va_list ap)
> -{
> -       char *msg;
> -       const int len = vasprintf(&msg, fmt, ap);
> -
> -       /* len does not include the final \0 */
> -       if (len < 0)
> -               goto end;
> -       lttng_ust_tracepoint_cb_lttng_ust_tracef___event(msg, len,
> -               LTTNG_UST_CALLER_IP());
> -       free(msg);
> -end:
> -       return;
> -}
> +#include "tracelog-internal.h"
>
>  void lttng_ust__vtracef(const char *fmt, va_list ap)
>         __attribute__((format(printf, 1, 0)));
>  void lttng_ust__vtracef(const char *fmt, va_list ap)
>  {
> -       lttng_ust___vtracef(fmt, ap);
> +       LTTNG_UST_TRACELOG_VALIST(fmt, ap,
> +               lttng_ust_tracepoint_cb_lttng_ust_tracef___event,
> +               msg, len, LTTNG_UST_CALLER_IP());
>  }
>
>  void lttng_ust__tracef(const char *fmt, ...)
>         __attribute__((format(printf, 1, 2)));
>  void lttng_ust__tracef(const char *fmt, ...)
>  {
> -       va_list ap;
> -
> -       va_start(ap, fmt);
> -       lttng_ust___vtracef(fmt, ap);
> -       va_end(ap);
> +       LTTNG_UST_TRACELOG_VARARG(fmt,
> +               lttng_ust_tracepoint_cb_lttng_ust_tracef___event,
> +               msg, len, LTTNG_UST_CALLER_IP());
>  }
> diff --git a/src/lib/lttng-ust-tracepoint/tracelog-internal.h b/src/lib/lttng-ust-tracepoint/tracelog-internal.h
> new file mode 100644
> index 00000000..291ff27c
> --- /dev/null
> +++ b/src/lib/lttng-ust-tracepoint/tracelog-internal.h
> @@ -0,0 +1,83 @@
> +/*
> + * SPDX-License-Identifier: MIT
> + *
> + * Copyright (C) 2013-2014 Mathieu Desnoyers <mathieu.desnoyers at efficios.com>
> + * Copyright (C) 2021 Norbert Lange <nolange79 at gmail.com>
> + *
> + * Shared helper macro for tracelog and tracef
> + */
> +
> +#define LTTNG_UST_TRACELOG_VARARG(fmt, callback, ...) \
> +       va_list ap; \
> +       char local_buf[LTTNG_TRACE_PRINTF_BUFSIZE]; \
> +       int len; \
> +       char *msg = local_buf; \
> +       size_t buflen = sizeof(local_buf); \
> +       char *alloc_buff = NULL; \
> +\
> +       if (caa_unlikely(fmt[0] == '%' && fmt[1] == 's' && fmt[2] == '\0')) { \
> +               va_start(ap, fmt); \
> +               msg = va_arg(ap, char *); \
> +               va_end(ap); \
> +               len = strlen(msg); \
> +       } else \
> +               for(;;) { \
> +                       va_start(ap, fmt); \
> +                       len = vsnprintf(msg, buflen, fmt, ap); \
> +                       va_end(ap); \
> +\
> +                       if (caa_unlikely(len >= (int)sizeof(local_buf) && !alloc_buff)) { \
> +                               buflen = (size_t)len + 1U; \
> +                               len = -1; \
> +                               alloc_buff = (char *)malloc(buflen); \
> +                               msg = alloc_buff; \
> +                               if (!alloc_buff) \
> +                                       break; \
> +                       } else \
> +                               break; \
> +               } \
> +\
> +       /* len does not include the final \0 */ \
> +       if (caa_likely(len >= 0)) { \
> +               callback(__VA_ARGS__); \
> +       } \
> +       /* Dont call a potentially instrumented forbidden free needlessly. */ \
> +       if (caa_unlikely(alloc_buff)) \
> +               free(alloc_buff);
> +
> +#define LTTNG_UST_TRACELOG_VALIST(fmt, ap, callback, ...) \
> +       char local_buf[LTTNG_TRACE_PRINTF_BUFSIZE]; \
> +       int len; \
> +       char *msg = local_buf; \
> +       size_t buflen = sizeof(local_buf); \
> +       char *alloc_buff = NULL; \
> +\
> +       if (caa_unlikely(fmt[0] == '%' && fmt[1] == 's' && fmt[2] == '\0')) { \
> +               msg = va_arg(ap, char *); \
> +               len = strlen(msg); \
> +       } else \
> +               for(;;) { \
> +                       va_list ap2; \
> +\
> +                       va_copy(ap2, ap); \
> +                       len = vsnprintf(msg, buflen, fmt, ap2); \
> +                       va_end(ap2); \
> +\
> +                       if (caa_unlikely(len >= (int)sizeof(local_buf) && !alloc_buff)) { \
> +                               buflen = (size_t)len + 1U; \
> +                               len = -1; \
> +                               alloc_buff = (char *)malloc(buflen); \
> +                               msg = alloc_buff; \
> +                               if (!alloc_buff) \
> +                                       break; \
> +                       } else \
> +                               break; \
> +               } \
> +\
> +       /* len does not include the final \0 */ \
> +       if (caa_likely(len >= 0)) { \
> +               callback(__VA_ARGS__); \
> +       } \
> +       /* Dont call a potentially instrumented forbidden free needlessly. */ \
> +       if (caa_unlikely(alloc_buff)) \
> +               free(alloc_buff);
> diff --git a/src/lib/lttng-ust-tracepoint/tracelog.c b/src/lib/lttng-ust-tracepoint/tracelog.c
> index 8147d7a3..bd38032c 100644
> --- a/src/lib/lttng-ust-tracepoint/tracelog.c
> +++ b/src/lib/lttng-ust-tracepoint/tracelog.c
> @@ -7,6 +7,7 @@
>  #define _LGPL_SOURCE
>  #include <stdio.h>
>  #include "common/macros.h"
> +#include "common/tracer.h"
>
>  /* The tracepoint definition is public, but the provider definition is hidden. */
>  #define LTTNG_UST_TRACEPOINT_PROVIDER_HIDDEN_DEFINITION
> @@ -15,32 +16,9 @@
>  #define LTTNG_UST_TRACEPOINT_DEFINE
>  #include "lttng-ust-tracelog-provider.h"
>
> +#include "tracelog-internal.h"
> +
>  #define LTTNG_UST_TRACELOG_CB(level) \
> -       static inline \
> -       void lttng_ust___vtracelog_##level(const char *file, \
> -                       int line, const char *func, \
> -                       const char *fmt, va_list ap) \
> -               __attribute__((always_inline, format(printf, 4, 0))); \
> -       \
> -       static inline \
> -       void lttng_ust___vtracelog_##level(const char *file, \
> -                       int line, const char *func, \
> -                       const char *fmt, va_list ap) \
> -       { \
> -               char *msg; \
> -               const int len = vasprintf(&msg, fmt, ap); \
> -               \
> -               /* len does not include the final \0 */ \
> -               if (len < 0) \
> -                       goto end; \
> -               lttng_ust_tracepoint_cb_lttng_ust_tracelog___##level(file, \
> -                       line, func, msg, len, \
> -                       LTTNG_UST_CALLER_IP()); \
> -               free(msg); \
> -       end: \
> -               return; \
> -       } \
> -       \
>         void lttng_ust__vtracelog_##level(const char *file, \
>                         int line, const char *func, \
>                         const char *fmt, va_list ap) \
> @@ -53,7 +31,9 @@
>                         int line, const char *func, \
>                         const char *fmt, va_list ap) \
>         { \
> -               lttng_ust___vtracelog_##level(file, line, func, fmt, ap); \
> +               LTTNG_UST_TRACELOG_VALIST(fmt, ap, \
> +                       lttng_ust_tracepoint_cb_lttng_ust_tracelog___##level, \
> +                       file, line, func, msg, len, LTTNG_UST_CALLER_IP()); \
>         } \
>         \
>         void lttng_ust__tracelog_##level(const char *file, \
> @@ -68,11 +48,9 @@
>                         int line, const char *func, \
>                         const char *fmt, ...) \
>         { \
> -               va_list ap; \
> -               \
> -               va_start(ap, fmt); \
> -               lttng_ust___vtracelog_##level(file, line, func, fmt, ap); \
> -               va_end(ap); \
> +               LTTNG_UST_TRACELOG_VARARG(fmt, \
> +                       lttng_ust_tracepoint_cb_lttng_ust_tracelog___##level, \
> +                       file, line, func, msg, len, LTTNG_UST_CALLER_IP()); \
>         }
>
>  LTTNG_UST_TRACELOG_CB(LTTNG_UST_TRACEPOINT_LOGLEVEL_EMERG)
> --
> 2.30.2
>

This is to be applied on top of:
https://review.lttng.org/c/lttng-ust/+/5927 Move tracef/tracelog
symbols to liblttng-ust-tracepoint.so

So consider this a WIP for feedback.

Norbert
diff mbox series

Patch

diff --git a/src/common/tracer.h b/src/common/tracer.h
index 2affd6ab..8e18c9b5 100644
--- a/src/common/tracer.h
+++ b/src/common/tracer.h
@@ -26,6 +26,8 @@ 
 #define LTTNG_RFLAG_EXTENDED		RING_BUFFER_RFLAG_END
 #define LTTNG_RFLAG_END			(LTTNG_RFLAG_EXTENDED << 1)
 
+#define LTTNG_TRACE_PRINTF_BUFSIZE	512
+
 /*
  * LTTng client type enumeration. Used by the consumer to map the
  * callbacks from its own address space.
diff --git a/src/lib/lttng-ust-tracepoint/tracef.c b/src/lib/lttng-ust-tracepoint/tracef.c
index c05c7811..92911e1d 100644
--- a/src/lib/lttng-ust-tracepoint/tracef.c
+++ b/src/lib/lttng-ust-tracepoint/tracef.c
@@ -7,6 +7,7 @@ 
 #define _LGPL_SOURCE
 #include <stdio.h>
 #include "common/macros.h"
+#include "common/tracer.h"
 
 /* The tracepoint definition is public, but the provider definition is hidden. */
 #define LTTNG_UST_TRACEPOINT_PROVIDER_HIDDEN_DEFINITION
@@ -15,39 +16,22 @@ 
 #define LTTNG_UST_TRACEPOINT_DEFINE
 #include "lttng-ust-tracef-provider.h"
 
-static inline
-void lttng_ust___vtracef(const char *fmt, va_list ap)
-	__attribute__((always_inline, format(printf, 1, 0)));
-static inline
-void lttng_ust___vtracef(const char *fmt, va_list ap)
-{
-	char *msg;
-	const int len = vasprintf(&msg, fmt, ap);
-
-	/* len does not include the final \0 */
-	if (len < 0)
-		goto end;
-	lttng_ust_tracepoint_cb_lttng_ust_tracef___event(msg, len,
-		LTTNG_UST_CALLER_IP());
-	free(msg);
-end:
-	return;
-}
+#include "tracelog-internal.h"
 
 void lttng_ust__vtracef(const char *fmt, va_list ap)
 	__attribute__((format(printf, 1, 0)));
 void lttng_ust__vtracef(const char *fmt, va_list ap)
 {
-	lttng_ust___vtracef(fmt, ap);
+	LTTNG_UST_TRACELOG_VALIST(fmt, ap,
+		lttng_ust_tracepoint_cb_lttng_ust_tracef___event,
+		msg, len, LTTNG_UST_CALLER_IP());
 }
 
 void lttng_ust__tracef(const char *fmt, ...)
 	__attribute__((format(printf, 1, 2)));
 void lttng_ust__tracef(const char *fmt, ...)
 {
-	va_list ap;
-
-	va_start(ap, fmt);
-	lttng_ust___vtracef(fmt, ap);
-	va_end(ap);
+	LTTNG_UST_TRACELOG_VARARG(fmt,
+		lttng_ust_tracepoint_cb_lttng_ust_tracef___event,
+		msg, len, LTTNG_UST_CALLER_IP());
 }
diff --git a/src/lib/lttng-ust-tracepoint/tracelog-internal.h b/src/lib/lttng-ust-tracepoint/tracelog-internal.h
new file mode 100644
index 00000000..291ff27c
--- /dev/null
+++ b/src/lib/lttng-ust-tracepoint/tracelog-internal.h
@@ -0,0 +1,83 @@ 
+/*
+ * SPDX-License-Identifier: MIT
+ *
+ * Copyright (C) 2013-2014 Mathieu Desnoyers <mathieu.desnoyers at efficios.com>
+ * Copyright (C) 2021 Norbert Lange <nolange79 at gmail.com>
+ *
+ * Shared helper macro for tracelog and tracef
+ */
+
+#define LTTNG_UST_TRACELOG_VARARG(fmt, callback, ...) \
+	va_list ap; \
+	char local_buf[LTTNG_TRACE_PRINTF_BUFSIZE]; \
+	int len; \
+	char *msg = local_buf; \
+	size_t buflen = sizeof(local_buf); \
+	char *alloc_buff = NULL; \
+\
+	if (caa_unlikely(fmt[0] == '%' && fmt[1] == 's' && fmt[2] == '\0')) { \
+		va_start(ap, fmt); \
+		msg = va_arg(ap, char *); \
+		va_end(ap); \
+		len = strlen(msg); \
+	} else \
+		for(;;) { \
+			va_start(ap, fmt); \
+			len = vsnprintf(msg, buflen, fmt, ap); \
+			va_end(ap); \
+\
+			if (caa_unlikely(len >= (int)sizeof(local_buf) && !alloc_buff)) { \
+				buflen = (size_t)len + 1U; \
+				len = -1; \
+				alloc_buff = (char *)malloc(buflen); \
+				msg = alloc_buff; \
+				if (!alloc_buff) \
+					break; \
+			} else \
+				break; \
+		} \
+\
+	/* len does not include the final \0 */ \
+	if (caa_likely(len >= 0)) { \
+		callback(__VA_ARGS__); \
+	} \
+	/* Dont call a potentially instrumented forbidden free needlessly. */ \
+	if (caa_unlikely(alloc_buff)) \
+		free(alloc_buff);
+
+#define LTTNG_UST_TRACELOG_VALIST(fmt, ap, callback, ...) \
+	char local_buf[LTTNG_TRACE_PRINTF_BUFSIZE]; \
+	int len; \
+	char *msg = local_buf; \
+	size_t buflen = sizeof(local_buf); \
+	char *alloc_buff = NULL; \
+\
+	if (caa_unlikely(fmt[0] == '%' && fmt[1] == 's' && fmt[2] == '\0')) { \
+		msg = va_arg(ap, char *); \
+		len = strlen(msg); \
+	} else \
+		for(;;) { \
+			va_list ap2; \
+\
+			va_copy(ap2, ap); \
+			len = vsnprintf(msg, buflen, fmt, ap2); \
+			va_end(ap2); \
+\
+			if (caa_unlikely(len >= (int)sizeof(local_buf) && !alloc_buff)) { \
+				buflen = (size_t)len + 1U; \
+				len = -1; \
+				alloc_buff = (char *)malloc(buflen); \
+				msg = alloc_buff; \
+				if (!alloc_buff) \
+					break; \
+			} else \
+				break; \
+		} \
+\
+	/* len does not include the final \0 */ \
+	if (caa_likely(len >= 0)) { \
+		callback(__VA_ARGS__); \
+	} \
+	/* Dont call a potentially instrumented forbidden free needlessly. */ \
+	if (caa_unlikely(alloc_buff)) \
+		free(alloc_buff);
diff --git a/src/lib/lttng-ust-tracepoint/tracelog.c b/src/lib/lttng-ust-tracepoint/tracelog.c
index 8147d7a3..bd38032c 100644
--- a/src/lib/lttng-ust-tracepoint/tracelog.c
+++ b/src/lib/lttng-ust-tracepoint/tracelog.c
@@ -7,6 +7,7 @@ 
 #define _LGPL_SOURCE
 #include <stdio.h>
 #include "common/macros.h"
+#include "common/tracer.h"
 
 /* The tracepoint definition is public, but the provider definition is hidden. */
 #define LTTNG_UST_TRACEPOINT_PROVIDER_HIDDEN_DEFINITION
@@ -15,32 +16,9 @@ 
 #define LTTNG_UST_TRACEPOINT_DEFINE
 #include "lttng-ust-tracelog-provider.h"
 
+#include "tracelog-internal.h"
+
 #define LTTNG_UST_TRACELOG_CB(level) \
-	static inline \
-	void lttng_ust___vtracelog_##level(const char *file, \
-			int line, const char *func, \
-			const char *fmt, va_list ap) \
-		__attribute__((always_inline, format(printf, 4, 0))); \
-	\
-	static inline \
-	void lttng_ust___vtracelog_##level(const char *file, \
-			int line, const char *func, \
-			const char *fmt, va_list ap) \
-	{ \
-		char *msg; \
-		const int len = vasprintf(&msg, fmt, ap); \
-		\
-		/* len does not include the final \0 */ \
-		if (len < 0) \
-			goto end; \
-		lttng_ust_tracepoint_cb_lttng_ust_tracelog___##level(file, \
-			line, func, msg, len, \
-			LTTNG_UST_CALLER_IP()); \
-		free(msg); \
-	end: \
-		return; \
-	} \
-	\
 	void lttng_ust__vtracelog_##level(const char *file, \
 			int line, const char *func, \
 			const char *fmt, va_list ap) \
@@ -53,7 +31,9 @@ 
 			int line, const char *func, \
 			const char *fmt, va_list ap) \
 	{ \
-		lttng_ust___vtracelog_##level(file, line, func, fmt, ap); \
+		LTTNG_UST_TRACELOG_VALIST(fmt, ap, \
+			lttng_ust_tracepoint_cb_lttng_ust_tracelog___##level, \
+			file, line, func, msg, len, LTTNG_UST_CALLER_IP()); \
 	} \
 	\
 	void lttng_ust__tracelog_##level(const char *file, \
@@ -68,11 +48,9 @@ 
 			int line, const char *func, \
 			const char *fmt, ...) \
 	{ \
-		va_list ap; \
-		\
-		va_start(ap, fmt); \
-		lttng_ust___vtracelog_##level(file, line, func, fmt, ap); \
-		va_end(ap); \
+		LTTNG_UST_TRACELOG_VARARG(fmt, \
+			lttng_ust_tracepoint_cb_lttng_ust_tracelog___##level, \
+			file, line, func, msg, len, LTTNG_UST_CALLER_IP()); \
 	}
 
 LTTNG_UST_TRACELOG_CB(LTTNG_UST_TRACEPOINT_LOGLEVEL_EMERG)