From: Norbert Lange Date: Mon, 1 Aug 2022 14:35:24 +0000 (+0200) Subject: Improve tracef/tracelog to use the stack for small strings X-Git-Url: http://git.lttng.org/?p=lttng-ust.git;a=commitdiff_plain;h=1c0569ec0d094571d181d1fce53ecfce8877614f Improve tracef/tracelog to use the stack for small strings 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 Signed-off-by: Mathieu Desnoyers --- 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/tracef.c b/src/lib/lttng-ust/tracef.c index c05c7811..92911e1d 100644 --- a/src/lib/lttng-ust/tracef.c +++ b/src/lib/lttng-ust/tracef.c @@ -7,6 +7,7 @@ #define _LGPL_SOURCE #include #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/tracelog-internal.h b/src/lib/lttng-ust/tracelog-internal.h new file mode 100644 index 00000000..e119744d --- /dev/null +++ b/src/lib/lttng-ust/tracelog-internal.h @@ -0,0 +1,93 @@ +/* + * SPDX-License-Identifier: MIT + * + * Copyright (C) 2013-2014 Mathieu Desnoyers + * Copyright (C) 2021 Norbert Lange + * + * Shared helper macro for tracelog and tracef. + */ + +#define LTTNG_UST_TRACELOG_VARARG(fmt, callback, ...) \ + do { \ + char local_buf[LTTNG_TRACE_PRINTF_BUFSIZE]; \ + char *alloc_buff = NULL, *msg = local_buf; \ + size_t len = 0; \ + va_list ap; \ +\ + 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 { \ + size_t buflen = sizeof(local_buf); \ + int ret; \ +\ + /* On-stack buffer attempt */ \ + va_start(ap, fmt); \ + ret = vsnprintf(msg, buflen, fmt, ap); \ + va_end(ap); \ + if (caa_unlikely(ret < 0)) \ + break; \ + len = (size_t)ret; \ +\ + if (caa_unlikely(len >= sizeof(local_buf))) { \ + buflen = len + 1; \ + alloc_buff = (char *)malloc(buflen); \ + if (!alloc_buff) \ + goto end; \ + msg = alloc_buff; \ + va_start(ap, fmt); \ + ret = vsnprintf(msg, buflen, fmt, ap); \ + va_end(ap); \ + lttng_ust_runtime_bug_on(ret < 0 || (size_t)ret != buflen - 1); \ + len = (size_t)ret; \ + } \ + } \ +\ + callback(__VA_ARGS__); \ +end: \ + /* Don't call a potentially instrumented forbidden free needlessly. */ \ + if (caa_unlikely(alloc_buff)) \ + free(alloc_buff); \ + } while(0) + +#define LTTNG_UST_TRACELOG_VALIST(fmt, ap, callback, ...) \ + do { \ + char local_buf[LTTNG_TRACE_PRINTF_BUFSIZE]; \ + char *alloc_buff = NULL, *msg = local_buf; \ + size_t len = 0; \ +\ + if (caa_unlikely(fmt[0] == '%' && fmt[1] == 's' && fmt[2] == '\0')) { \ + msg = va_arg(ap, char *); \ + len = strlen(msg); \ + } else { \ + size_t buflen = sizeof(local_buf); \ + va_list ap2; \ + int ret; \ +\ + va_copy(ap2, ap); \ + ret = vsnprintf(msg, buflen, fmt, ap2); \ + va_end(ap2); \ + if (caa_unlikely(ret < 0)) \ + break; \ + len = (size_t)ret; \ +\ + if (caa_unlikely(len >= sizeof(local_buf))) { \ + buflen = len + 1; \ + alloc_buff = (char *)malloc(buflen); \ + if (!alloc_buff) \ + goto end; \ + msg = alloc_buff; \ + ret = vsnprintf(msg, buflen, fmt, ap); \ + lttng_ust_runtime_bug_on(ret < 0 || (size_t)ret != buflen - 1); \ + len = (size_t)ret; \ + } \ + } \ +\ + callback(__VA_ARGS__); \ +end: \ + /* Don't call a potentially instrumented forbidden free needlessly. */ \ + if (caa_unlikely(alloc_buff)) \ + free(alloc_buff); \ + } while (0) diff --git a/src/lib/lttng-ust/tracelog.c b/src/lib/lttng-ust/tracelog.c index 8147d7a3..bd38032c 100644 --- a/src/lib/lttng-ust/tracelog.c +++ b/src/lib/lttng-ust/tracelog.c @@ -7,6 +7,7 @@ #define _LGPL_SOURCE #include #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)