[dpdk-dev] [PATCH v2] log: respect rte_openlog_stream calls before rte_eal_init

[John Ousterhout <ouster@cs.stanford.edu>]

Before this patch, application-specific loggers could not be
installed before rte_eal_init completed (the initialization process
called rte_openlog_stream, overwriting any previously installed
logger). This made it impossible for an application to capture the
initial log messages generated during rte_eal_init. This patch changes
initialization so that information from a previous call to
rte_openlog_stream is not lost. Specifically:
* The default log stream is now maintained separately from an
  application-specific log stream installed with rte_openlog_stream.
* rte_eal_common_log_init has been renamed to rte_eal_log_set_default,
  since this is all it does. It no longer invokes rte_openlog_stream; it
  just updates the default stream. Also, this method now returns void,
  rather than int, since there are no errors.
* The "early log" mechanism (e.g. rte_eal_log_early_init) has been
  removed; all of the desired functionality can be achieved by calling
  rte_eal_log_set_default.

Signed-off-by: John Ousterhout <ouster@cs.stanford.edu>
----
v2:
* Removed the early log mechanism, renamed rte_eal_common_log_init.

Note: I see from the code that Linux and BSD set different default streams:
Linux uses stdout, while BSD uses stderr. This patch retains the distinction,
though I'm not sure why it is there.
---
 lib/librte_eal/bsdapp/eal/eal.c         |  3 +--
 lib/librte_eal/bsdapp/eal/eal_log.c     | 11 +--------
 lib/librte_eal/common/eal_common_log.c  | 19 +++++++---------
 lib/librte_eal/common/eal_private.h     | 16 ++++---------
 lib/librte_eal/common/include/rte_log.h |  2 +-
 lib/librte_eal/linuxapp/eal/eal.c       |  3 +--
 lib/librte_eal/linuxapp/eal/eal_log.c   | 40 +--------------------------------
 7 files changed, 17 insertions(+), 77 deletions(-)

diff --git a/lib/librte_eal/bsdapp/eal/eal.c b/lib/librte_eal/bsdapp/eal/eal.c
index a0c8f8c..a1ef75b 100644
--- a/lib/librte_eal/bsdapp/eal/eal.c
+++ b/lib/librte_eal/bsdapp/eal/eal.c
@@ -501,8 +501,7 @@ rte_eal_init(int argc, char **argv)
 
 	thread_id = pthread_self();
 
-	if (rte_eal_log_early_init() < 0)
-		rte_panic("Cannot init early logs\n");
+	rte_eal_log_set_default(stderr);
 
 	eal_log_level_parse(argc, argv);
 
diff --git a/lib/librte_eal/bsdapp/eal/eal_log.c b/lib/librte_eal/bsdapp/eal/eal_log.c
index a425f7a..6b2c6da 100644
--- a/lib/librte_eal/bsdapp/eal/eal_log.c
+++ b/lib/librte_eal/bsdapp/eal/eal_log.c
@@ -44,14 +44,5 @@
 int
 rte_eal_log_init(const char *id __rte_unused, int facility __rte_unused)
 {
-	if (rte_eal_common_log_init(stderr) < 0)
-		return -1;
-	return 0;
-}
-
-int
-rte_eal_log_early_init(void)
-{
-	rte_openlog_stream(stderr);
-	return 0;
+	rte_eal_set_default(stderr);
 }
diff --git a/lib/librte_eal/common/eal_common_log.c b/lib/librte_eal/common/eal_common_log.c
index 967991a..2181cfa 100644
--- a/lib/librte_eal/common/eal_common_log.c
+++ b/lib/librte_eal/common/eal_common_log.c
@@ -48,11 +48,12 @@ struct rte_logs rte_logs = {
 	.file = NULL,
 };
 
+/* Stream to use for logging if rte_logs.file is NULL */
 static FILE *default_log_stream;
 
 /**
  * This global structure stores some informations about the message
- * that is currently beeing processed by one lcore
+ * that is currently being processed by one lcore
  */
 struct log_cur_msg {
 	uint32_t loglevel; /**< log level - see rte_log.h */
@@ -68,10 +69,7 @@ static RTE_DEFINE_PER_LCORE(struct log_cur_msg, log_cur_msg);
 int
 rte_openlog_stream(FILE *f)
 {
-	if (f == NULL)
-		rte_logs.file = default_log_stream;
-	else
-		rte_logs.file = f;
+	rte_logs.file = f;
 	return 0;
 }
 
@@ -127,6 +125,8 @@ rte_vlog(uint32_t level, uint32_t logtype, const char *format, va_list ap)
 {
 	int ret;
 	FILE *f = rte_logs.file;
+	if (f == NULL)
+		f = default_log_stream;
 
 	if ((level > rte_logs.level) || !(logtype & rte_logs.type))
 		return 0;
@@ -158,17 +158,14 @@ rte_log(uint32_t level, uint32_t logtype, const char *format, ...)
 }
 
 /*
- * called by environment-specific log init function
+ * Called by environment-specific initialization functions.
  */
-int
-rte_eal_common_log_init(FILE *default_log)
+void
+rte_eal_log_set_default(FILE *default_log)
 {
 	default_log_stream = default_log;
-	rte_openlog_stream(default_log);
 
 #if RTE_LOG_LEVEL >= RTE_LOG_DEBUG
 	RTE_LOG(NOTICE, EAL, "Debug logs available - lower performance\n");
 #endif
-
-	return 0;
 }
diff --git a/lib/librte_eal/common/eal_private.h b/lib/librte_eal/common/eal_private.h
index 19f7535..a037994 100644
--- a/lib/librte_eal/common/eal_private.h
+++ b/lib/librte_eal/common/eal_private.h
@@ -47,7 +47,9 @@
 int rte_eal_memzone_init(void);
 
 /**
- * Common log initialization function (private to eal).
+ * Common log initialization function (private to eal).  Determines
+ * where log data is written when no call to eal_openlog_stream is
+ * in effect.
  *
  * @param default_log
  *   The default log stream to be used.
@@ -55,7 +57,7 @@ int rte_eal_memzone_init(void);
  *   - 0 on success
  *   - Negative on error
  */
-int rte_eal_common_log_init(FILE *default_log);
+void rte_eal_log_set_default(FILE *default_log);
 
 /**
  * Fill configuration with number of physical and logical processors
@@ -97,16 +99,6 @@ int rte_eal_memory_init(void);
 int rte_eal_timer_init(void);
 
 /**
- * Init early logs
- *
- * This function is private to EAL.
- *
- * @return
- *   0 on success, negative on error
- */
-int rte_eal_log_early_init(void);
-
-/**
  * Init the default log stream
  *
  * This function is private to EAL.
diff --git a/lib/librte_eal/common/include/rte_log.h b/lib/librte_eal/common/include/rte_log.h
index 919563c..d99baf3 100644
--- a/lib/librte_eal/common/include/rte_log.h
+++ b/lib/librte_eal/common/include/rte_log.h
@@ -54,7 +54,7 @@ extern "C" {
 struct rte_logs {
 	uint32_t type;  /**< Bitfield with enabled logs. */
 	uint32_t level; /**< Log level. */
-	FILE *file;     /**< Pointer to current FILE* for logs. */
+	FILE *file;     /**< Output file set by rte_openlog_stream, or NULL. */
 };
 
 /** Global log informations */
diff --git a/lib/librte_eal/linuxapp/eal/eal.c b/lib/librte_eal/linuxapp/eal/eal.c
index d5b81a3..4bd2439 100644
--- a/lib/librte_eal/linuxapp/eal/eal.c
+++ b/lib/librte_eal/linuxapp/eal/eal.c
@@ -748,8 +748,7 @@ rte_eal_init(int argc, char **argv)
 
 	thread_id = pthread_self();
 
-	if (rte_eal_log_early_init() < 0)
-		rte_panic("Cannot init early logs\n");
+	rte_eal_log_set_default(stdout);
 
 	eal_log_level_parse(argc, argv);
 
diff --git a/lib/librte_eal/linuxapp/eal/eal_log.c b/lib/librte_eal/linuxapp/eal/eal_log.c
index d391100..4a6690a 100644
--- a/lib/librte_eal/linuxapp/eal/eal_log.c
+++ b/lib/librte_eal/linuxapp/eal/eal_log.c
@@ -97,45 +97,7 @@ rte_eal_log_init(const char *id, int facility)
 
 	openlog(id, LOG_NDELAY | LOG_PID, facility);
 
-	if (rte_eal_common_log_init(log_stream) < 0)
-		return -1;
-
-	return 0;
-}
-
-/* early logs */
-
-/*
- * early log function, used before rte_eal_log_init
- */
-static ssize_t
-early_log_write(__attribute__((unused)) void *c, const char *buf, size_t size)
-{
-	ssize_t ret;
-	ret = fwrite(buf, size, 1, stdout);
-	fflush(stdout);
-	if (ret == 0)
-		return -1;
-	return ret;
-}
-
-static cookie_io_functions_t early_log_func = {
-	.write = early_log_write,
-};
-static FILE *early_log_stream;
+	rte_eal_log_set_default(log_stream);
 
-/*
- * init the log library, called by rte_eal_init() to enable early
- * logs
- */
-int
-rte_eal_log_early_init(void)
-{
-	early_log_stream = fopencookie(NULL, "w+", early_log_func);
-	if (early_log_stream == NULL) {
-		printf("Cannot configure early_log_stream\n");
-		return -1;
-	}
-	rte_openlog_stream(early_log_stream);
 	return 0;
 }
-- 
2.8.3