[PATCH] log: Allow LOG_DEBUG to always enable log output

[Heinrich Schuchardt]

On 7/27/20 4:27 AM, Simon Glass wrote:
> At present if CONFIG_LOG enabled, putting LOG_DEBUG at the top of a file
> (before log.h inclusion) causes _log() to be executed for every log()
> call, regardless of the build- or run-time logging level.
>
> However there is no guarantee that the log record will actually be
> displayed. If the current log level is lower than LOGL_DEBUG then it will
> not be.
>
> Add a way to signal that the log record should always be displayed and
> update log_passes_filters() to handle this.
>
> Signed-off-by: Simon Glass <sjg at chromium.org>

Hello Simon,

we have different debug levels:

LOGL_DEBUG
LOGL_DEBUG_CONTENT
LOGL_DEBUG_IO

If I understand you right, with your patch putting #define LOG_DEBUG at
the top of the file enables all of these. This may be more than I want.

Wouldn't it be more flexible if we could put something like:

#define LOG_DEBUG LOGL_DEBUG

at the top of the file if we want logging up to level 7 in this file.

Best regards

Heinrich

Best regards

> ---
>
>  common/log.c           | 11 ++++++++---
>  doc/README.log         | 10 ++++------
>  include/log.h          | 16 ++++++++++++----
>  test/log/syslog_test.c |  2 +-
>  4 files changed, 25 insertions(+), 14 deletions(-)
>
> diff --git a/common/log.c b/common/log.c
> index 734d26de4a..5ff8245922 100644
> --- a/common/log.c
> +++ b/common/log.c
> @@ -156,16 +156,20 @@ static bool log_has_file(const char *file_list, const char *file)
>  static bool log_passes_filters(struct log_device *ldev, struct log_rec *rec)
>  {
>  	struct log_filter *filt;
> +	int level = rec->level & LOGL_LEVEL_MASK;
> +
> +	if (rec->force_debug && level <= LOGL_DEBUG)
> +		return true;
>
>  	/* If there are no filters, filter on the default log level */
>  	if (list_empty(&ldev->filter_head)) {
> -		if (rec->level > gd->default_log_level)
> +		if (level > gd->default_log_level)
>  			return false;
>  		return true;
>  	}
>
>  	list_for_each_entry(filt, &ldev->filter_head, sibling_node) {
> -		if (rec->level > filt->max_level)
> +		if (level > filt->max_level)
>  			continue;
>  		if ((filt->flags & LOGFF_HAS_CAT) &&
>  		    !log_has_cat(filt->cat_list, rec->cat))
> @@ -208,7 +212,8 @@ int _log(enum log_category_t cat, enum log_level_t level, const char *file,
>  	va_list args;
>
>  	rec.cat = cat;
> -	rec.level = level;
> +	rec.level = level & LOGL_LEVEL_MASK;
> +	rec.force_debug = level & LOGL_FORCE_DEBUG;
>  	rec.file = file;
>  	rec.line = line;
>  	rec.func = func;
> diff --git a/doc/README.log b/doc/README.log
> index ba838824a9..554e99ca4c 100644
> --- a/doc/README.log
> +++ b/doc/README.log
> @@ -77,12 +77,10 @@ Sometimes it is useful to turn on logging just in one file. You can use this:
>
>     #define LOG_DEBUG
>
> -to enable building in of all logging statements in a single file. Put it at
> -the top of the file, before any #includes.
> -
> -To actually get U-Boot to output this you need to also set the default logging
> -level - e.g. set CONFIG_LOG_DEFAULT_LEVEL to 7 (LOGL_DEBUG) or more. Otherwise
> -debug output is suppressed and will not be generated.
> +to enable building in of all debug logging statements in a single file. Put it
> +at the top of the file, before any #includes. This overrides any log-level
> +setting in U-Boot, including CONFIG_LOG_DEFAULT_LEVEL, but just for that file.
> +All logging statements, up to and including LOGL_DEBUG, will be displayed.
>
>
>  Convenience functions
> diff --git a/include/log.h b/include/log.h
> index 2859ce1f2e..63052f74eb 100644
> --- a/include/log.h
> +++ b/include/log.h
> @@ -33,6 +33,9 @@ enum log_level_t {
>  	LOGL_COUNT,
>  	LOGL_NONE,
>
> +	LOGL_LEVEL_MASK = 0xf,	/* Mask for valid log levels */
> +	LOGL_FORCE_DEBUG = 0x10, /* Mask to force output due to LOG_DEBUG */
> +
>  	LOGL_FIRST = LOGL_EMERG,
>  	LOGL_MAX = LOGL_DEBUG_IO,
>  };
> @@ -133,7 +136,7 @@ static inline int _log_nop(enum log_category_t cat, enum log_level_t level,
>
>  #if CONFIG_IS_ENABLED(LOG)
>  #ifdef LOG_DEBUG
> -#define _LOG_DEBUG	1
> +#define _LOG_DEBUG	LOGL_FORCE_DEBUG
>  #else
>  #define _LOG_DEBUG	0
>  #endif
> @@ -141,9 +144,9 @@ static inline int _log_nop(enum log_category_t cat, enum log_level_t level,
>  /* Emit a log record if the level is less that the maximum */
>  #define log(_cat, _level, _fmt, _args...) ({ \
>  	int _l = _level; \
> -	if (CONFIG_IS_ENABLED(LOG) && (_l <= _LOG_MAX_LEVEL || _LOG_DEBUG)) \
> -		_log((enum log_category_t)(_cat), _l, __FILE__, __LINE__, \
> -		      __func__, \
> +	if (CONFIG_IS_ENABLED(LOG) && (_LOG_DEBUG || _l <= _LOG_MAX_LEVEL)) \
> +		_log((enum log_category_t)(_cat), _l | _LOG_DEBUG, __FILE__, \
> +		     __LINE__, __func__, \
>  		      pr_fmt(_fmt), ##_args); \
>  	})
>  #else
> @@ -279,8 +282,12 @@ void __assert_fail(const char *assertion, const char *file, unsigned int line,
>   * Memebers marked as 'allocated' are allocated (e.g. via strdup()) by the log
>   * system.
>   *
> + * TODO(sjg at chromium.org): Compress this struct down a bit to reduce space, e.g.
> + * a single u32 for cat, level, line and force_debug
> + *
>   * @cat: Category, representing a uclass or part of U-Boot
>   * @level: Severity level, less severe is higher
> + * @force_debug: Force output of debug
>   * @file: Name of file where the log record was generated (not allocated)
>   * @line: Line number where the log record was generated
>   * @func: Function where the log record was generated (not allocated)
> @@ -289,6 +296,7 @@ void __assert_fail(const char *assertion, const char *file, unsigned int line,
>  struct log_rec {
>  	enum log_category_t cat;
>  	enum log_level_t level;
> +	bool force_debug;
>  	const char *file;
>  	int line;
>  	const char *func;
> diff --git a/test/log/syslog_test.c b/test/log/syslog_test.c
> index 120a8b2537..df239d1e8d 100644
> --- a/test/log/syslog_test.c
> +++ b/test/log/syslog_test.c
> @@ -276,7 +276,7 @@ static int log_test_syslog_nodebug(struct unit_test_state *uts)
>  	sandbox_eth_set_tx_handler(0, sb_log_tx_handler);
>  	/* Used by ut_assert macros in the tx_handler */
>  	sandbox_eth_set_priv(0, &env);
> -	log_debug("testing %s\n", "log_debug");
> +	log_content("testing %s\n", "log_debug");
>  	sandbox_eth_set_tx_handler(0, NULL);
>  	/* Check that the callback function was not called */
>  	ut_assertnonnull(env.expected);
>