[RFC] drm: Enable dynamic debug for DRM_[DEV]_DEBUG*
Daniel Vetter
daniel at ffwll.ch
Mon Dec 5 16:31:24 UTC 2016
On Mon, Dec 05, 2016 at 11:24:44AM +0000, Robert Bragg wrote:
> Forgot to send to dri-devel when I first sent this out...
>
> The few times I've looked at using DRM_DEBUG messages, I haven't found
> them very helpful considering how noisy some of the categories are. More
> than once now I've preferred to go in and modify individual files to
> affect what messages I see and re-build.
>
> After recently converting some of the i915_perf.c messages to use
> DRM_DEBUG, I thought I'd see if DRM_DEBUG could be updated to have a bit
> more fine grained control than the current category flags.
>
> A few things to note with this first iteration:
>
> - I haven't looked to see what affect the change has on linked object
> sizes.
>
> - It seems like it could be nice if dynamic debug could effectively make
> the drm_debug parameter redundant but dynamic debug doesn't give us a
> way to categorise messages so maybe we'd want to consider including
> categories in messages something like:
>
> "[drm][kms] No FB found"
>
> This way all kms messages could be enabled via:
> echo "format [kms] +p" > dynamic_debug/control
>
> Note with this simple scheme categories would no longer be mutually
> exclusive which could be a nice bonus.
Really nice idea, and I agree that unifying drm.debug with dynamic debug
in some way would be useful. We could implement your idea by reworking the
existing debug helpers to auto-prepend the right string. That also opens
up the door for much more fine-grained bucketing maybe, only challenge is
that we should document things somewhere.
> Since it would involve changing the output format, I wonder how
> concerned others might be about breaking some userspace (maybe CI test
> runners) that for some reason grep for specific messages?
I think the only thing we have to keep working (somehow) is drm.debug. The
exact output format doesn't really matter at all. Getting drm.debug to
work when dynamic debugging is enabled probably requires exporting some
functions, so that we can set the right ddebug options from the drm.debug
mod-option write handler. There's special mod-option macros that allow you
to specify write handlers, so that part is ok.
The other bit of backwards compat we imo need is that by default we should
still keep drm.debug working, even when dynamic debugging is disabled.
Having a third option that uses no_printk or similar (to get rid of all
the debug strings and dead-code-eliminate all the related output code)
> --- >8 --- (git am --scissors)
>
> Dynamic debug messages (ref: Documentation/dynamic-debug-howto.txt)
> allow fine grained control over which debug messages are enabled with
> runtime control through /sysfs/kernel/debug/dynamic_debug/control
>
> This provides more control than the current drm.drm_debug parameter
> which for some use cases is impractical to use given how chatty
> some drm debug categories are.
>
> For example all debug messages in i915_drm.c can be enabled with:
> echo "file i915_perf.c +p" > dynamic_debug/control
>
> This aims to maintain compatibility with controlling debug messages
> using the drm_debug parameter. The new dynamic debug macros are called
> by default but conditionally calling [dev_]printk if the category flag
> is set (side stepping the dynamic debug condition in that case)
>
> This removes the drm_[dev_]printk wrappers considering that the dynamic
> debug macros are only useful if they can track the __FILE__, __func__
> and __LINE__ where they are called. The wrapper didn't seem necessary in
> the DRM_UT_NONE case with no category flag.
>
> The output format should be compatible, unless the _DEV macros are
> passed a NULL dev pointer considering how the core.c dev_printk
> implementation adds "(NULL device *)" to the message in that case while
> the drm wrapper would fallback to a plain printk in this case.
> Previously some of non-dev drm debug macros were defined in terms of
> passing NULL to a dev version but that's avoided now due to this
> difference.
>
> Signed-off-by: Robert Bragg <robert at sixbynine.org>
> Cc: dri-devel at lists.freedesktop.org
> Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> ---
> drivers/gpu/drm/drm_drv.c | 47 -------------
> include/drm/drmP.h | 168 +++++++++++++++++++++++++++++-----------------
> 2 files changed, 108 insertions(+), 107 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
> index f74b7d0..25d00aa 100644
> --- a/drivers/gpu/drm/drm_drv.c
> +++ b/drivers/gpu/drm/drm_drv.c
> @@ -65,53 +65,6 @@ static struct idr drm_minors_idr;
>
> static struct dentry *drm_debugfs_root;
>
> -#define DRM_PRINTK_FMT "[" DRM_NAME ":%s]%s %pV"
> -
> -void drm_dev_printk(const struct device *dev, const char *level,
> - unsigned int category, const char *function_name,
> - const char *prefix, const char *format, ...)
> -{
> - struct va_format vaf;
> - va_list args;
> -
> - if (category != DRM_UT_NONE && !(drm_debug & category))
> - return;
> -
> - va_start(args, format);
> - vaf.fmt = format;
> - vaf.va = &args;
> -
> - if (dev)
> - dev_printk(level, dev, DRM_PRINTK_FMT, function_name, prefix,
> - &vaf);
> - else
> - printk("%s" DRM_PRINTK_FMT, level, function_name, prefix, &vaf);
> -
> - va_end(args);
> -}
> -EXPORT_SYMBOL(drm_dev_printk);
> -
> -void drm_printk(const char *level, unsigned int category,
> - const char *format, ...)
> -{
> - struct va_format vaf;
> - va_list args;
> -
> - if (category != DRM_UT_NONE && !(drm_debug & category))
> - return;
> -
> - va_start(args, format);
> - vaf.fmt = format;
> - vaf.va = &args;
> -
> - printk("%s" "[" DRM_NAME ":%ps]%s %pV",
> - level, __builtin_return_address(0),
> - strcmp(level, KERN_ERR) == 0 ? " *ERROR*" : "", &vaf);
> -
> - va_end(args);
> -}
> -EXPORT_SYMBOL(drm_printk);
> -
> /*
> * DRM Minors
> * A DRM device can provide several char-dev interfaces on the DRM-Major. Each
> diff --git a/include/drm/drmP.h b/include/drm/drmP.h
> index a9cfd33..680f359 100644
> --- a/include/drm/drmP.h
> +++ b/include/drm/drmP.h
> @@ -58,6 +58,7 @@
> #include <linux/vmalloc.h>
> #include <linux/workqueue.h>
> #include <linux/dma-fence.h>
> +#include <linux/dynamic_debug.h>
>
> #include <asm/mman.h>
> #include <asm/pgalloc.h>
> @@ -129,7 +130,6 @@ struct dma_buf_attachment;
> * run-time by echoing the debug value in its sysfs node:
> * # echo 0xf > /sys/module/drm/parameters/debug
> */
> -#define DRM_UT_NONE 0x00
> #define DRM_UT_CORE 0x01
> #define DRM_UT_DRIVER 0x02
> #define DRM_UT_KMS 0x04
> @@ -146,25 +146,22 @@ struct dma_buf_attachment;
> /** \name Macros to make printk easier */
> /*@{*/
>
> -#define _DRM_PRINTK(once, level, fmt, ...) \
> - do { \
> - printk##once(KERN_##level "[" DRM_NAME "] " fmt, \
> - ##__VA_ARGS__); \
> - } while (0)
> +#define _DRM_FMT_PREFIX "[" DRM_NAME "] "
> +#define _DRM_FMT_FUNC_PREFIX "[" DRM_NAME ":%s] "
>
> #define DRM_INFO(fmt, ...) \
> - _DRM_PRINTK(, INFO, fmt, ##__VA_ARGS__)
> + pr_info(_DRM_FMT_PREFIX fmt, ##__VA_ARGS__)
> #define DRM_NOTE(fmt, ...) \
> - _DRM_PRINTK(, NOTICE, fmt, ##__VA_ARGS__)
> + pr_notice(_DRM_FMT_PREFIX fmt, ##__VA_ARGS__)
> #define DRM_WARN(fmt, ...) \
> - _DRM_PRINTK(, WARNING, fmt, ##__VA_ARGS__)
> + pr_warn(_DRM_FMT_PREFIX fmt, ##__VA_ARGS__)
>
> #define DRM_INFO_ONCE(fmt, ...) \
> - _DRM_PRINTK(_once, INFO, fmt, ##__VA_ARGS__)
> + pr_info_once(_DRM_FMT_PREFIX fmt, ##__VA_ARGS__)
> #define DRM_NOTE_ONCE(fmt, ...) \
> - _DRM_PRINTK(_once, NOTICE, fmt, ##__VA_ARGS__)
> + pr_notice_once(_DRM_FMT_PREFIX fmt, ##__VA_ARGS__)
> #define DRM_WARN_ONCE(fmt, ...) \
> - _DRM_PRINTK(_once, WARNING, fmt, ##__VA_ARGS__)
> + pr_warn_once(_DRM_FMT_PREFIX fmt, ##__VA_ARGS__)
>
> /**
> * Error output.
> @@ -173,10 +170,11 @@ struct dma_buf_attachment;
> * \param arg arguments
> */
> #define DRM_DEV_ERROR(dev, fmt, ...) \
> - drm_dev_printk(dev, KERN_ERR, DRM_UT_NONE, __func__, " *ERROR*",\
> - fmt, ##__VA_ARGS__)
> + dev_err(dev, _DRM_FMT_FUNC_PREFIX "*ERROR*" fmt, __func__, \
> + ##__VA_ARGS__)
> #define DRM_ERROR(fmt, ...) \
> - drm_printk(KERN_ERR, DRM_UT_NONE, fmt, ##__VA_ARGS__)
> + pr_err(_DRM_FMT_FUNC_PREFIX "*ERROR*" fmt, __func__, \
> + ##__VA_ARGS__)
>
> /**
> * Rate limited error output. Like DRM_ERROR() but won't flood the log.
> @@ -193,21 +191,14 @@ struct dma_buf_attachment;
> if (__ratelimit(&_rs)) \
> DRM_DEV_ERROR(dev, fmt, ##__VA_ARGS__); \
> })
> -#define DRM_ERROR_RATELIMITED(fmt, ...) \
> - DRM_DEV_ERROR_RATELIMITED(NULL, fmt, ##__VA_ARGS__)
> +#define DRM_ERROR_RATELIMITED(fmt, args...) \
> + DRM_DEV_ERROR_RATELIMITED(NULL, fmt, ##args)
>
> -#define DRM_DEV_INFO(dev, fmt, ...) \
> - drm_dev_printk(dev, KERN_INFO, DRM_UT_NONE, __func__, "", fmt, \
> - ##__VA_ARGS__)
> +#define DRM_DEV_INFO(dev, fmt, args...) \
> + dev_info(dev, _DRM_FMT_FUNC_PREFIX fmt, __func__, ##args)
>
> -#define DRM_DEV_INFO_ONCE(dev, fmt, ...) \
> -({ \
> - static bool __print_once __read_mostly; \
> - if (!__print_once) { \
> - __print_once = true; \
> - DRM_DEV_INFO(dev, fmt, ##__VA_ARGS__); \
> - } \
> -})
> +#define DRM_DEV_INFO_ONCE(dev, fmt, args...) \
> + dev_info_once(dev, _DRM_FMT_FUNC_PREFIX fmt, __func__, ##args)
>
> /**
> * Debug output.
> @@ -215,50 +206,104 @@ struct dma_buf_attachment;
> * \param fmt printf() like format string.
> * \param arg arguments
> */
> +
> +#if defined(CONFIG_DYNAMIC_DEBUG)
> +/* We don't use pr_debug and dev_dbg directly since we want to
> + * maintain format compatibility with non-dynamic drm debug messages
> + */
> +#define _DRM_DYNAMIC_DEV_DEBUG(dev, fmt, args...) \
> +({ \
> + DEFINE_DYNAMIC_DEBUG_METADATA(descriptor, fmt); \
> + if (DYNAMIC_DEBUG_BRANCH(descriptor)) \
> + dev_printk(KERN_DEBUG, dev, fmt, ##args); \
> +})
> +#define _DRM_DYNAMIC_DEBUG(fmt, args...) \
> +({ \
> + DEFINE_DYNAMIC_DEBUG_METADATA(descriptor, fmt); \
> + if (DYNAMIC_DEBUG_BRANCH(descriptor)) \
> + printk(KERN_DEBUG fmt, ##args); \
> +})
> +#else
> +#define _DRM_DYNAMIC_DEV_DEBUG(dev, fmt, args...) \
> + no_printk(fmt, ##args)
> +#define _DRM_DYNAMIC_DEBUG(fmt, args...) \
> + no_printk(fmt, ##args)
> +#endif
> +
> +/* The conditional use of pr_debug/dev_dbg here allows us to take
> + * advantage of the kernel's dynamic debug feature by default (ref
> + * Documentation/dynamic-debug-howto.txt) while maintaining
> + * compatibility with using drm.drm_debug to turn on sets of messages
> + *
> + * Note: pr_debug and dev_dbg can't be called by a wrapper function
> + * otherwise they can't track the __FILE__, __func__ and __LINE__
> + * where they are called.
> + */
> +#define _DRM_DEV_DEBUG(dev, category, fmt, args...) \
> +({ \
> + if (unlikely(drm_debug & category)) { \
> + dev_printk(KERN_DEBUG, dev, _DRM_FMT_FUNC_PREFIX fmt, \
> + __func__, ##args); \
> + } else { \
> + _DRM_DYNAMIC_DEV_DEBUG(dev, _DRM_FMT_FUNC_PREFIX fmt, \
> + __func__, ##args); \
> + } \
> +})
> +#define _DRM_DEBUG(category, fmt, args...) \
> +({ \
> + if (unlikely(drm_debug & category)) { \
> + printk(KERN_DEBUG _DRM_FMT_FUNC_PREFIX fmt, \
> + __func__, ##args); \
> + } else \
> + _DRM_DYNAMIC_DEBUG(_DRM_FMT_FUNC_PREFIX fmt, \
> + __func__, ##args); \
> +})
> +
> #define DRM_DEV_DEBUG(dev, fmt, args...) \
> - drm_dev_printk(dev, KERN_DEBUG, DRM_UT_CORE, __func__, "", fmt, \
> - ##args)
> -#define DRM_DEBUG(fmt, ...) \
> - drm_printk(KERN_DEBUG, DRM_UT_CORE, fmt, ##__VA_ARGS__)
> + _DRM_DEV_DEBUG(dev, DRM_UT_CORE, fmt, ##args)
> +#define DRM_DEBUG(fmt, args...) \
> + _DRM_DEBUG(DRM_UT_CORE, fmt, ##args)
>
> #define DRM_DEV_DEBUG_DRIVER(dev, fmt, args...) \
> - drm_dev_printk(dev, KERN_DEBUG, DRM_UT_DRIVER, __func__, "", \
> - fmt, ##args)
> -#define DRM_DEBUG_DRIVER(fmt, ...) \
> - drm_printk(KERN_DEBUG, DRM_UT_DRIVER, fmt, ##__VA_ARGS__)
> + _DRM_DEV_DEBUG(dev, DRM_UT_DRIVER, fmt, ##args)
> +#define DRM_DEBUG_DRIVER(fmt, args...) \
> + _DRM_DEBUG(DRM_UT_DRIVER, fmt, ##args)
>
> #define DRM_DEV_DEBUG_KMS(dev, fmt, args...) \
> - drm_dev_printk(dev, KERN_DEBUG, DRM_UT_KMS, __func__, "", fmt, \
> - ##args)
> -#define DRM_DEBUG_KMS(fmt, ...) \
> - drm_printk(KERN_DEBUG, DRM_UT_KMS, fmt, ##__VA_ARGS__)
> + _DRM_DEV_DEBUG(dev, DRM_UT_KMS, fmt, ##args)
> +#define DRM_DEBUG_KMS(fmt, args...) \
> + _DRM_DEBUG(DRM_UT_KMS, fmt, ##args)
>
> #define DRM_DEV_DEBUG_PRIME(dev, fmt, args...) \
> - drm_dev_printk(dev, KERN_DEBUG, DRM_UT_PRIME, __func__, "", \
> - fmt, ##args)
> -#define DRM_DEBUG_PRIME(fmt, ...) \
> - drm_printk(KERN_DEBUG, DRM_UT_PRIME, fmt, ##__VA_ARGS__)
> + _DRM_DEV_DEBUG(dev, DRM_UT_PRIME, fmt, ##args)
> +#define DRM_DEBUG_PRIME(fmt, args...) \
> + _DRM_DEBUG(DRM_UT_PRIME, fmt, ##args)
>
> #define DRM_DEV_DEBUG_ATOMIC(dev, fmt, args...) \
> - drm_dev_printk(dev, KERN_DEBUG, DRM_UT_ATOMIC, __func__, "", \
> - fmt, ##args)
> -#define DRM_DEBUG_ATOMIC(fmt, ...) \
> - drm_printk(KERN_DEBUG, DRM_UT_ATOMIC, fmt, ##__VA_ARGS__)
> + _DRM_DEV_DEBUG(dev, DRM_UT_ATOMIC, fmt, ##args)
> +#define DRM_DEBUG_ATOMIC(fmt, args...) \
> + _DRM_DEBUG(DRM_UT_ATOMIC, fmt, ##args)
>
> #define DRM_DEV_DEBUG_VBL(dev, fmt, args...) \
> - drm_dev_printk(dev, KERN_DEBUG, DRM_UT_VBL, __func__, "", fmt, \
> - ##args)
> -#define DRM_DEBUG_VBL(fmt, ...) \
> - drm_printk(KERN_DEBUG, DRM_UT_VBL, fmt, ##__VA_ARGS__)
> + _DRM_DEV_DEBUG(dev, DRM_UT_VBL, fmt, ##args)
> +#define DRM_DEBUG_VBL(fmt, args...) \
> + _DRM_DEBUG(DRM_UT_VBL, fmt, ##args)
>
> -#define _DRM_DEV_DEFINE_DEBUG_RATELIMITED(dev, level, fmt, args...) \
> +#define _DRM_DEV_DEFINE_DEBUG_RATELIMITED(dev, category, fmt, args...) \
> +({ \
> + static DEFINE_RATELIMIT_STATE(_rs, \
> + DEFAULT_RATELIMIT_INTERVAL, \
> + DEFAULT_RATELIMIT_BURST); \
> + if (__ratelimit(&_rs)) \
> + _DRM_DEV_DEBUG(dev, DRM_UT_ ## category, fmt, ##args); \
> +})
> +#define _DRM_DEFINE_DEBUG_RATELIMITED(category, fmt, args...) \
> ({ \
> static DEFINE_RATELIMIT_STATE(_rs, \
> DEFAULT_RATELIMIT_INTERVAL, \
> DEFAULT_RATELIMIT_BURST); \
> if (__ratelimit(&_rs)) \
> - drm_dev_printk(dev, KERN_DEBUG, DRM_UT_ ## level, \
> - __func__, "", fmt, ##args); \
> + _DRM_DEBUG(DRM_UT_ ## category, fmt, ##args); \
> })
>
> /**
> @@ -268,21 +313,24 @@ struct dma_buf_attachment;
> * \param arg arguments
> */
> #define DRM_DEV_DEBUG_RATELIMITED(dev, fmt, args...) \
> - DEV__DRM_DEFINE_DEBUG_RATELIMITED(dev, CORE, fmt, ##args)
> + _DRM_DEFINE_DEBUG_RATELIMITED(dev, CORE, fmt, ##args)
> #define DRM_DEBUG_RATELIMITED(fmt, args...) \
> - DRM_DEV_DEBUG_RATELIMITED(NULL, fmt, ##args)
> + _DRM_DEFINE_DEBUG_RATELIMITED(CORE, fmt, ##args)
> +
> #define DRM_DEV_DEBUG_DRIVER_RATELIMITED(dev, fmt, args...) \
> _DRM_DEV_DEFINE_DEBUG_RATELIMITED(dev, DRIVER, fmt, ##args)
> #define DRM_DEBUG_DRIVER_RATELIMITED(fmt, args...) \
> - DRM_DEV_DEBUG_DRIVER_RATELIMITED(NULL, fmt, ##args)
> + _DRM_DEV_DEFINE_DEBUG_RATELIMITED(DRIVER, fmt, ##args)
> +
> #define DRM_DEV_DEBUG_KMS_RATELIMITED(dev, fmt, args...) \
> _DRM_DEV_DEFINE_DEBUG_RATELIMITED(dev, KMS, fmt, ##args)
> #define DRM_DEBUG_KMS_RATELIMITED(fmt, args...) \
> - DRM_DEV_DEBUG_KMS_RATELIMITED(NULL, fmt, ##args)
> + _DRM_DEFINE_DEBUG_RATELIMITED(KMS, fmt, ##args)
> +
> #define DRM_DEV_DEBUG_PRIME_RATELIMITED(dev, fmt, args...) \
> _DRM_DEV_DEFINE_DEBUG_RATELIMITED(dev, PRIME, fmt, ##args)
> #define DRM_DEBUG_PRIME_RATELIMITED(fmt, args...) \
> - DRM_DEV_DEBUG_PRIME_RATELIMITED(NULL, fmt, ##args)
> + _DRM_DEFINE_DEBUG_RATELIMITED(PRIME, fmt, ##args)
>
> /* Format strings and argument splitters to simplify printing
> * various "complex" objects
Since I brought up some changes for the debug stuff itself, would it make
sense to split that from the general macro rework for all the non-debug
output, and merge that first?
Another thing to look into: I think it'd be good to move all the print
definitions into drm_print.[hc], since drmP.h is a mess, and drm_drv.c not
really the right place. That would then also allow us to easily document
all the variants, and put something like the intro message for this commit
into the overview DOC: section.
-Daniel
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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