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From: Jim Cromie <jim.cromie@gmail.com>
To: jbaron@akamai.com, gregkh@linuxfoundation.org,
	daniel.vetter@ffwll.ch, seanpaul@chromium.org,
	robdclark@gmail.com, linux-kernel@vger.kernel.org,
	dri-devel@lists.freedesktop.org, amd-gfx@lists.freedesktop.org,
	intel-gvt-dev@lists.freedesktop.org,
	intel-gfx@lists.freedesktop.org
Cc: Jim Cromie <jim.cromie@gmail.com>
Subject: [PATCH 11/13] drm_print: prefer bare printk KERN_DEBUG on generic fn
Date: Tue,  1 Mar 2022 09:46:27 -0700	[thread overview]
Message-ID: <20220301164629.3814634-12-jim.cromie@gmail.com> (raw)
In-Reply-To: <20220301164629.3814634-1-jim.cromie@gmail.com>

drm_print.c calls pr_debug() just once, from __drm_printfn_debug(),
which is a generic/service fn.  The callsite is compile-time enabled
by DEBUG in both DYNAMIC_DEBUG=y/n builds.

For dyndbg builds, reverting this callsite back to bare printk is
correcting a few anti-features:

1- callsite is generic, serves multiple drm users.
   its hardwired on currently
   could accidentally: #> echo -p > /proc/dynamic_debug/control

2- optional "decorations" by dyndbg are unhelpful/misleading
   they describe only the generic site, not end users

IOW, 1,2 are unhelpful at best, and possibly confusing.

reverting yields a nominal data and text shrink:

   text    data     bss     dec     hex filename
 462583   36604   54592 553779   87333 /lib/modules/5.16.0-rc4-lm1-00008-ged3eac8ceeea/kernel/drivers/gpu/drm/drm.ko
 462515   36532   54592 553639   872a7 /lib/modules/5.16.0-rc4-lm1-00009-g6ce0b88d2539-dirty/kernel/drivers/gpu/drm/drm.ko

NB: this was noticed using _drm_debug_enabled(), added earlier.

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
 drivers/gpu/drm/drm_print.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/drm_print.c b/drivers/gpu/drm/drm_print.c
index 92e6e18026da..24c57b92dc69 100644
--- a/drivers/gpu/drm/drm_print.c
+++ b/drivers/gpu/drm/drm_print.c
@@ -23,8 +23,6 @@
  * Rob Clark <robdclark@gmail.com>
  */
 
-#define DEBUG /* for pr_debug() */
-
 #include <linux/stdarg.h>
 
 #include <linux/io.h>
@@ -162,7 +160,8 @@ EXPORT_SYMBOL(__drm_printfn_info);
 
 void __drm_printfn_debug(struct drm_printer *p, struct va_format *vaf)
 {
-	pr_debug("%s %pV", p->prefix, vaf);
+	/* pr_debug callsite decorations are unhelpful here */
+	printk(KERN_DEBUG "%s %pV", p->prefix, vaf);
 }
 EXPORT_SYMBOL(__drm_printfn_debug);
 
-- 
2.35.1


  parent reply	other threads:[~2022-03-01 16:47 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-03-01 16:46 [PATCH 00/12] use dynamic-debug under drm.debug api Jim Cromie
2022-03-01 16:46 ` [PATCH 01/13] dyndbg: fix static_branch manipulation Jim Cromie
2022-03-01 16:46 ` [PATCH 02/13] dyndbg: add class_id field and query support Jim Cromie
2022-03-01 16:46 ` [PATCH 03/13] dyndbg: add DEFINE_DYNAMIC_DEBUG_CLASSBITS macro and callbacks Jim Cromie
2022-03-01 16:46 ` [PATCH 04/13] dyndbg: drop EXPORTed dynamic_debug_exec_queries Jim Cromie
2022-03-01 16:46 ` [PATCH 05/13] dyndbg: improve change-info to have old and new Jim Cromie
2022-03-01 16:46 ` [PATCH 06/13] dyndbg: abstract dyndbg_site_is_printing Jim Cromie
2022-03-01 16:46 ` [PATCH 07/13] drm_print: condense enum drm_debug_category Jim Cromie
2022-03-01 16:46 ` [PATCH 08/13] drm_print: interpose drm_*dbg with forwarding macros Jim Cromie
2022-03-01 16:46 ` [PATCH 09/13] drm_print: wrap drm_*_dbg in dyndbg jumplabel Jim Cromie
2022-03-01 16:46 ` [PATCH 10/13] drm_print: refine drm_debug_enabled for dyndbg+jump-label Jim Cromie
2022-03-01 16:46 ` Jim Cromie [this message]
2022-03-01 16:46 ` [PATCH 12/13] drm_print: add _ddebug desc to drm_*dbg prototypes Jim Cromie
2022-03-01 16:46 ` [PATCH 13/13] drm_print: use DEFINE_DYNAMIC_DEBUG_CLASSBITS for drm.debug Jim Cromie
  -- strict thread matches above, loose matches on Subject: below --
2022-02-17  3:48 [PATCH 00/12] use dynamic-debug under drm.debug api Jim Cromie
2022-02-17  3:48 ` [PATCH 11/13] drm_print: prefer bare printk KERN_DEBUG on generic fn Jim Cromie

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