Sean Paul seanp...@chromium.org proposed, in https://patchwork.freedesktop.org/series/78133/ drm/trace: Mirror DRM debug logs to tracefs
The problem with the approach is that its built upon splitting drm_debug_enabled() into syslog & trace flavors, which clashes rather profoundly with the strategy of obsoleting it using dyndbg. Instead, this puts the print-to-trace decision after the is-it-enabled test (which is a noop), so it has near zero additional cost. This is preliminary, Proof-of-Concept, and about 2 hrs old. But its surprisingly simple: - add a new struct _ddebug member: (*aux_print)(char *format, ...) - add a new S/special flag to check !!aux_print - if S, invoke the function to handle the prepared vaf It intrinsically allows any number of alternate printf-ish consumers, but only 1 active per callsite. I have another patchset that eliminates some of the data redundancies like this, it can be extended. It may also prove to be a generic way to implement the netdev & ibdev variants of __dynamic_pr_debug. It just needs a mechanism to set the per-callsite pointer to a printf-ish function to consume the pr_debug output, a tighter/better function prototype, and a wrapper on drm_trace_printf to bundle up the args and comport with the prototype, which can evolve to suit this 1st client. it is on top of: https://patchwork.freedesktop.org/series/92544/ (v4 on lkml, v2 in patchwork) Signed-off-by: Jim Cromie <jim.cro...@gmail.com> --- include/linux/dynamic_debug.h | 7 ++++++- lib/dynamic_debug.c | 22 +++++++++++++++++++--- 2 files changed, 25 insertions(+), 4 deletions(-) diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h index 677ad176b167..0d068e8ed7aa 100644 --- a/include/linux/dynamic_debug.h +++ b/include/linux/dynamic_debug.h @@ -22,6 +22,7 @@ struct _ddebug { const char *function; const char *filename; const char *format; + int (*aux_print)(char *, void *, void *); unsigned int lineno:18; /* * The flags field controls the behaviour at the callsite. @@ -29,7 +30,11 @@ struct _ddebug { * writes commands to <debugfs>/dynamic_debug/control */ #define _DPRINTK_FLAGS_NONE 0 -#define _DPRINTK_FLAGS_PRINT (1<<0) /* printk() a message using the format */ +#define _DPRINTK_FLAGS_PRINT (1<<0) /* printk() a message */ +#define _DPRINTK_FLAGS_PRINT_AUX (1<<5) /* call (*aux_print) */ + +#define _DPRINTK_ENABLED (_DPRINTK_FLAGS_PRINT | _DPRINTK_FLAGS_PRINT_AUX) + #define _DPRINTK_FLAGS_INCL_MODNAME (1<<1) #define _DPRINTK_FLAGS_INCL_FUNCNAME (1<<2) #define _DPRINTK_FLAGS_INCL_LINENO (1<<3) diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c index 045e1cf92c44..7bbdedabe6f1 100644 --- a/lib/dynamic_debug.c +++ b/lib/dynamic_debug.c @@ -85,6 +85,7 @@ static inline const char *trim_prefix(const char *path) static struct { unsigned flag:8; char opt_char; } opt_array[] = { { _DPRINTK_FLAGS_PRINT, 'p' }, + { _DPRINTK_FLAGS_PRINT_AUX, 'S' }, { _DPRINTK_FLAGS_INCL_MODNAME, 'm' }, { _DPRINTK_FLAGS_INCL_FUNCNAME, 'f' }, { _DPRINTK_FLAGS_INCL_LINENO, 'l' }, @@ -206,10 +207,10 @@ static int ddebug_change(const struct ddebug_query *query, if (newflags == dp->flags) continue; #ifdef CONFIG_JUMP_LABEL - if (dp->flags & _DPRINTK_FLAGS_PRINT) { - if (!(modifiers->flags & _DPRINTK_FLAGS_PRINT)) + if (dp->flags & _DPRINTK_ENABLED) { + if (!(modifiers->flags & _DPRINTK_ENABLED)) static_branch_disable(&dp->key.dd_key_true); - } else if (modifiers->flags & _DPRINTK_FLAGS_PRINT) + } else if (modifiers->flags & _DPRINTK_ENABLED) static_branch_enable(&dp->key.dd_key_true); #endif dp->flags = newflags; @@ -639,6 +640,21 @@ void __dynamic_pr_debug(struct _ddebug *descriptor, const char *fmt, ...) printk(KERN_DEBUG "%s%pV", dynamic_emit_prefix(descriptor, buf), &vaf); + if (descriptor->flags & _DPRINTK_FLAGS_PRINT_AUX) { + /* our model: + drm_trace_printf("%s%s[" DRM_NAME ":%ps] %pV", + dev ? dev_name(dev) : "", dev ? " " : "", + __builtin_return_address(0), &vaf); + */ + pr_info("reached check aux\n"); + + if (descriptor->aux_channel) { + pr_info("calling aux\n"); + (*descriptor->aux_channel) + ("%s[DRM_mumble :%ps] %pV", buf, + __builtin_return_address(0), &vaf); + } + } va_end(args); } EXPORT_SYMBOL(__dynamic_pr_debug); -- 2.31.1
