On Fri, Jan 07, 2022 at 06:29:26AM +0100, Jim Cromie wrote:
adds: dynamic_trace() uses trace_console() temporarily to issue printk:console event uses internal-ish __ftrace_trace_stack code: 4-context buffer stack, barriers per Steve
call it from new funcs: dynamic_printk() - print to both syslog/tracefs dynamic_dev_printk() - dev-print to both syslog/tracefs
These handle both _DPRINTK_FLAGS_PRINTK and _DPRINTK_FLAGS_TRACE cases, allowing to vsnprintf the message once and use it for both, skipping past the KERN_DEBUG character for tracing.
Finally, adjust the callers: __dynamic_{pr_debug,{,net,ib}dev_dbg}, replacing printk and dev_printk with the new funcs above.
The _DPRINTK_FLAGS_TRACE flag character s 'T', so the following finds all callsites enabled for tracing:
grep -P =p?T /proc/dynamic_debug/control
Enabling debug-to-tracefs is 2 steps:
# event enable echo 1 > /sys/kernel/tracing/events/dyndbg/enable # callsite enable echo module foo +T > /proc/dynamic_debug/control
This patch,~1,~2 are based upon: https://lore.kernel.org/lkml/20200825153338.17061-1-vincent.whitchurch@axis....
.. with simplification of temporarily reusing trace_console() rather than adding a new printk:dyndbg event. Soon, add 2 new events capturing the pr_debug & dev_dbg() args.
The example above does not match the code in this patch since the dyndbg:* events are only added in a later patch. Perhaps you could reorder this patch stack so that you don't use trace_console() in this patch just to replace it with the new events in the next patch?
CC: vincent.whitchurch@axis.com Signed-off-by: Jim Cromie jim.cromie@gmail.com
.../admin-guide/dynamic-debug-howto.rst | 1 + lib/dynamic_debug.c | 155 +++++++++++++++--- 2 files changed, 130 insertions(+), 26 deletions(-)
diff --git a/Documentation/admin-guide/dynamic-debug-howto.rst b/Documentation/admin-guide/dynamic-debug-howto.rst
[...]
@@ -723,29 +822,33 @@ void __dynamic_ibdev_dbg(struct _ddebug *descriptor, { struct va_format vaf; va_list args;
unsigned int flags;
va_start(args, fmt);
vaf.fmt = fmt; vaf.va = &args;
flags = descriptor->flags;
if (ibdev && ibdev->dev.parent) { char buf[PREFIX_SIZE] = "";
dev_printk_emit(LOGLEVEL_DEBUG, ibdev->dev.parent,"%s%s %s %s: %pV",dynamic_emit_prefix(descriptor, buf),dev_driver_string(ibdev->dev.parent),dev_name(ibdev->dev.parent),dev_name(&ibdev->dev),&vaf);
dynamic_dev_printk(flags, ibdev->dev.parent,"%s%s %s %s: %pV",dynamic_emit_prefix(descriptor, buf),dev_driver_string(ibdev->dev.parent),dev_name(ibdev->dev.parent),dev_name(&ibdev->dev),&vaf);
printk(KERN_DEBUG "%s: %pV", dev_name(&ibdev->dev), &vaf);
dynamic_printk(flags, KERN_DEBUG "%s%s: %pV",dev_name(&ibdev->dev), &vaf);
printk(KERN_DEBUG "(NULL ib_device): %pV", &vaf);
dynamic_printk(flags, KERN_DEBUG "(NULL ip_device): %pV",&vaf);
- va_end(args);
+va_end(args);
This looks like an unintentional whitespace change?