Messages in this thread | | | Date | Fri, 14 Sep 2007 18:40:17 -0700 | From | Randy Dunlap <> | Subject | Re: [PATCH 1/2] Trace code and documentation |
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On Fri, 14 Sep 2007 18:08:40 -0700 Andrew Morton wrote:
> > Trace - Provides tracing primitives > > > > ... > > > > +config TRACE > > + bool "Trace setup and control" > > + select RELAY > > + select DEBUG_FS > > + help > > + This option provides support for the setup, teardown and control > > + of tracing channels from kernel code. It also provides trace > > + information and control to userspace via a set of debugfs control > > + files. If unsure, say N. > > + > > select is evil - you really want to avoid using it.
I checked when I reviewed(?) this patch. There are a few other places that select also (IIRC, the blktrace code does), but most of them use depends on.
> The problem is where you select a symbol whose dependencies aren't met. > Kconfig resolves this incompatibility by just not selecting the thing you > wanted, iirc. So your CONFIG_SYSFS=n, CONFIG_TRACE=y kernel won't build. > > > +/* > > + * Based on blktrace code, Copyright (C) 2006 Jens Axboe <axboe@suse.de> > > So can we migrate blktrace to using this?
> > +static ssize_t sub_size_read(struct file *filp, char __user *buffer, > > + size_t count, loff_t *ppos) > > +{ > > + struct trace_info *trace = filp->private_data; > > + char buf[32]; > > + > > + snprintf(buf, sizeof(buf), "%u\n", > > + (unsigned int)trace->rchan->subbuf_size); > > Use %tu to print a size_t, rather than the typecast.
Eh? Use %zu to print a size_t. Use %tu to print a ptrdiff_t.
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