Messages in this thread | | | Date | Fri, 25 Jan 2013 09:38:51 -0500 | From | Mathieu Desnoyers <> | Subject | Re: [tracepoint] cargo-culting considered harmful... |
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* Steven Rostedt (rostedt@goodmis.org) wrote: > On Wed, Jan 23, 2013 at 10:55:24PM +0000, Al Viro wrote: > > In samples/tracepoints/tracepoint-probe-sample.c: > > /* > > * Here the caller only guarantees locking for struct file and struct inode. > > * Locking must therefore be done in the probe to use the dentry. > > */ > > static void probe_subsys_event(void *ignore, > > struct inode *inode, struct file *file) > > { > > path_get(&file->f_path); > > dget(file->f_path.dentry); > > printk(KERN_INFO "Event is encountered with filename %s\n", > > file->f_path.dentry->d_name.name); > > dput(file->f_path.dentry); > > path_put(&file->f_path); > > } > > > > note that > > * file->f_path is already pinned down by open(), path_get() does not > > provide anything extra. > > * file->f_path.dentry is already pinned by open() *and* path_get() > > just above that dget(). > > * ->d_name.name *IS* *NOT* *PROTECTED* by pinning dentry down, > > whether it's done once or thrice. > > > > I do realize that it's just an example, but perhaps we should rename that > > file to match the contents? The only question is whether it should be > > git mv samples/tracepoints/{tracepoint-probe-sample,cargo-cult}.c > > or git mv samples cargo-cult... > > I wonder if we should just remove the samples/tracepoints/ all together. > The tracepoint code is now only used internally by the trace_event code, > and there should not be any users of tracepoints directly.
Yep, I'd be OK with removing this example, since now all users are expected to user TRACE_EVENT(), which is built on top of tracepoints.
Thanks,
Mathieu
-- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com
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