This is the mail archive of the
systemtap@sourceware.org
mailing list for the systemtap project.
Re: [RFC PATCH] Kernel Tracepoints (update)
- From: Mathieu Desnoyers <mathieu dot desnoyers at polymtl dot ca>
- To: Masami Hiramatsu <mhiramat at redhat dot com>
- Cc: KOSAKI Motohiro <kosaki dot motohiro at jp dot fujitsu dot com>, Takashi Nishiie <t-nishiie at np dot css dot fujitsu dot com>, 'Alexey Dobriyan' <adobriyan at gmail dot com>, 'Peter Zijlstra' <peterz at infradead dot org>, 'Steven Rostedt' <rostedt at goodmis dot org>, "'Frank Ch. Eigler'" <fche at redhat dot com>, 'Ingo Molnar' <mingo at elte dot hu>, 'LKML' <linux-kernel at vger dot kernel dot org>, 'systemtap-ml' <systemtap at sources dot redhat dot com>, 'Hideo AOKI' <haoki at redhat dot com>
- Date: Thu, 3 Jul 2008 14:18:39 -0400
- Subject: Re: [RFC PATCH] Kernel Tracepoints (update)
- References: <007601c8d5ca$18fa0e10$4aee2a30$@css.fujitsu.com> <48611B03.1000003@redhat.com> <20080625011951.D83E.KOSAKI.MOTOHIRO@jp.fujitsu.com> <48612879.5090809@redhat.com> <20080625235214.GA14249@Krystal> <486403F0.4020801@redhat.com> <20080627133622.GA15210@Krystal> <486CEFDB.7070508@redhat.com>
Hi Masami,
I am thinking about removing the private_data, because such declaration
won't work :
DEFINE_TRACE(kernel_irq_exit,
TPPROTO(void),
TPARGS());
because the arguments become :
(void *private_data, void)
Any better idea ?
Mathieu
* Masami Hiramatsu (mhiramat@redhat.com) wrote:
> Hi Mathieu,
>
> I found a bug.
> Mathieu Desnoyers wrote:
> [...]
>
> > +/*
> > + * Remove the tracepoint from the tracepoint hash table. Must be called with
> > + * mutex_lock held.
> > + */
> > +static int remove_tracepoint(const char *name)
> > +{
> > + struct hlist_head *head;
> > + struct hlist_node *node;
> > + struct tracepoint_entry *e;
> > + int found = 0;
> > + size_t len = strlen(name) + 1;
> > + u32 hash = jhash(name, len-1, 0);
> > +
> > + head = &tracepoint_table[hash & ((1 << TRACEPOINT_HASH_BITS)-1)];
> > + hlist_for_each_entry(e, node, head, hlist) {
> > + if (!strcmp(name, e->name)) {
> > + found = 1;
> > + break;
> > + }
> > + }
> > + if (!found)
> > + return -ENOENT;
>
> before removing, you have to ensure refcount == 0. So,
> if (e->refcount != 0)
> return -EBUSY;
>
> > + hlist_del(&e->hlist);
> > + /* Make sure the call_rcu has been executed */
> > + if (e->rcu_pending)
> > + rcu_barrier();
> > + kfree(e);
> > + return 0;
> > +}
>
> Thank you,
>
> --
> Masami Hiramatsu
>
> Software Engineer
> Hitachi Computer Products (America) Inc.
> Software Solutions Division
>
> e-mail: mhiramat@redhat.com
>
--
Mathieu Desnoyers
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68