| Message ID | 165461827269.280167.7379263615545598958.stgit@devnote2 (mailing list archive) |
|---|---|
| State | Accepted |
| Delegated to: | BPF |
| Headers | show |
| Series | rethook: Reject getting a rethook if RCU is not watching | expand |
On Wed, 8 Jun 2022 01:11:12 +0900 "Masami Hiramatsu (Google)" <mhiramat@kernel.org> wrote: > From: Masami Hiramatsu (Google) <mhiramat@kernel.org> > > Since the rethook_recycle() will involve the call_rcu() for reclaiming > the rethook_instance, the rethook must be set up at the RCU available > context (non idle). This rethook_recycle() in the rethook trampoline > handler is inevitable, thus the RCU available check must be done before > setting the rethook trampoline. > > This adds a rcu_is_watching() check in the rethook_try_get() so that > it will return NULL if it is called when !rcu_is_watching(). > > Fixes: 54ecbe6f1ed5 ("rethook: Add a generic return hook") > Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> > --- > kernel/trace/rethook.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/kernel/trace/rethook.c b/kernel/trace/rethook.c > index b56833700d23..c69d82273ce7 100644 > --- a/kernel/trace/rethook.c > +++ b/kernel/trace/rethook.c > @@ -154,6 +154,15 @@ struct rethook_node *rethook_try_get(struct rethook *rh) > if (unlikely(!handler)) > return NULL; > > + /* > + * This expects the caller will set up a rethook on a function entry. > + * When the function returns, the rethook will eventually be reclaimed > + * or released in the rethook_recycle() with call_rcu(). > + * This means the caller must be run in the RCU-availabe context. > + */ > + if (unlikely(!rcu_is_watching())) > + return NULL; Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org> -- Steve > + > fn = freelist_try_get(&rh->pool); > if (!fn) > return NULL;
diff --git a/kernel/trace/rethook.c b/kernel/trace/rethook.c index b56833700d23..c69d82273ce7 100644 --- a/kernel/trace/rethook.c +++ b/kernel/trace/rethook.c @@ -154,6 +154,15 @@ struct rethook_node *rethook_try_get(struct rethook *rh) if (unlikely(!handler)) return NULL; + /* + * This expects the caller will set up a rethook on a function entry. + * When the function returns, the rethook will eventually be reclaimed + * or released in the rethook_recycle() with call_rcu(). + * This means the caller must be run in the RCU-availabe context. + */ + if (unlikely(!rcu_is_watching())) + return NULL; + fn = freelist_try_get(&rh->pool); if (!fn) return NULL;