Messages in this thread Patch in this message | | | Date | Tue, 9 Jun 2020 14:38:29 -0700 | From | Eric Biggers <> | Subject | Re: [RFC][PATCH 7/7] sched: Replace rq::wake_list |
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On Tue, Jun 09, 2020 at 02:25:09PM -0700, Guenter Roeck wrote: > > > > Still occurring on Linus' tree. This needs to be fixed. (And not by removing > > support for randstruct; that's not a "fix"...) > > > > How about the hack below ? > > Guenter > > --- > diff --git a/include/linux/sched.h b/include/linux/sched.h > index c5d96e3e7fff..df1cbb04f9b3 100644 > --- a/include/linux/sched.h > +++ b/include/linux/sched.h > @@ -629,6 +629,15 @@ struct wake_q_node { > struct wake_q_node *next; > }; > > +/* > + * Hack around assumption that wake_entry_type follows wake_entry even with > + * CONFIG_GCC_PLUGIN_RANDSTRUCT=y. > + */ > +struct _wake_entry { > + struct llist_node wake_entry; > + unsigned int wake_entry_type; > +}; > + > struct task_struct { > #ifdef CONFIG_THREAD_INFO_IN_TASK > /* > @@ -653,8 +662,9 @@ struct task_struct { > unsigned int ptrace; > > #ifdef CONFIG_SMP > - struct llist_node wake_entry; > - unsigned int wake_entry_type; > + struct _wake_entry _we; > +#define wake_entry _we.wake_entry > +#define wake_entry_type _we.wake_entry_type > int on_cpu; > #ifdef CONFIG_THREAD_INFO_IN_TASK > /* Current CPU: */
Does the struct actually have to be named? How about:
diff --git a/include/linux/sched.h b/include/linux/sched.h index c5d96e3e7fff42..14ca25cda19150 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -653,8 +653,14 @@ struct task_struct { unsigned int ptrace; #ifdef CONFIG_SMP - struct llist_node wake_entry; - unsigned int wake_entry_type; + /* + * wake_entry_type must follow wake_entry, even when + * CONFIG_GCC_PLUGIN_RANDSTRUCT=y. + */ + struct { + struct llist_node wake_entry; + unsigned int wake_entry_type; + }; int on_cpu; #ifdef CONFIG_THREAD_INFO_IN_TASK /* Current CPU: */
However, it would be preferable to not rely on different structs sharing the same field order, but rather write proper C code that uses the same struct everywhere to encapsulate these 2 fields...
- Eric
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