| Message ID | 1476901693-8492-4-git-send-email-mark.rutland@arm.com |
|---|---|
| State | Superseded |
| Headers | show |
On Wed, Oct 19, 2016 at 07:28:13PM +0100, Mark Rutland wrote: > When CONFIG_THREAD_INFO_IN_TASK is selected, the current_thread_info() > macro relies on current having been defined prior to its use. However, > not all users of current_thread_info() include <asm/current.h>, and thus > current is not guaranteed to be defined. > > When CONFIG_THREAD_INFO_IN_TASK is not selected, it's possible that > get_current() / current are based upon current_thread_info(), and > <asm/current.h> includes <asm/thread_info.h>. Thus always including > <asm/current.h> would result in circular dependences on some platforms. > > To ensure both cases work, this patch includes <asm/current.h>, but only > when CONFIG_THREAD_INFO_IN_TASK is selected. > > Signed-off-by: Mark Rutland <mark.rutland@arm.com> > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Andy Lutomirski <luto@kernel.org> > Cc: Heiko Carstens <heiko.carstens@de.ibm.com> > Cc: Kees Cook <keescook@chromium.org> > --- > include/linux/thread_info.h | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h > index c75c6ab..ef1f4b0 100644 > --- a/include/linux/thread_info.h > +++ b/include/linux/thread_info.h > @@ -12,6 +12,7 @@ > #include <linux/restart_block.h> > > #ifdef CONFIG_THREAD_INFO_IN_TASK > +#include <asm/current.h> > #define current_thread_info() ((struct thread_info *)current) > #endif FWIW: Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
On Thu, Oct 20, 2016 at 12:29:26PM +0200, Heiko Carstens wrote: > On Wed, Oct 19, 2016 at 07:28:13PM +0100, Mark Rutland wrote: > > When CONFIG_THREAD_INFO_IN_TASK is selected, the current_thread_info() > > macro relies on current having been defined prior to its use. However, > > not all users of current_thread_info() include <asm/current.h>, and thus > > current is not guaranteed to be defined. > > > > When CONFIG_THREAD_INFO_IN_TASK is not selected, it's possible that > > get_current() / current are based upon current_thread_info(), and > > <asm/current.h> includes <asm/thread_info.h>. Thus always including > > <asm/current.h> would result in circular dependences on some platforms. > > > > To ensure both cases work, this patch includes <asm/current.h>, but only > > when CONFIG_THREAD_INFO_IN_TASK is selected. > > > > Signed-off-by: Mark Rutland <mark.rutland@arm.com> > > Cc: Andrew Morton <akpm@linux-foundation.org> > > Cc: Andy Lutomirski <luto@kernel.org> > > Cc: Heiko Carstens <heiko.carstens@de.ibm.com> > > Cc: Kees Cook <keescook@chromium.org> > > --- > > include/linux/thread_info.h | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h > > index c75c6ab..ef1f4b0 100644 > > --- a/include/linux/thread_info.h > > +++ b/include/linux/thread_info.h > > @@ -12,6 +12,7 @@ > > #include <linux/restart_block.h> > > > > #ifdef CONFIG_THREAD_INFO_IN_TASK > > +#include <asm/current.h> > > #define current_thread_info() ((struct thread_info *)current) > > #endif > > FWIW: > Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com> Cheers! Would you be happy to do the same for patch 2? Once these have a couple more acks I'll drop these on a (hopefully) stable branch, tagged so that we can both use them as a base. Thanks, Mark.
On Wed, Oct 19, 2016 at 11:28 AM, Mark Rutland <mark.rutland@arm.com> wrote: > When CONFIG_THREAD_INFO_IN_TASK is selected, the current_thread_info() > macro relies on current having been defined prior to its use. However, > not all users of current_thread_info() include <asm/current.h>, and thus > current is not guaranteed to be defined. > > When CONFIG_THREAD_INFO_IN_TASK is not selected, it's possible that > get_current() / current are based upon current_thread_info(), and > <asm/current.h> includes <asm/thread_info.h>. Thus always including > <asm/current.h> would result in circular dependences on some platforms. > > To ensure both cases work, this patch includes <asm/current.h>, but only > when CONFIG_THREAD_INFO_IN_TASK is selected. Reviewed-by: Andy Lutomirski <luto@kernel.org> although it would be nice if you moved your description of why the include is conditional into a comment. --Andy
On Thu, Oct 27, 2016 at 04:13:49PM -0700, Andy Lutomirski wrote: > On Wed, Oct 19, 2016 at 11:28 AM, Mark Rutland <mark.rutland@arm.com> wrote: > > When CONFIG_THREAD_INFO_IN_TASK is selected, the current_thread_info() > > macro relies on current having been defined prior to its use. However, > > not all users of current_thread_info() include <asm/current.h>, and thus > > current is not guaranteed to be defined. > > > > When CONFIG_THREAD_INFO_IN_TASK is not selected, it's possible that > > get_current() / current are based upon current_thread_info(), and > > <asm/current.h> includes <asm/thread_info.h>. Thus always including > > <asm/current.h> would result in circular dependences on some platforms. > > > > To ensure both cases work, this patch includes <asm/current.h>, but only > > when CONFIG_THREAD_INFO_IN_TASK is selected. > > Reviewed-by: Andy Lutomirski <luto@kernel.org> Cheers! > although it would be nice if you moved your description of why the > include is conditional into a comment. Agreed. I've folded in the below: #ifdef CONFIG_THREAD_INFO_IN_TASK /* * For CONFIG_THREAD_INFO_IN_TASK kernels we need <asm/current.h> for the * definition of current, but for !CONFIG_THREAD_INFO_IN_TASK kernels, * including <asm/current.h> can cause a circular dependency on some platforms. */ #include <asm/current.h> #define current_thread_info() ((struct thread_info *)current) #endif Thanks, Mark.
diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h index c75c6ab..ef1f4b0 100644 --- a/include/linux/thread_info.h +++ b/include/linux/thread_info.h @@ -12,6 +12,7 @@ #include <linux/restart_block.h> #ifdef CONFIG_THREAD_INFO_IN_TASK +#include <asm/current.h> #define current_thread_info() ((struct thread_info *)current) #endif
When CONFIG_THREAD_INFO_IN_TASK is selected, the current_thread_info() macro relies on current having been defined prior to its use. However, not all users of current_thread_info() include <asm/current.h>, and thus current is not guaranteed to be defined. When CONFIG_THREAD_INFO_IN_TASK is not selected, it's possible that get_current() / current are based upon current_thread_info(), and <asm/current.h> includes <asm/thread_info.h>. Thus always including <asm/current.h> would result in circular dependences on some platforms. To ensure both cases work, this patch includes <asm/current.h>, but only when CONFIG_THREAD_INFO_IN_TASK is selected. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Kees Cook <keescook@chromium.org> --- include/linux/thread_info.h | 1 + 1 file changed, 1 insertion(+) -- 1.9.1