On Tue, Jun 24, 2025 at 12:57:06PM +0200, Amir Goldstein wrote: > On Tue, Jun 24, 2025 at 10:29 AM Christian Brauner <brauner@xxxxxxxxxx> wrote: > > > > Mark the range from -10000 to -40000 as a range reserved for special > > in-kernel values. Move the PIDFD_SELF_*/PIDFD_THREAD_* sentinels over so > > all the special values are in one place. > > > > Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx> > > --- > > include/uapi/linux/fcntl.h | 16 ++++++++++++++++ > > include/uapi/linux/pidfd.h | 15 --------------- > > tools/testing/selftests/pidfd/pidfd.h | 2 +- > > 3 files changed, 17 insertions(+), 16 deletions(-) > > > > diff --git a/include/uapi/linux/fcntl.h b/include/uapi/linux/fcntl.h > > index a15ac2fa4b20..ba4a698d2f33 100644 > > --- a/include/uapi/linux/fcntl.h > > +++ b/include/uapi/linux/fcntl.h > > @@ -90,10 +90,26 @@ > > #define DN_ATTRIB 0x00000020 /* File changed attibutes */ > > #define DN_MULTISHOT 0x80000000 /* Don't remove notifier */ > > > > +/* Reserved kernel ranges [-100], [-10000, -40000]. */ > > #define AT_FDCWD -100 /* Special value for dirfd used to > > indicate openat should use the > > current working directory. */ > > > > +/* > > + * The concept of process and threads in userland and the kernel is a confusing > > + * one - within the kernel every thread is a 'task' with its own individual PID, > > + * however from userland's point of view threads are grouped by a single PID, > > + * which is that of the 'thread group leader', typically the first thread > > + * spawned. > > + * > > + * To cut the Gideon knot, for internal kernel usage, we refer to > > + * PIDFD_SELF_THREAD to refer to the current thread (or task from a kernel > > + * perspective), and PIDFD_SELF_THREAD_GROUP to refer to the current thread > > + * group leader... > > + */ > > +#define PIDFD_SELF_THREAD -10000 /* Current thread. */ > > +#define PIDFD_SELF_THREAD_GROUP -10001 /* Current thread group leader. */ > > + > > > > /* Generic flags for the *at(2) family of syscalls. */ > > > > diff --git a/include/uapi/linux/pidfd.h b/include/uapi/linux/pidfd.h > > index c27a4e238e4b..957db425d459 100644 > > --- a/include/uapi/linux/pidfd.h > > +++ b/include/uapi/linux/pidfd.h > > @@ -42,21 +42,6 @@ > > #define PIDFD_COREDUMP_USER (1U << 2) /* coredump was done as the user. */ > > #define PIDFD_COREDUMP_ROOT (1U << 3) /* coredump was done as root. */ > > > > -/* > > - * The concept of process and threads in userland and the kernel is a confusing > > - * one - within the kernel every thread is a 'task' with its own individual PID, > > - * however from userland's point of view threads are grouped by a single PID, > > - * which is that of the 'thread group leader', typically the first thread > > - * spawned. > > - * > > - * To cut the Gideon knot, for internal kernel usage, we refer to > > - * PIDFD_SELF_THREAD to refer to the current thread (or task from a kernel > > - * perspective), and PIDFD_SELF_THREAD_GROUP to refer to the current thread > > - * group leader... > > - */ > > -#define PIDFD_SELF_THREAD -10000 /* Current thread. */ > > -#define PIDFD_SELF_THREAD_GROUP -20000 /* Current thread group leader. */ > > - > > /* > > * ...and for userland we make life simpler - PIDFD_SELF refers to the current > > * thread, PIDFD_SELF_PROCESS refers to the process thread group leader. > > diff --git a/tools/testing/selftests/pidfd/pidfd.h b/tools/testing/selftests/pidfd/pidfd.h > > index efd74063126e..5dfeb1bdf399 100644 > > --- a/tools/testing/selftests/pidfd/pidfd.h > > +++ b/tools/testing/selftests/pidfd/pidfd.h > > @@ -56,7 +56,7 @@ > > #endif > > > > #ifndef PIDFD_SELF_THREAD_GROUP > > -#define PIDFD_SELF_THREAD_GROUP -20000 /* Current thread group leader. */ > > +#define PIDFD_SELF_THREAD_GROUP -10001 /* Current thread group leader. */ > > The commit message claims to move definions between header files, > but the value of PIDFD_SELF_THREAD_GROUP was changed. > > What am I missing? I've split that into two patches.
