On Sun, Oct 02, 2022 at 04:51:03PM -0700, Paul E. McKenney wrote: > On Mon, Oct 03, 2022 at 12:06:19AM +0200, Frederic Weisbecker wrote: > > On Thu, Sep 29, 2022 at 11:07:26AM -0700, Paul E. McKenney wrote: > > > This commit adds runtime checks to verify that a given srcu_struct uses > > > consistent NMI-safe (or not) read-side primitives on a per-CPU basis. > > > > > > Link: https://lore.kernel.org/all/20220910221947.171557773@xxxxxxxxxxxxx/ > > > > > > Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx> > > > Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > > > Cc: John Ogness <john.ogness@xxxxxxxxxxxxx> > > > Cc: Petr Mladek <pmladek@xxxxxxxx> > > > --- > > > include/linux/srcu.h | 4 ++-- > > > include/linux/srcutiny.h | 4 ++-- > > > include/linux/srcutree.h | 9 +++++++-- > > > kernel/rcu/srcutree.c | 38 ++++++++++++++++++++++++++++++++------ > > > 4 files changed, 43 insertions(+), 12 deletions(-) > > > > > > diff --git a/include/linux/srcu.h b/include/linux/srcu.h > > > index 2cc8321c0c86..565f60d57484 100644 > > > --- a/include/linux/srcu.h > > > +++ b/include/linux/srcu.h > > > @@ -180,7 +180,7 @@ static inline int srcu_read_lock_nmisafe(struct srcu_struct *ssp) __acquires(ssp > > > int retval; > > > > > > if (IS_ENABLED(CONFIG_NEED_SRCU_NMI_SAFE)) > > > - retval = __srcu_read_lock_nmisafe(ssp); > > > + retval = __srcu_read_lock_nmisafe(ssp, true); > > > else > > > retval = __srcu_read_lock(ssp); > > > > Shouldn't it be checked also when CONFIG_NEED_SRCU_NMI_SAFE=n ? > > You are asking why there is no "true" argument to __srcu_read_lock()? > That is because it checks unconditionally. It checks unconditionally but it always assumes not to be called as nmisafe. For example on x86/arm64/loongarch, the same ssp used with both srcu_read_lock() and srcu_read_lock_nmisafe() won't report an issue. But on powerpc it will. My point is that strong archs should warn as well on behalf of others, to detect mistakes early. Thanks.
