| Message ID | 20221019225846.2501109-8-paulmck@kernel.org (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 7f96735dfad2f425de8182d81c2ee8d0c3452921 |
| Headers | show |
| Series | NMI-safe SRCU readers for v6.2 | expand |
Am 20.10.22 um 00:58 schrieb Paul E. McKenney: > The s390 architecture uses either a cmpxchg loop (old systems) > or the laa add-to-memory instruction (new systems) to implement > this_cpu_add(), both of which are NMI safe. This means that the old > and more-efficient srcu_read_lock() may be used in NMI context, without > the need for srcu_read_lock_nmisafe(). Therefore, add the new Kconfig > option ARCH_HAS_NMI_SAFE_THIS_CPU_OPS to arch/arm64/Kconfig, which will s390 ? > cause NEED_SRCU_NMI_SAFE to be deselected, thus preserving the current > srcu_read_lock() behavior. > > Link: https://lore.kernel.org/all/20220910221947.171557773@linutronix.de/ > > Suggested-by: Neeraj Upadhyay <quic_neeraju@quicinc.com> > Suggested-by: Frederic Weisbecker <frederic@kernel.org> > Suggested-by: Boqun Feng <boqun.feng@gmail.com> > Signed-off-by: Paul E. McKenney <paulmck@kernel.org> > Cc: Heiko Carstens <hca@linux.ibm.com> > Cc: Vasily Gorbik <gor@linux.ibm.com> > Cc: Alexander Gordeev <agordeev@linux.ibm.com> > Cc: Christian Borntraeger <borntraeger@linux.ibm.com> > Cc: Sven Schnelle <svens@linux.ibm.com> > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: John Ogness <john.ogness@linutronix.de> > Cc: Petr Mladek <pmladek@suse.com> > Cc: <linux-s390@vger.kernel.org> > --- > arch/s390/Kconfig | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig > index 318fce77601d3..0acdfda332908 100644 > --- a/arch/s390/Kconfig > +++ b/arch/s390/Kconfig > @@ -73,6 +73,7 @@ config S390 > select ARCH_HAS_GIGANTIC_PAGE > select ARCH_HAS_KCOV > select ARCH_HAS_MEM_ENCRYPT > + select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS > select ARCH_HAS_PTE_SPECIAL > select ARCH_HAS_SCALED_CPUTIME > select ARCH_HAS_SET_MEMORY
On Thu, Oct 20, 2022 at 07:16:44AM +0200, Christian Borntraeger wrote: > > > Am 20.10.22 um 00:58 schrieb Paul E. McKenney: > > The s390 architecture uses either a cmpxchg loop (old systems) > > or the laa add-to-memory instruction (new systems) to implement > > this_cpu_add(), both of which are NMI safe. This means that the old > > and more-efficient srcu_read_lock() may be used in NMI context, without > > the need for srcu_read_lock_nmisafe(). Therefore, add the new Kconfig > > option ARCH_HAS_NMI_SAFE_THIS_CPU_OPS to arch/arm64/Kconfig, which will > s390 ? > > cause NEED_SRCU_NMI_SAFE to be deselected, thus preserving the current > > srcu_read_lock() behavior. > > > > Link: https://lore.kernel.org/all/20220910221947.171557773@linutronix.de/ > > > > Suggested-by: Neeraj Upadhyay <quic_neeraju@quicinc.com> > > Suggested-by: Frederic Weisbecker <frederic@kernel.org> > > Suggested-by: Boqun Feng <boqun.feng@gmail.com> > > Signed-off-by: Paul E. McKenney <paulmck@kernel.org> ... > > --- > > arch/s390/Kconfig | 1 + > > 1 file changed, 1 insertion(+) Not sure what Christian was trying to say with his empty reply :) In any case: Acked-by: Heiko Carstens <hca@linux.ibm.com>
On Thu, Oct 20, 2022 at 09:23:49AM +0200, Heiko Carstens wrote: > On Thu, Oct 20, 2022 at 07:16:44AM +0200, Christian Borntraeger wrote: > > Am 20.10.22 um 00:58 schrieb Paul E. McKenney: > > > The s390 architecture uses either a cmpxchg loop (old systems) > > > or the laa add-to-memory instruction (new systems) to implement > > > this_cpu_add(), both of which are NMI safe. This means that the old > > > and more-efficient srcu_read_lock() may be used in NMI context, without > > > the need for srcu_read_lock_nmisafe(). Therefore, add the new Kconfig > > > option ARCH_HAS_NMI_SAFE_THIS_CPU_OPS to arch/arm64/Kconfig, which will > > s390 ? Ah, this typo is what Christian pointed out; missed that. > > > cause NEED_SRCU_NMI_SAFE to be deselected, thus preserving the current > > > srcu_read_lock() behavior. > > > > > > Link: https://lore.kernel.org/all/20220910221947.171557773@linutronix.de/ > > > > > > Suggested-by: Neeraj Upadhyay <quic_neeraju@quicinc.com> > > > Suggested-by: Frederic Weisbecker <frederic@kernel.org> > > > Suggested-by: Boqun Feng <boqun.feng@gmail.com> > > > Signed-off-by: Paul E. McKenney <paulmck@kernel.org> > ... > > > --- > > > arch/s390/Kconfig | 1 + > > > 1 file changed, 1 insertion(+) > > Not sure what Christian was trying to say with his empty reply :) > In any case: > Acked-by: Heiko Carstens <hca@linux.ibm.com>
On Thu, Oct 20, 2022 at 09:27:37AM +0200, Heiko Carstens wrote: > On Thu, Oct 20, 2022 at 09:23:49AM +0200, Heiko Carstens wrote: > > On Thu, Oct 20, 2022 at 07:16:44AM +0200, Christian Borntraeger wrote: > > > Am 20.10.22 um 00:58 schrieb Paul E. McKenney: > > > > The s390 architecture uses either a cmpxchg loop (old systems) > > > > or the laa add-to-memory instruction (new systems) to implement > > > > this_cpu_add(), both of which are NMI safe. This means that the old > > > > and more-efficient srcu_read_lock() may be used in NMI context, without > > > > the need for srcu_read_lock_nmisafe(). Therefore, add the new Kconfig > > > > option ARCH_HAS_NMI_SAFE_THIS_CPU_OPS to arch/arm64/Kconfig, which will > > > s390 ? > > Ah, this typo is what Christian pointed out; missed that. > > > > > cause NEED_SRCU_NMI_SAFE to be deselected, thus preserving the current > > > > srcu_read_lock() behavior. > > > > > > > > Link: https://lore.kernel.org/all/20220910221947.171557773@linutronix.de/ > > > > > > > > Suggested-by: Neeraj Upadhyay <quic_neeraju@quicinc.com> > > > > Suggested-by: Frederic Weisbecker <frederic@kernel.org> > > > > Suggested-by: Boqun Feng <boqun.feng@gmail.com> > > > > Signed-off-by: Paul E. McKenney <paulmck@kernel.org> > > ... > > > > --- > > > > arch/s390/Kconfig | 1 + > > > > 1 file changed, 1 insertion(+) > > > > Not sure what Christian was trying to say with his empty reply :) > > In any case: > > Acked-by: Heiko Carstens <hca@linux.ibm.com> I will apply the fix and the ack on my next rebase, thank you both! Thanx, Paul
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig index 318fce77601d3..0acdfda332908 100644 --- a/arch/s390/Kconfig +++ b/arch/s390/Kconfig @@ -73,6 +73,7 @@ config S390 select ARCH_HAS_GIGANTIC_PAGE select ARCH_HAS_KCOV select ARCH_HAS_MEM_ENCRYPT + select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS select ARCH_HAS_PTE_SPECIAL select ARCH_HAS_SCALED_CPUTIME select ARCH_HAS_SET_MEMORY
The s390 architecture uses either a cmpxchg loop (old systems) or the laa add-to-memory instruction (new systems) to implement this_cpu_add(), both of which are NMI safe. This means that the old and more-efficient srcu_read_lock() may be used in NMI context, without the need for srcu_read_lock_nmisafe(). Therefore, add the new Kconfig option ARCH_HAS_NMI_SAFE_THIS_CPU_OPS to arch/arm64/Kconfig, which will cause NEED_SRCU_NMI_SAFE to be deselected, thus preserving the current srcu_read_lock() behavior. Link: https://lore.kernel.org/all/20220910221947.171557773@linutronix.de/ Suggested-by: Neeraj Upadhyay <quic_neeraju@quicinc.com> Suggested-by: Frederic Weisbecker <frederic@kernel.org> Suggested-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Heiko Carstens <hca@linux.ibm.com> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Alexander Gordeev <agordeev@linux.ibm.com> Cc: Christian Borntraeger <borntraeger@linux.ibm.com> Cc: Sven Schnelle <svens@linux.ibm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: John Ogness <john.ogness@linutronix.de> Cc: Petr Mladek <pmladek@suse.com> Cc: <linux-s390@vger.kernel.org> --- arch/s390/Kconfig | 1 + 1 file changed, 1 insertion(+)