Re: [PATCH rcu 10/11] srcu: Add FORCE_NEED_SRCU_NMI_SAFE Kconfig for testing
From: Geert Uytterhoeven <geert@linux-m68k.org>
Date: 2025-03-25 08:12:01
Also in:
linux-doc, linux-kselftest, lkml, rcu
Hi Boqun, Paul, On Wed, 19 Feb 2025 at 16:44, Boqun Feng [off-list ref] wrote:
From: "Paul E. McKenney" <paulmck@kernel.org> The srcu_read_lock_nmisafe() and srcu_read_unlock_nmisafe() functions map to __srcu_read_lock() and __srcu_read_unlock() on systems like x86 that have NMI-safe this_cpu_inc() operations. This makes the underlying __srcu_read_lock_nmisafe() and __srcu_read_unlock_nmisafe() functions difficult to test on (for example) x86 systems, allowing bugs to creep in. This commit therefore creates a FORCE_NEED_SRCU_NMI_SAFE Kconfig that forces those underlying functions to be used even on systems where they are not needed, thus providing better testing coverage. Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Boqun Feng <redacted>
Thanks for your patch, which is now commit 536e8b9b80bc7a0a ("srcu:
Add FORCE_NEED_SRCU_NMI_SAFE Kconfig for testing") in linus/master
quoted hunk ↗ jump to hunk
--- a/kernel/rcu/Kconfig +++ b/kernel/rcu/Kconfig@@ -65,6 +65,17 @@ config TREE_SRCU help This option selects the full-fledged version of SRCU. +config FORCE_NEED_SRCU_NMI_SAFE + bool "Force selection of NEED_SRCU_NMI_SAFE"
What am I supposed to answer here? "n" I guess. What about distro and allmodconfig kernels?
+ depends on !TINY_SRCU + select NEED_SRCU_NMI_SAFE + default n + help + This option forces selection of the NEED_SRCU_NMI_SAFE + Kconfig option, allowing testing of srcu_read_lock_nmisafe() + and srcu_read_unlock_nmisafe() on architectures (like x86) + that select the ARCH_HAS_NMI_SAFE_THIS_CPU_OPS Kconfig option.
Perhaps this should depend on ARCH_HAS_NMI_SAFE_THIS_CPU_OPS?
+
config NEED_SRCU_NMI_SAFE
def_bool HAVE_NMI && !ARCH_HAS_NMI_SAFE_THIS_CPU_OPS && !TINY_SRCU
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds