[PATCH 02/24] preempt: Introduce HARDIRQ_DISABLE_BITS

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From: Boqun Feng <boqun@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: "Ingo Molnar" <mingo@kernel.org>, "Will Deacon" <will@kernel.org>,
	"Boqun Feng" <boqun@kernel.org>,
	"Waiman Long" <longman@redhat.com>, "Gary Guo" <gary@garyguo.net>,
	"Alice Ryhl" <aliceryhl@google.com>,
	"Lyude Paul" <lyude@redhat.com>,
	"Daniel Almeida" <daniel.almeida@collabora.com>,
	"Onur Özkan" <work@onurozkan.dev>,
	"Miguel Ojeda" <ojeda@kernel.org>,
	"Danilo Krummrich" <dakr@kernel.org>,
	linux-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org,
	"Boqun Feng" <boqun.feng@gmail.com>
Subject: [PATCH 02/24] preempt: Introduce HARDIRQ_DISABLE_BITS
Date: Fri, 31 Jul 2026 13:30:03 -0700	[thread overview]
Message-ID: <20260731203031.13679-3-boqun@kernel.org> (raw)
In-Reply-To: <20260731203031.13679-1-boqun@kernel.org>

From: Boqun Feng <boqun.feng@gmail.com>

In order to support preempt_disable()-like interrupt disabling, that is,
using part of preempt_count() to track interrupt disabling nested level,
change the preempt_count() layout to contain 8-bit HARDIRQ_DISABLE
count.

Signed-off-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Boqun Feng <boqun@kernel.org>
Link: https://patch.msgid.link/20260121223933.1568682-2-lyude@redhat.com
---
 include/linux/preempt.h                        | 16 +++++++++++-----
 tools/testing/selftests/bpf/bpf_experimental.h |  5 ++++-
 2 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/include/linux/preempt.h b/include/linux/preempt.h
index 586f96688325..e2d3079d3f5f 100644
--- a/include/linux/preempt.h
+++ b/include/linux/preempt.h
@@ -17,8 +17,9 @@
  *
  * - bits 0-7 are the preemption count (max preemption depth: 256)
  * - bits 8-15 are the softirq count (max # of softirqs: 256)
- * - bits 16-19 are the hardirq count (max # of hardirqs: 16)
- * - bit 20 is the NMI flag (no nesting count, tracked separately)
+ * - bits 16-23 are the hardirq disable count (max # of hardirq disable: 256)
+ * - bits 24-27 are the hardirq count (max # of hardirqs: 16)
+ * - bit 28 is the NMI flag (no nesting count, tracked separately)
  *
  * The hardirq count could in theory be the same as the number of
  * interrupts in the system, but we run all interrupt handlers with
@@ -31,29 +32,34 @@
  *
  *         PREEMPT_MASK:	0x000000ff
  *         SOFTIRQ_MASK:	0x0000ff00
- *         HARDIRQ_MASK:	0x000f0000
- *             NMI_MASK:	0x00100000
+ * HARDIRQ_DISABLE_MASK:	0x00ff0000
+ *         HARDIRQ_MASK:	0x0f000000
+ *             NMI_MASK:	0x10000000
  * PREEMPT_NEED_RESCHED:	0x80000000
  */
 #define PREEMPT_BITS	8
 #define SOFTIRQ_BITS	8
+#define HARDIRQ_DISABLE_BITS	8
 #define HARDIRQ_BITS	4
 #define NMI_BITS	1
 
 #define PREEMPT_SHIFT	0
 #define SOFTIRQ_SHIFT	(PREEMPT_SHIFT + PREEMPT_BITS)
-#define HARDIRQ_SHIFT	(SOFTIRQ_SHIFT + SOFTIRQ_BITS)
+#define HARDIRQ_DISABLE_SHIFT	(SOFTIRQ_SHIFT + SOFTIRQ_BITS)
+#define HARDIRQ_SHIFT	(HARDIRQ_DISABLE_SHIFT + HARDIRQ_DISABLE_BITS)
 #define NMI_SHIFT	(HARDIRQ_SHIFT + HARDIRQ_BITS)
 
 #define __IRQ_MASK(x)	((1UL << (x))-1)
 
 #define PREEMPT_MASK	(__IRQ_MASK(PREEMPT_BITS) << PREEMPT_SHIFT)
 #define SOFTIRQ_MASK	(__IRQ_MASK(SOFTIRQ_BITS) << SOFTIRQ_SHIFT)
+#define HARDIRQ_DISABLE_MASK	(__IRQ_MASK(HARDIRQ_DISABLE_BITS) << HARDIRQ_DISABLE_SHIFT)
 #define HARDIRQ_MASK	(__IRQ_MASK(HARDIRQ_BITS) << HARDIRQ_SHIFT)
 #define NMI_MASK	(__IRQ_MASK(NMI_BITS)     << NMI_SHIFT)
 
 #define PREEMPT_OFFSET	(1UL << PREEMPT_SHIFT)
 #define SOFTIRQ_OFFSET	(1UL << SOFTIRQ_SHIFT)
+#define HARDIRQ_DISABLE_OFFSET	(1UL << HARDIRQ_DISABLE_SHIFT)
 #define HARDIRQ_OFFSET	(1UL << HARDIRQ_SHIFT)
 #define NMI_OFFSET	(1UL << NMI_SHIFT)
 
diff --git a/tools/testing/selftests/bpf/bpf_experimental.h b/tools/testing/selftests/bpf/bpf_experimental.h
index e4e12001fce9..0159a3d365c8 100644
--- a/tools/testing/selftests/bpf/bpf_experimental.h
+++ b/tools/testing/selftests/bpf/bpf_experimental.h
@@ -366,17 +366,20 @@ extern int bpf_cgroup_read_xattr(struct cgroup *cgroup, const char *name__str,
 
 #define PREEMPT_BITS	8
 #define SOFTIRQ_BITS	8
+#define HARDIRQ_DISABLE_BITS	8
 #define HARDIRQ_BITS	4
 #define NMI_BITS	1
 
 #define PREEMPT_SHIFT	0
 #define SOFTIRQ_SHIFT	(PREEMPT_SHIFT + PREEMPT_BITS)
-#define HARDIRQ_SHIFT	(SOFTIRQ_SHIFT + SOFTIRQ_BITS)
+#define HARDIRQ_DISABLE_SHIFT	(SOFTIRQ_SHIFT + SOFTIRQ_BITS)
+#define HARDIRQ_SHIFT	(HARDIRQ_DISABLE_SHIFT + HARDIRQ_DISABLE_BITS)
 #define NMI_SHIFT	(HARDIRQ_SHIFT + HARDIRQ_BITS)
 
 #define __IRQ_MASK(x)	((1UL << (x))-1)
 
 #define SOFTIRQ_MASK	(__IRQ_MASK(SOFTIRQ_BITS) << SOFTIRQ_SHIFT)
+#define HARDIRQ_DISABLE_MASK	(__IRQ_MASK(HARDIRQ_DISABLE_BITS) << HARDIRQ_DISABLE_SHIFT)
 #define HARDIRQ_MASK	(__IRQ_MASK(HARDIRQ_BITS) << HARDIRQ_SHIFT)
 #define NMI_MASK	(__IRQ_MASK(NMI_BITS)     << NMI_SHIFT)
 
-- 
2.50.1 (Apple Git-155)

next prev parent reply	other threads:[~2026-07-31 20:30 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-07-31 20:30 [GIT PULL] [PATCH 00/24] Rust synchronization changes for v7.3 Boqun Feng
2026-07-31 20:30 ` [PATCH 01/24] preempt: Track NMI nesting to separate per-CPU counter Boqun Feng
2026-07-31 20:30 ` Boqun Feng [this message]
2026-07-31 20:30 ` [PATCH 03/24] preempt: Introduce __preempt_count_{sub, add}_return() Boqun Feng
2026-07-31 20:30 ` [PATCH 04/24] openrisc: Include <linux/cpumask.h> in smp.h Boqun Feng
2026-07-31 20:30 ` [PATCH 05/24] irq & spin_lock: Add counted interrupt disabling/enabling Boqun Feng
2026-07-31 20:30 ` [PATCH 06/24] irq: Add KUnit test for refcounted interrupt enable/disable Boqun Feng
2026-07-31 20:30 ` [PATCH 07/24] locking: Switch to _irq_{disable,enable}() variants in cleanup guards Boqun Feng
2026-07-31 20:30 ` [PATCH 08/24] sched: Remove the unused preempt_offset parameter of __cant_sleep() Boqun Feng
2026-07-31 20:30 ` [PATCH 09/24] sched: Avoid signed comparison of preempt_count() in __cant_migrate() Boqun Feng
2026-07-31 20:30 ` [PATCH 10/24] preempt: Introduce HAS_SEPARATE_PREEMPT_RESCHED_BITS Boqun Feng
2026-07-31 20:30 ` [PATCH 11/24] arm64: sched/preempt: Enable HAS_SEPARATE_PREEMPT_RESCHED_BITS Boqun Feng
2026-07-31 20:30 ` [PATCH 12/24] s390/preempt: " Boqun Feng
2026-07-31 20:30 ` [PATCH 13/24] irq: Optimize reschedule check in local_interrupt_enable() Boqun Feng
2026-07-31 20:30 ` [PATCH 14/24] rust: Introduce interrupt module Boqun Feng
2026-07-31 20:30 ` [PATCH 15/24] rust: helper: Add spin_{un,}lock_irq_{enable,disable}() helpers Boqun Feng
2026-07-31 20:30 ` [PATCH 16/24] rust: sync: use super::* in spinlock.rs Boqun Feng
2026-07-31 20:30 ` [PATCH 17/24] rust: sync: Add SpinLockIrq Boqun Feng
2026-07-31 20:30 ` [PATCH 18/24] rust: sync: Introduce SpinLockIrq::lock_with() and friends Boqun Feng
2026-07-31 20:30 ` [PATCH 19/24] rust: sync: Add abstraction for synchronize_rcu() Boqun Feng
2026-07-31 20:30 ` [PATCH 20/24] rust: revocable: Use safe synchronize_rcu() abstraction Boqun Feng
2026-07-31 20:30 ` [PATCH 21/24] rust: sync: Use safe synchronize_rcu() abstraction in poll Boqun Feng
2026-07-31 20:30 ` [PATCH 22/24] rust: sync: Add helpers for mb, dma_mb and friends Boqun Feng
2026-07-31 20:30 ` [PATCH 23/24] rust: sync: Add generic memory barriers Boqun Feng
2026-07-31 20:30 ` [PATCH 24/24] rust: revocable: Use LKMM atomics instead of Rust atomics Boqun Feng

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