diff options
| author | Joel Fernandes <joelagnelf@nvidia.com> | 2026-08-04 09:14:23 -0700 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2026-08-08 22:44:05 +0200 |
| commit | b54aa0edf0594a6e1138e626bfd8a352ed582ae9 (patch) | |
| tree | 28724fee91acfa132bd3bfe9b605bb3bc5b78b4e /kernel | |
| parent | fcb8ada1287227a1392930ee52d7b6c6cab0f0b2 (diff) | |
preempt: Track NMI nesting to separate per-CPU counter
Move NMI nesting tracking from the preempt_count bits to a separate
per-CPU counter (nmi_nesting). This is to free up the NMI bits in the
preempt_count, allowing those bits to be repurposed for other uses.
Reduce NMI_BITS from 4 to 1, using it only to detect if we're in an NMI.
The per-CPU counter currently caps nesting at 15.
[boqun: Address Steven Rostedt's comment on the BUG_ON() condition]
[boqun: Use preempt_count_set() in __nmi_exit() to avoid underflow]
Suggested-by: Boqun Feng <boqun@kernel.org>
Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Boqun Feng <boqun@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260121223933.1568682-3-lyude@redhat.com
Link: https://patch.msgid.link/20260804161447.84806-2-boqun@kernel.org
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/softirq.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/kernel/softirq.c b/kernel/softirq.c index 4425d8dce44b..10af5ed859e7 100644 --- a/kernel/softirq.c +++ b/kernel/softirq.c @@ -88,6 +88,8 @@ EXPORT_PER_CPU_SYMBOL_GPL(hardirqs_enabled); EXPORT_PER_CPU_SYMBOL_GPL(hardirq_context); #endif +DEFINE_PER_CPU(unsigned int, nmi_nesting); + /* * SOFTIRQ_OFFSET usage: * |