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. This also has the benefit
of tracking more than 16-levels deep if there is ever a need.
Reduce multiple bits in preempt_count for NMI tracking. Reduce NMI_BITS
from 3 to 1, using it only to detect if we're in an NMI.
Suggested-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Joel Fernandes <joelaf@google.com>
3 files changed
