The spinlock data structure contains two cpu fields for storing the cpu number of the lock holder (one for debug purposes and one for recursive spinlocks). Merging them removes a build time limitation for supporting higher cpu numbers than today.
This series is NOT using more bits for storing the cpu number, but doing that would now be possible. Taking rwlocks into account it would be possible now to use 14 bits for the cpu, allowing up to 16383 cpus without growing the lock related data types. Juergen Gross (2): xen/spinlock: use lock address for lock debug functions xen/spinlock: merge recurse_cpu and debug.cpu fields in struct spinlock xen/arch/x86/mm/mm-locks.h | 6 ++-- xen/common/spinlock.c | 70 ++++++++++++++++++++------------------ xen/include/xen/rwlock.h | 10 +++--- xen/include/xen/spinlock.h | 53 +++++++++++++++++------------ 4 files changed, 76 insertions(+), 63 deletions(-) -- 2.34.1