内核版本:5.14
代码路径:
struct rw_semaphore { atomic_long_t count; atomic_long_t owner; #ifdef CONFIG_RWSEM_SPIN_ON_OWNER struct optimistic_spin_queue osq; /* spinner MCS lock */ #endif raw_spinlock_t wait_lock; struct list_head wait_list; };
实现一个申请和释放读写信号量rwsem_test的内核模块,然后通过应用来控制申请或者释放,期间使用crash工具查看rwsem_test信号量的内部状态。
root@ubuntu-vm:~# crash /mnt/linux-5.14/vmlinux KERNEL: /mnt/linux-5.14/vmlinux DUMPFILE: /dev/mem CPUS: 12 DATE: Sat Mar 26 09:34:29 CST 2022 UPTIME: 00:29:52 LOAD AVERAGE: 0.72, 0.23, 0.08 TASKS: 176 NODENAME: ubuntu-vm RELEASE: 5.14.0+ VERSION: #3 SMP Fri Mar 25 08:57:39 PDT 2022 MACHINE: x86_64 (3599 Mhz) MEMORY: 16 GB PID: 578 COMMAND: "crash" TASK: ffff8de0c595ec80 [THREAD_INFO: ffff8de0c595ec80] CPU: 2 STATE: TASK_RUNNING (ACTIVE) crash> sym rwsem_test ffffffffa5645b00 (d) rwsem_test crash> rw_semaphore.count,owner,wait_list -x ffffffffa5645b00 count = { counter = 0x0 }, owner = { counter = 0x0 }, wait_list = { next = 0xffffffffa5645b18 <rwsem_test+24>, prev = 0xffffffffa5645b18 <rwsem_test+24> }