Mastering Linux Kernel Development

Data structures

Each shared memory segment is represented by a struct shmid_kernel descriptor. This structure contains all metadata relevant to the management of SysV shared memory:

struct shmid_kernel /* private to the kernel */{        struct kern_ipc_perm shm_perm;        struct file *shm_file; /* pointer to shared memory file */        unsigned long shm_nattch; /* no of attached process */        unsigned long shm_segsz; /* index into the segment */        time_t shm_atim; /* last access time */        time_t shm_dtim; /* last detach time */        time_t shm_ctim; /* last change time */        pid_t shm_cprid; /* pid of creating process */        pid_t shm_lprid; /* pid of last access */        struct user_struct *mlock_user;        /* The task created the shm object. NULL if the task is dead. */ struct task_struct ...