Mastering Linux Kernel Development

Data structures

Each SysV semaphore set is represented in the kernel by a descriptor of type struct sem_array:

/* One sem_array data structure for each set of semaphores in the system. */struct sem_array {        struct kern_ipc_perm ____cacheline_aligned_in_smp sem_perm;                                                                                   time_t sem_ctime;               /* last change time */        struct sem *sem_base;           /*ptr to first semaphore in array */        struct list_head pending_alter; /* pending operations */                                        /* that alter the array */        struct list_head pending_const; /* pending complex operations */                                        /* that do not alter semvals */        struct list_head list_id;       /* undo requests on this array */        int sem_nsems;                  /* no. of semaphores in array */        int complex_count;              /* pending complex operations */ bool complex_mode; /* no parallel simple ...