[SOLVED] struct is it declaration or defination or some type of Object Oriented behavior in kernel source

Issue

In r8169_main.c in linux kernel source there is a struct like this

#define KBUILD_MODNAME "foo"

static struct pci_driver rtl8169_pci_driver = {
    .name       = KBUILD_MODNAME,
    .id_table   = rtl8169_pci_tbl,
    .probe      = rtl_init_one,
    .remove     = rtl_remove_one,
    .shutdown   = rtl_shutdown,
    .driver.pm  = pm_ptr(&rtl8169_pm_ops),
};

I like to in first member .name but there is no data type specified and there is . before name like .name = KBUILD_MODNAME, what is it called. is this name member defined somewhere else what this static struct means I did not seen this type of struct before. Can any one please tell what is this and its even assigned a value in struct declaration???

can I also create array of this type of struct?

Solution

what is it called.

name is a member of structure struct pci_driver.

The initialization form is called designated initialization. The part .name = something is designator.

is this name member defined somewhere else

Yes, in include/linux/pci.h.

what this static struct means I did not seen this type of struct before

The line defines a variable rtl8169_pci_driver of type struct pci_driver. The static keyword modifies variable lifetime - it means the variable is valid for the whole duration of the program.

static struct pci_driver rtl8169_pci_driver = {...}
                                            ^^^^^^^ - initialization
                         ^^^^^^^^^^^^^^^^^          - variable name
       ^^^^^^^^^^^^^^^^                             - variable type
^^^^^                                               - storage specifier
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^          - variable declaration
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ - variable definition

Research https://en.cppreference.com/w/c/language/declarations https://en.cppreference.com/w/c/language/struct_initialization https://en.cppreference.com/w/c/language/storage_duration

can I also create array of this type of struct?

You can create arrays of struct pci_drivers.

static struct pci_driver example_array[20] = {
   { .name = initilization_for_first_element, ... },
   { .name = initilization_for_second_element, ... },
   ... etc.
};

Answered By - KamilCuk