how to read file in kernel(原创)

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it's simple, we just use the vfs func:
char *fw_read_helper(u32* len)
{
        int ret;
        int fd1;
        char *p = NULL;
        mm_segment_t fs;

        fs = get_fs();
        set_fs(KERNEL_DS);

        if(NULL == (p = kmalloc(FW_SIZE_HELPER, GFP_KERNEL))) {
                dpline();
                return NULL;
        }  

        fd1 = sys_open("/helper_gspi.bin", O_RDONLY, S_IRWXU);
        if(fd1 < 0) {
                kfree(p);
                dpline();
                printk("fd is %d\n", fd1);
                return NULL;
        }  

        ret = sys_read(fd1, p, FW_SIZE_HELPER);
        if(ret <= 0) {
                kfree(p);
                sys_close(fd1);
                dpline();
                return NULL;
        }  
        sys_close(fd1);
        set_fs(fs);

        *len = ret;
        return  p; 
        *len = sizeof(helperimage);
        return helperimage;
}