Contribute/BiteSizedTasks

API conversion

• Look for uses of malloc, and convert them to either g_malloc, g_new (more rarely g_try_malloc or g_try_new if a lot of memory is being allocated). Likewise, convert calloc to either g_new0 or g_try_new0. Drop return value checks unless using g_try_new/g_try_new0.
• Associate external libraries with the object files that actually use them
• For all "QEMUTimer*" variables that are initialized with timer_new, change them to "QEMUTimer" and initialize them with timer_init. Drop any timer_free calls (there aren't many, so this patch would fix small memory leaks too). (not quite bite-sized).
• Replace calls to functions named cpu_physical_memory_* with address_space_*.
• Change net/socket.c to use the functions in include/qemu/sockets.h instead of parse_host_port/bind/connect/listen.
• Change QemuMutex and QemuCond to CompatGMutex and CompatGCond (these are the same as GMutex and GCond, just with a different type). With this change, qemu_mutex_init/qemu_cond_init becomes optional for global variables.
• Change get_ticks_per_sec() to a constant named NSEC_PER_SEC.
• Change qemu_set_fd_handler2 to qemu_set_fd_handler when the second argument is NULL.
• avoid including files from include/exec/cpu-common.h.
• Remove macros IO_READ_PROTO and IO_WRITE_PROTO.

Device models

• Include SDState by value instead of allocating it in sd_init (hw/sd/).
• Look for invocations of qemu_system_reset_request() in hw/. Whenever they correspond to some kind of watchdog that has triggered, change to watchdog_perform_action().

Error checking

• Add checks for NULL return value to uses of load_image_targphys, qemu_find_file.
• Add checks for negative return value to uses of get_image_size, event_notifier_init, msix_init.
• Make unix_connect_opts and inet_connect_opts return negative errno values (instead of -1) upon error.
• Introduce wrappers for strtol/strtoul/strtoll/strtoull, ensuring that errno is checked and, if NULL is passed as the second argument, that the whole string is a number. Example:

   int qemu_strtol(const char *name, const char **next, int base, long *result)
   {
       char *p;
       errno = 0;
       *result = strtol(name, &p, base);
       if (!next && *p) {
           return -EINVAL;
       }
       if (next) {
           *next = p;
       }
       return -errno;
   }

Device lifecycle

• IDE uses qemu_add_vm_change_state_handler() without a corresponding qemu_del_vm_change_state_handler(). This means hot unplugging an AHCI PCI adapter results in a dangling change state handler and could lead to a crash.

Dead code removal

• hw/display contains files named *_template.h. These are included many times with different values of the DEPTH macro. However, only the DEPTH == 32 case is used. Remove support for DEPTH != 32 in the template headers and in the file that include them.
• Look for functions that are named *_exit or *_exitfn in hw/ and that return int. They should all return zero. Make them return void, and remove the checks for the callers.
• Once the above change is done, remove the "Error **" argument from functions named *_unrealize in hw/
• Remove bdrv_aio_multiwrite() since virtio-blk no longer uses it and the only remaining caller, qemu-io, is for testing only

Tracing

• Add tracepoints. All functions that are named something_helper, and all functions mentioned in MemoryRegionOps are good candidates.