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() calls to just use the NANOSECONDS_PER_SECOND constant.
~~Remove macros IO_READ_PROTO and IO_WRITE_PROTO.~~
Replace calls to object_child_foreach() with object_child_foreach_recursive() when applicable.
Change basename and dirname to g_path_get_basename() and g_path_get_dirname() respectively.
Devices which create MemoryRegions with the old_mmio accessors should be converted to new style mmio accessors.

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().

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.
Use qemu_strtol/qemu_strtoul/qemu_strtoll/qemu_strtoull more.

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.

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

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

Files with conditional debug statements should ensure that the printf is always compiled, and merely hidden behind if (0) when not debugging, rather than #ifdef'd out. This prevents bitrot of the format string of the debug statement. See commit c691320faa6 for an example. Or, go one step further and convert the debug statements to tracepoints.