qemu/include
Kevin Wolf cfe29d8294 block: Use a single global AioWait
When draining a block node, we recurse to its parent and for subtree
drains also to its children. A single AIO_WAIT_WHILE() is then used to
wait for bdrv_drain_poll() to become true, which depends on all of the
nodes we recursed to. However, if the respective child or parent becomes
quiescent and calls bdrv_wakeup(), only the AioWait of the child/parent
is checked, while AIO_WAIT_WHILE() depends on the AioWait of the
original node.

Fix this by using a single AioWait for all callers of AIO_WAIT_WHILE().

This may mean that the draining thread gets a few more unnecessary
wakeups because an unrelated operation got completed, but we already
wake it up when something _could_ have changed rather than only if it
has certainly changed.

Apart from that, drain is a slow path anyway. In theory it would be
possible to use wakeups more selectively and still correctly, but the
gains are likely not worth the additional complexity. In fact, this
patch is a nice simplification for some places in the code.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
2018-09-25 15:50:15 +02:00
..
block block: Use a single global AioWait 2018-09-25 15:50:15 +02:00
chardev chardev/char-fe: Fix typos 2018-08-23 13:32:50 +02:00
crypto tests: call qcrypto_init instead of gnutls_global_init 2018-07-24 17:33:39 +01:00
disas RISC-V Disassembler 2018-03-07 08:30:28 +13:00
exec ppc: Remove deprecated ppcemb target 2018-08-28 11:31:23 +10:00
fpu softfloat: Add scaling float-to-int routines 2018-08-24 13:17:30 +01:00
hw ppc patch queue 2018-09-25 2018-09-25 13:30:45 +01:00
io qio: non-default context for TLS handshake 2018-03-06 10:19:07 +00:00
libdecnumber
migration vmstate.h: Provide VMSTATE_UINT16_SUB_ARRAY 2018-08-14 17:17:20 +01:00
monitor monitor: Fix unsafe sharing of @cur_mon among threads 2018-07-23 14:00:03 +02:00
net net: Remove the deprecated -tftp, -bootp, -redir and -smb options 2018-08-31 09:53:03 +02:00
qapi Monitor patches for 2018-09-01 2018-09-24 15:43:33 +01:00
qemu blockjob: Lie better in child_job_drained_poll() 2018-09-25 15:50:15 +02:00
qom qom: convert the CPU list to RCU 2018-08-23 18:46:25 +02:00
scsi pr-manager: add query-pr-managers QMP command 2018-06-28 19:05:35 +02:00
standard-headers fw_cfg: import & use linux/qemu_fw_cfg.h 2018-08-23 18:46:25 +02:00
sysemu fw_cfg: ignore suffixes in the bootdevice list dependent on machine class 2018-08-16 22:27:43 -03:00
ui dmabuf: add y0_top, pass it to spice 2018-08-24 08:40:11 +02:00
elf.h elf: Add EM_NANOMIPS value as a valid one for e_machine field 2018-08-24 17:51:59 +02:00
glib-compat.h glib: enforce the minimum required version and warn about old APIs 2018-06-29 12:22:28 +01:00
qemu-common.h qemu-options: Bail out on unsupported options instead of silently ignoring them 2018-05-09 00:13:39 +02:00
qemu-io.h qemu-io: Let command functions return error code 2018-06-11 16:18:45 +02:00
trace-tcg.h trace: get rid of generated-events.h/generated-events.c 2016-10-12 09:54:52 +02:00