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qemu: update threading info about domain object refs

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Since commit fd9ef3b31e, virDomainFindByUUIDRef() no longer exists and
all virDomainObjListFindBy*() functions now increment the reference
count.

Signed-off-by: Jonathon Jongsma <jjongsma@redhat.com>
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Reviewed-by: Pavel Hrdina <phrdina@redhat.com>
This commit is contained in:
Jonathon Jongsma 2019-09-04 12:23:30 -05:00 committed by Pavel Hrdina
parent ec78c9a0ff
commit 2029f8269b
1 changed files with 3 additions and 13 deletions
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16
src/qemu/THREADS.txt
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@ -25,27 +25,17 @@ There are a number of locks on various objects
* virDomainObjPtr * virDomainObjPtr
Will be locked after calling any of the virDomainObjListFindBy{ID,Name,UUID} Will be locked and the reference counter will be increased after calling
methods. However, preferred method is qemuDomObjFromDomain() that uses any of the virDomainObjListFindBy{ID,Name,UUID} methods. The preferred way
virDomainFindByUUIDRef() which also increases the reference counter and of decrementing the reference counter and unlocking the domain is using the
finds the domain in the domain list without blocking all other lookups.
When the domain is locked and the reference increased, the preferred way of
decrementing the reference counter and unlocking the domain is using the
virDomainObjEndAPI() function. virDomainObjEndAPI() function.
Lock must be held when changing/reading any variable in the virDomainObjPtr Lock must be held when changing/reading any variable in the virDomainObjPtr
If the lock needs to be dropped & then re-acquired for a short period of
time, the reference count must be incremented first using virDomainObjRef().
There is no need to increase the reference count if qemuDomObjFromDomain()
was used for looking up the domain. In this case there is one reference
already added by that function.
This lock must not be held for anything which sleeps/waits (i.e. monitor This lock must not be held for anything which sleeps/waits (i.e. monitor
commands). commands).
* qemuMonitorPrivatePtr: Job conditions * qemuMonitorPrivatePtr: Job conditions
Since virDomainObjPtr lock must not be held during sleeps, the job Since virDomainObjPtr lock must not be held during sleeps, the job