thread header¶
The documentation of QEMU’s qemu/thread.h header.
-
void
qemu_thread_atexit_add(struct Notifier * notifier)¶
Parameters
struct Notifier * notifier- Notifier to add
Description
Add the specified notifier to a list which will be run via notifier_list_notify() when this thread exits (either by calling qemu_thread_exit() or by returning from its start_routine). The usual usage is that the caller passes a Notifier which is a per-thread variable; it can then use the callback to free other per-thread data.
If the thread exits as part of the entire process exiting, it is unspecified whether notifiers are called or not.
-
void
qemu_thread_atexit_remove(struct Notifier * notifier)¶
Parameters
struct Notifier * notifier- Notifier to remove
Description
Remove the specified notifier from the thread-exit notification list. It is not valid to try to remove a notifier which is not on the list.
-
void
qemu_lockcnt_init(QemuLockCnt * lockcnt)¶
Parameters
QemuLockCnt * lockcnt- the lockcnt to initialize
Description
Initialize lockcnt’s counter to zero and prepare its mutex for usage.
-
void
qemu_lockcnt_destroy(QemuLockCnt * lockcnt)¶
Parameters
QemuLockCnt * lockcnt- the lockcnt to destruct
Description
Destroy lockcnt’s mutex.
-
void
qemu_lockcnt_inc(QemuLockCnt * lockcnt)¶
Parameters
QemuLockCnt * lockcnt- the lockcnt to operate on
Description
If the lockcnt’s count is zero, wait for critical sections to finish and increment lockcnt’s count to 1. If the count is not zero, just increment it.
Because this function can wait on the mutex, it must not be called while the lockcnt’s mutex is held by the current thread. For the same reason, qemu_lockcnt_inc can also contribute to AB-BA deadlocks. This is a sample deadlock scenario:
- qemu_lockcnt_lock(
lc1);- qemu_lockcnt_lock(
lc2);- qemu_lockcnt_inc(
lc2);- qemu_lockcnt_inc(
lc1);
-
void
qemu_lockcnt_dec(QemuLockCnt * lockcnt)¶
Parameters
QemuLockCnt * lockcnt- the lockcnt to operate on
Parameters
QemuLockCnt * lockcnt- the lockcnt to operate on
Description
possibly lock it. Decrement lockcnt’s count. If the new count is zero, lock the mutex and return true. Otherwise, return false.
Parameters
QemuLockCnt * lockcnt- the lockcnt to operate on
Description
lock it. If the count is 1, decrement the count to zero, lock the mutex and return true. Otherwise, return false.
-
void
qemu_lockcnt_lock(QemuLockCnt * lockcnt)¶
Parameters
QemuLockCnt * lockcnt- the lockcnt to operate on
Description
Remember that concurrent visits are not blocked unless the count is also zero. You can use qemu_lockcnt_count to check for this inside a critical section.
-
void
qemu_lockcnt_unlock(QemuLockCnt * lockcnt)¶
Parameters
QemuLockCnt * lockcnt- the lockcnt to operate on.
-
void
qemu_lockcnt_inc_and_unlock(QemuLockCnt * lockcnt)¶
Parameters
QemuLockCnt * lockcnt- the lockcnt to operate on.
Description
This is the same as
qemu_lockcnt_unlock(lockcnt); qemu_lockcnt_inc(lockcnt);
but more efficient.
-
unsigned
qemu_lockcnt_count(QemuLockCnt * lockcnt)¶
Parameters
QemuLockCnt * lockcnt- the lockcnt to query.
Description
Note that the count can change at any time. Still, while the lockcnt is locked, one can usefully check whether the count is non-zero.