On 11/09/19 21:06, Dr. David Alan Gilbert (git) wrote:
> From: "Dr. David Alan Gilbert" <[email protected]>
>
> RCU_READ_LOCK_AUTO takes the rcu_read_lock and then uses glib's
> g_auto infrastructure (and thus whatever the compiler's hooks are) to
> release it on all exits of the block.
>
> Signed-off-by: Dr. David Alan Gilbert <[email protected]>
> ---
> include/qemu/rcu.h | 18 ++++++++++++++++++
> 1 file changed, 18 insertions(+)
>
> diff --git a/include/qemu/rcu.h b/include/qemu/rcu.h
> index 22876d1428..8768a7b60a 100644
> --- a/include/qemu/rcu.h
> +++ b/include/qemu/rcu.h
> @@ -154,6 +154,24 @@ extern void call_rcu1(struct rcu_head *head, RCUCBFunc
> *func);
> }), \
> (RCUCBFunc *)g_free);
>
> +typedef void RCUReadAuto;
> +static inline RCUReadAuto *rcu_read_auto_lock(void)
> +{
> + rcu_read_lock();
> + /* Anything non-NULL causes the cleanup function to be called */
> + return (void *)0x1;
Doesn't this cause a warning (should be "(void *)(uintptr_t)1" instead)?
> +}
> +
> +static inline void rcu_read_auto_unlock(RCUReadAuto *r)
> +{
> + rcu_read_unlock();
> +}
> +
> +G_DEFINE_AUTOPTR_CLEANUP_FUNC(RCUReadAuto, rcu_read_auto_unlock)
> +
> +#define RCU_READ_LOCK_AUTO \
> + g_autoptr(RCUReadAuto) _rcu_read_auto = rcu_read_auto_lock()
> +
> #ifdef __cplusplus
> }
> #endif
>
Is it possible to make this a scope, like
WITH_RCU_READ_LOCK() {
}
? Perhaps something like
#define WITH_RCU_READ_LOCK() \
WITH_RCU_READ_LOCK_(_rcu_read_auto##__COUNTER__)
#define WITH_RCU_READ_LOCK_(var) \
for (g_autoptr(RCUReadAuto) var = rcu_read_auto_lock();
(var); rcu_read_auto_unlock(), (var) = NULL)
where the dummy variable doubles as an execute-once guard and the gauto
cleanup is still used in case of a "break". I'm not sure if the above
raises a warning because of the variable declaration inside the for
loop, though.
Thanks,
Paolo
