Re: [dpdk-dev] [PATCH] eal/rwlocks: Try read/write and relock write to read locks added.

[Thomas Monjalon <thomas@monjalon.net>]

Hi,

Unfortunately, after 2 months, nobody reviewed this patch.

You could motivate some reviews by providing some explanations
or context of use.


21/05/2018 11:08, Leonid Myravjev:
> From: Leonid Myravjev <myravjev@amicon.ru>
> 
> Signed-off-by: Leonid Myravjev <myravjev@amicon.ru>
> ---
>  lib/librte_eal/common/include/generic/rte_rwlock.h | 61 ++++++++++++++++++++++
>  1 file changed, 61 insertions(+)
> 
> diff --git a/lib/librte_eal/common/include/generic/rte_rwlock.h b/lib/librte_eal/common/include/generic/rte_rwlock.h
> index 899e9bc43..11212e2b8 100644
> --- a/lib/librte_eal/common/include/generic/rte_rwlock.h
> +++ b/lib/librte_eal/common/include/generic/rte_rwlock.h
> @@ -76,6 +76,30 @@ rte_rwlock_read_lock(rte_rwlock_t *rwl)
>  }
>  
>  /**
> + * Try take lock a read lock.
> + *
> + * @param rwl
> + *   A pointer to a rwlock structure.
> + * @return
> + *   1 if the lock is successfully taken; 0 otherwise.
> + */
> +static inline int
> +rte_rwlock_read_trylock(rte_rwlock_t *rwl)
> +{
> +	int32_t x;
> +	int success = 0;
> +
> +	x = rwl->cnt;
> +	/* write lock is held */
> +	if (x < 0)
> +		return 0;
> +	success = rte_atomic32_cmpset((volatile uint32_t *)&rwl->cnt, x, x + 1);
> +	if (success == 0)
> +		return 0;
> +	return 1;
> +}
> +
> +/**
>   * Release a read lock.
>   *
>   * @param rwl
> @@ -110,6 +134,29 @@ rte_rwlock_write_lock(rte_rwlock_t *rwl)
>  					      0, -1);
>  	}
>  }
> +/**
> + * Try take a write lock.
> + *
> + * @param rwl
> + *   A pointer to a rwlock structure.
> + * @return
> + *   1 if the lock is successfully taken; 0 otherwise.
> + */
> +static inline int
> +rte_rwlock_write_trylock(rte_rwlock_t *rwl)
> +{
> +	int32_t x;
> +	int success = 0;
> +
> +	x = rwl->cnt;
> +	/* a lock is held */
> +	if (x != 0)
> +		return 0;
> +	success = rte_atomic32_cmpset((volatile uint32_t *)&rwl->cnt, 0, -1);
> +	if (success == 0)
> +		return 0;
> +	return 1;
> +}
>  
>  /**
>   * Release a write lock.
> @@ -124,6 +171,20 @@ rte_rwlock_write_unlock(rte_rwlock_t *rwl)
>  }
>  
>  /**
> + * Relock write lock to read
> + *
> + * @param rwl
> + *   A pointer to a rwlock structure.
> + */
> +static inline void
> +rte_rwlock_write_relock_read(rte_rwlock_t *rwl)
> +{
> +	rte_atomic32_add((rte_atomic32_t *)(intptr_t)&rwl->cnt, 2);
> +}
> +
> +
> +
> +/**
>   * Try to execute critical section in a hardware memory transaction, if it
>   * fails or not available take a read lock
>   *
>