Re: [dpdk-dev] [PATCH v5 02/20] eal: Allow passing const rte_intr_handle

["Tan, Jianfeng" <jianfeng.tan@intel.com>]

Hi Jan,

> -----Original Message-----
> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Jan Blunck
> Sent: Friday, December 23, 2016 11:58 PM
> To: dev@dpdk.org
> Cc: shreyansh.jain@nxp.com; david.marchand@6wind.com;
> stephen@networkplumber.org
> Subject: [dpdk-dev] [PATCH v5 02/20] eal: Allow passing const
> rte_intr_handle
> 
> Both register/unregister and enable/disable don't necessarily require the
> rte_intr_handle to be modifiable. Therefore lets constify it.
> 
> Signed-off-by: Jan Blunck <jblunck@infradead.org>
> ---
>  lib/librte_eal/bsdapp/eal/eal_interrupts.c     | 24 ++++++----
>  lib/librte_eal/common/include/rte_interrupts.h |  8 ++--
>  lib/librte_eal/linuxapp/eal/eal_interrupts.c   | 62 ++++++++++++++++++----
> ----
>  3 files changed, 63 insertions(+), 31 deletions(-)
> 
> diff --git a/lib/librte_eal/bsdapp/eal/eal_interrupts.c
> b/lib/librte_eal/bsdapp/eal/eal_interrupts.c
> index 836e483..ea2afff 100644
> --- a/lib/librte_eal/bsdapp/eal/eal_interrupts.c
> +++ b/lib/librte_eal/bsdapp/eal/eal_interrupts.c
> @@ -36,29 +36,37 @@
>  #include "eal_private.h"
> 
[...]
> 
> +static int
> +get_max_intr(const struct rte_intr_handle *intr_handle)
> +{
> +	struct rte_intr_source *src;
> +
> +	TAILQ_FOREACH(src, &intr_sources, next) {
> +		if (src->intr_handle.fd != intr_handle->fd)
> +			continue;
> +
> +		if (!src->intr_handle.max_intr)
> +			src->intr_handle.max_intr = 1;
> +		else if (src->intr_handle.max_intr >
> RTE_MAX_RXTX_INTR_VEC_ID)

See "src" instead of intr_handle is used here. "src" is only initialized as calling rte_intr_callback_register at device init phase. But max_intr is usually changed as calling rte_intr_efd_enable() after that. How to make sure max_intr in "src" is valid? And, why shall we use src instead of intr_handle here?

Thanks,
Jianfeng

> +			src->intr_handle.max_intr
> +				= RTE_MAX_RXTX_INTR_VEC_ID + 1;
> +
> +		return src->intr_handle.max_intr;
> +	}
> +
> +	return -1;
> +}
> +
>  /* enable MSI-X interrupts */
>  static int
> -vfio_enable_msix(struct rte_intr_handle *intr_handle) {
> +vfio_enable_msix(const struct rte_intr_handle *intr_handle) {
>  	int len, ret;
>  	char irq_set_buf[MSIX_IRQ_SET_BUF_LEN];
>  	struct vfio_irq_set *irq_set;
> @@ -290,12 +311,15 @@ vfio_enable_msix(struct rte_intr_handle
> *intr_handle) {
> 
>  	irq_set = (struct vfio_irq_set *) irq_set_buf;
>  	irq_set->argsz = len;
> -	if (!intr_handle->max_intr)
> -		intr_handle->max_intr = 1;
> -	else if (intr_handle->max_intr > RTE_MAX_RXTX_INTR_VEC_ID)
> -		intr_handle->max_intr = RTE_MAX_RXTX_INTR_VEC_ID + 1;
> 
> -	irq_set->count = intr_handle->max_intr;
> +	ret = get_max_intr(intr_handle);
> +	if (ret < 0) {
> +		RTE_LOG(ERR, EAL, "Invalid number of MSI-X irqs for
> fd %d\n",
> +			intr_handle->fd);
> +		return -1;
> +	}
> +
> +	irq_set->count = ret;
>  	irq_set->flags = VFIO_IRQ_SET_DATA_EVENTFD |
> VFIO_IRQ_SET_ACTION_TRIGGER;
>  	irq_set->index = VFIO_PCI_MSIX_IRQ_INDEX;
>  	irq_set->start = 0;
> @@ -318,7 +342,7 @@ vfio_enable_msix(struct rte_intr_handle
> *intr_handle) {
>