[dpdk-dev] [PATCH] net/mlx5: fix event handler uninstall

[Shahaf Shuler]

Hi Slava,

Saturday, May 25, 2019 12:26 PM, Of Viacheslav Ovsiienko:
> Subject: [dpdk-dev] [PATCH] net/mlx5: fix event handler uninstall
> 
> When device is being closed and tries to unregister interrupt callback, there is
> a chance the handler is still active (called in context of eal_intr_thread_main
> thread). If so the rte_intr_callback_unregister returns -EAGAIN and keeps
> the handler registered, causing crash when underlaying resourse is gone
> away.
> 
> This race condition may happen if event handling in application takes a long
> time. We should check the return code of unregistering routine and try again
> to unregister the handler. The diagnostic messages are shown once a
> second, while trying to unregister.
> 
> Fixes: 028b2a28c3cb ("net/mlx5: update event handler for multiport IB
> devices")
> 
> Signed-off-by: Viacheslav Ovsiienko <viacheslavo at mellanox.com>
> Acked-by: Yongseok Koh <yskoh at mellanox.com>
> ---

[...]


> + */
> +void
> +mlx5_intr_callback_unregister(const struct rte_intr_handle *handle,
> +			      rte_intr_callback_fn cb_fn, void *cb_arg) {
> +	/*
> +	 * Try to reduce timeout management overhead by not calling
> +	 * the timer related routines on the first iteration. If the
> +	 * unregistering succeeds on first call there will be no
> +	 * timer calls at all.
> +	 */
> +	uint64_t twait = 0;
> +	uint64_t start = 0;
> +
> +	do {
> +		int ret;
> +
> +		ret = rte_intr_callback_unregister(handle, cb_fn, cb_arg);
> +		if (ret >= 0)
> +			return;
> +		if (ret != -EAGAIN) {
> +			DRV_LOG(INFO, "failed to unregister interrupt"
> +				      " handler (error: %d)", ret);
> +			assert(false);
> +			return;
> +		}
> +		if (twait) {
> +			struct timespec onems;
> +
> +			/* Wait one millisecond and try again. */
> +			onems.tv_sec = 0;
> +			onems.tv_nsec = NS_PER_S / MS_PER_S;

I get the below when trying to compile on top of Bluefield:

/.autodirect/swgwork/shahafs/workspace/dpdk.org/drivers/net/mlx5/mlx5_ethdev.c:1272:20: error: 'NS_PER_S' undeclared (first use in this function); did you mean 'NB_SEGS'?
    onems.tv_nsec = NS_PER_S / MS_PER_S;
                    ^~~~~~~~
                    NB_SEGS
/.autodirect/swgwork/shahafs/workspace/dpdk.org/drivers/net/mlx5/mlx5_ethdev.c:1272:20: note: each undeclared identifier is reported only once for each function it appears in
/.autodirect/swgwork/shahafs/workspace/dpdk.org/drivers/net/mlx5/mlx5_ethdev.c:1272:31: error: 'MS_PER_S' undeclared (first use in this function); did you mean 'NS_PER_S'?
    onems.tv_nsec = NS_PER_S / MS_PER_S;
                               ^~~~~~~~
                               NS_PER_S
/.autodirect/swgwork/shahafs/workspace/dpdk.org/drivers/net/mlx5/mlx5_ethdev.c:1275:9: error: implicit declaration of function 'rte_get_timer_cycles'; did you mean 'rte_get_ptype_name'? [-Werror=implicit-function-declaration]
    if ((rte_get_timer_cycles() - start) <= twait)
         ^~~~~~~~~~~~~~~~~~~~
         rte_get_ptype_name
/.autodirect/swgwork/shahafs/workspace/dpdk.org/drivers/net/mlx5/mlx5_ethdev.c:1275:9: error: nested extern declaration of 'rte_get_timer_cycles' [-Werror=nested-externs]
/.autodirect/swgwork/shahafs/workspace/dpdk.org/drivers/net/mlx5/mlx5_ethdev.c:1284:12: error: implicit declaration of function 'rte_get_timer_hz'; did you mean 'rte_gettid'? [-Werror=implicit-function-declaration]
    twait = rte_get_timer_hz();
            ^~~~~~~~~~~~~~~~
            rte_gettid
/.autodirect/swgwork/shahafs/workspace/dpdk.org/drivers/net/mlx5/mlx5_ethdev.c:1284:12: error: nested extern declaration of 'rte_get_timer_hz' [-Werror=nested-externs]