From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Zhang, Qi Z" <qi.z.zhang@intel.com>
Subject: Re: [PATCH] eal: fix max number of interrupt request
Date: Mon, 13 Feb 2017 01:16:11 +0000
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Cc: "dev@dpdk.org" <dev@dpdk.org>, "Wu, Jingjing" <jingjing.wu@intel.com>
To: Thomas Monjalon <thomas.monjalon@6wind.com>
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Hi Thomas:

> -----Original Message-----
> From: Thomas Monjalon [mailto:thomas.monjalon@6wind.com]
> Sent: Friday, February 10, 2017 6:19 PM
> To: Zhang, Qi Z <qi.z.zhang@intel.com>
> Cc: dev@dpdk.org; Wu, Jingjing <jingjing.wu@intel.com>
> Subject: Re: [PATCH] eal: fix max number of interrupt request
>=20
> 2017-02-09 14:59, Qi Zhang:
> > The max number of interrupt request is possible be changed after
> > rte_intr_callback_register, so in get_max_intr, we need to check if
> > nessesary to update the max_intr.
>=20
> So you are using rte_intr_enable() to update the max_intr field in the ca=
se of
> VFIO_MSIX.
> What about MSI, INTX and UIO cases?

My thought is, even without my fix, VFIO_MSIX is already the only case that=
 try to modify max_intr field=20
In get_max_intr, we have:
				if (!src->intr_handle.max_intr)
                        src->intr_handle.max_intr =3D 1;
                else if (src->intr_handle.max_intr > RTE_MAX_RXTX_INTR_VEC_=
ID)
                        src->intr_handle.max_intr
                                =3D RTE_MAX_RXTX_INTR_VEC_ID + 1;
So my patch just follow this and fix some problem.

Another option is I can use a local variable that assigned by max_intr with=
 boundary check, so get_max_intr can be totally removed and max_intr in int=
r_source will not be modified.

To me both fix are not perfect, I think the problem is in rte_intr_callback=
_register we just save a copy of the pci_dev->intr_handle but not the addre=
ss point, so we are missing some mechanism to sync them.
But since we have tight schedule on the 17.02 release and this issue does c=
ause some example code can't work, so we need to a fix it first, we may con=
sider improve the mechanism later.

Thanks
Qi