linux-kernel - RE: [EXTERNAL] Re: [PATCH rdma-next 1/1] RDMA/mana

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Message-ID:
 <DU8PR83MB0975D8FD2468CFFD7E0AE55CB48EA@DU8PR83MB0975.EURPRD83.prod.outlook.com>
Date: Tue, 13 Jan 2026 14:40:47 +0000
From: Konstantin Taranov <kotaranov@...rosoft.com>
To: Leon Romanovsky <leon@...nel.org>
CC: Konstantin Taranov <kotaranov@...ux.microsoft.com>, Shiraz Saleem
	<shirazsaleem@...rosoft.com>, Long Li <longli@...rosoft.com>, "jgg@...pe.ca"
	<jgg@...pe.ca>, "linux-rdma@...r.kernel.org" <linux-rdma@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [EXTERNAL] Re: [PATCH rdma-next 1/1] RDMA/mana_ib: take CQ type
 from the device type

> On Tue, Jan 13, 2026 at 12:27:57PM +0000, Konstantin Taranov wrote:
> > > >
> > > > -		is_rnic_cq = !!(ucmd.flags & MANA_IB_CREATE_RNIC_CQ);
> > >
> > > You need to add code which prohibits future use of this BIT(0) in
> > > ucmd.flags for backward compatibility and maybe delete
> > > MANA_IB_CREATE_RNIC_CQ from UAPI too.
> > >
> > > Thanks
> > >
> >
> > Hi Leon. I thought that my proposed change is backward and forward
> compatible.
> > If I add code that prohibits this flag, then the older rdma-core will
> > fail to create CQ, as it sets this flag. Add rdma-core should set the flag to
> support older kernels.
> >
> > So, the current solution is as follows:
> > rdma-core always sends the flag. The kernels without this patch still use
> this flag.
> > Newer kernels just ignore the flag and create the CQ according to the client.
> > It is not fully possible to retire this flag now, as we want to be
> > backwards compatible and support older kernels and older rdma-core.
> > Or did you mean something else? Or do I miss something?
> 
> There needs to be a way to document in the code that this bit is reserved
> and must not be used.

Got it! I will add comments to the code that the bit is reserved and should
not be reused.

Thanks

> 
> Thanks
> 
> >
> > Thanks