linux-kernel - Re: scif_insert

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Date:   Sun, 17 Mar 2019 22:47:40 -0700
From:   Sudeep Dutt <sudeep.dutt@...el.com>
To:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Cc:     Sudeep Dutt <sudeep.dutt@...el.com>, ashutosh.dixit@...el.com,
        linux-kernel@...r.kernel.org
Subject: Re: scif_insert_vma()

On Mon, 2019-03-11 at 08:45 +0200, Jarkko Sakkinen wrote:
> Hi
> 
> Just wondering what will happen if kzalloc() fails in scif_mmap.c. How
> it is recovered? I don't see anything in the VMA callbacks taking care
> of this.

Hi Jarkko,

scif_insert_vma(..) is called from scif_mmap(..) and scif_vma_open(..).
scif_mmap(..) checks for allocation failures but scif_vma_open(..) does
not on purpose.

The vm_operations_struct open(..)/close(..) callbacks do not allow
returning errors. The driver will take a reference to the VMA private
data structure irrespective of whether the allocation during the
open(..) callback succeeds or fails. The close(..) callback cleans up
the data structures from the mmap(..) or open(..) callbacks if any.

Thanks,
Sudeep Dutt