From: "Fabio M. De Francesco" <fmdefrancesco@gmail.com>
To: Julia Lawall <julia.lawall@inria.fr>, ira.weiny@intel.com
Cc: Alaa Mohamed <eng.alaamohamedsoliman.am@gmail.com>,
outreachy@lists.linux.dev, boris.ostrovsky@oracle.com,
jgross@suse.com, sstabellini@kernel.org,
xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] xen: Convert kmap() to kmap_local_page()
Date: Wed, 20 Apr 2022 15:22:10 +0200 [thread overview]
Message-ID: <2940450.687JKscXgg@leap> (raw)
In-Reply-To: <alpine.DEB.2.22.394.2204200759080.2937@hadrien>
On mercoledì 20 aprile 2022 08:03:05 CEST Julia Lawall wrote:
>
> On Wed, 20 Apr 2022, Alaa Mohamed wrote:
>
> > kmap() is being deprecated and these usages are all local to the thread
> > so there is no reason kmap_local_page() can't be used.
> >
> > Replace kmap() calls with kmap_local_page().
>
> OK, so from a Coccinelle point of view, could we do
>
> @@
> expression e1,e2,x,f;
> @@
>
> e1 =
> - kmap
> + kmap_local_page
> (e2)
> ... when != x = e1 // not stored in any location and not passed to
another function
> when != f(...,e1,...)
> when != x = e2
> when != f(...,e2,...)
> -kunmap(e2)
> +kunmap_local(e1)
>
> julia
>
I've never spent sufficient time to understand properly the syntax and
semantics of expressions of Coccinelle. However, thanks Julia, this code
looks good and can be very helpful.
Only a minor objection... it doesn't tell when 'e2' has been allocated
within the same function where the kmap() call is.
In the particular case that I cite above, I'd prefer to remove the
allocation of the page (say with alloc_page()) and convert kmap() /kunmap()
to use kmalloc() / kfree().
Fox example, this is done in the following patch:
commit 633b0616cfe0 ("x86/sgx: Remove unnecessary kmap() from
sgx_ioc_enclave_init()") from Ira Weiny.
Can Coccinelle catch also those special cases where a page that is passed
to kmap() is allocated within that same function (vs. being passed as
argument to this function) and, if so, propose a replacement with
kmalloc()?
Thanks,
Fabio
next prev parent reply other threads:[~2022-04-20 13:22 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-19 23:43 [PATCH v2] xen: Convert kmap() to kmap_local_page() Alaa Mohamed
2022-04-20 6:03 ` Julia Lawall
2022-04-20 13:22 ` Fabio M. De Francesco [this message]
2022-04-20 13:28 ` Julia Lawall
2022-04-20 13:40 ` Julia Lawall
2022-04-20 13:55 ` Fabio M. De Francesco
2022-04-20 13:57 ` Julia Lawall
2022-04-20 14:07 ` Fabio M. De Francesco
2022-04-25 15:29 ` Ira Weiny
2022-04-25 15:34 ` Julia Lawall
2022-04-21 21:15 ` Boris Ostrovsky
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