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Date:   Sat, 11 Mar 2023 14:34:39 +0000
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From:   alyssa@rosenzweig.io
Message-ID: <64cbf509004d6f34831f8257d3d9e82a@rosenzweig.io>
Subject: Re: [PATCH] PCI: apple: Initialize pcie->nvecs before using it
To:     "Sven Peter" <sven@svenpeter.dev>, "Marc Zyngier" <maz@kernel.org>
Cc:     "Lorenzo Pieralisi" <lpieralisi@kernel.org>,
        "=?utf-8?B?S3J6eXN6dG9mIFdpbGN6ecWEc2tp?=" <kw@linux.com>,
        "Rob Herring" <robh@kernel.org>,
        "Bjorn Helgaas" <bhelgaas@google.com>, linux-pci@vger.kernel.org,
        asahi@lists.linux.dev, linux-kernel@vger.kernel.org
In-Reply-To: <20230311133453.63246-1-sven@svenpeter.dev>
References: <20230311133453.63246-1-sven@svenpeter.dev>
Precedence: bulk

Whoops!=0A=0AReviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>=0A=0AM=
arch 11, 2023 8:34 AM, "Sven Peter" <sven@svenpeter.dev> wrote:=0A=0A> ap=
ple_pcie_setup_port computes ilog2(pcie->nvecs) to setup the number of=0A=
> MSIs available for each port. It is however called before apple_msi_ini=
t=0A> which actually initializes pcie->nvecs.=0A> Luckily, pcie->nvecs is=
 part of kzalloc-ed structure and thus=0A> initialized as zero. ilog2(0) =
happens to be 0xffffffff which then just=0A> configures more MSIs in hard=
ware than we actually have. This doesn't=0A> break anything because we ne=
ver hand out those vectors.=0A> Let's swap the order of the two calls so =
that we use the correctly=0A> initialized value.=0A> =0A> Fixes: 476c41ed=
4597 ("PCI: apple: Implement MSI support")=0A> Signed-off-by: Sven Peter =
<sven@svenpeter.dev>=0A> ---=0A> drivers/pci/controller/pcie-apple.c | 6 =
+++++-=0A> 1 file changed, 5 insertions(+), 1 deletion(-)=0A> =0A> diff -=
-git a/drivers/pci/controller/pcie-apple.c b/drivers/pci/controller/pcie-=
apple.c=0A> index 66f37e403a09..8b7b084cf287 100644=0A> --- a/drivers/pci=
/controller/pcie-apple.c=0A> +++ b/drivers/pci/controller/pcie-apple.c=0A=
> @@ -783,6 +783,10 @@ static int apple_pcie_init(struct pci_config_windo=
w *cfg)=0A> cfg->priv =3D pcie;=0A> INIT_LIST_HEAD(&pcie->ports);=0A> =0A=
> + ret =3D apple_msi_init(pcie);=0A> + if (ret)=0A> + return ret;=0A> +=
=0A> for_each_child_of_node(dev->of_node, of_port) {=0A> ret =3D apple_pc=
ie_setup_port(pcie, of_port);=0A> if (ret) {=0A> @@ -792,7 +796,7 @@ stat=
ic int apple_pcie_init(struct pci_config_window *cfg)=0A> }=0A> }=0A> =0A=
> - return apple_msi_init(pcie);=0A> + return 0;=0A> }=0A> =0A> static in=
t apple_pcie_probe(struct platform_device *pdev)=0A> -- =0A> 2.25.1