From: Daniel Scally <djrscally@gmail.com>
To: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>,
Sakari Ailus <sakari.ailus@linux.intel.com>
Cc: linuxarm@huawei.com, mauro.chehab@huawei.com,
Bingbu Cao <bingbu.cao@intel.com>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
Tianshu Qiu <tian.shu.qiu@intel.com>,
Yong Zhi <yong.zhi@intel.com>,
linux-kernel@vger.kernel.org, linux-media@vger.kernel.org
Subject: Re: [PATCH] media: ipu3: don't use recursion at the Kernel
Date: Thu, 2 Dec 2021 12:31:47 +0000 [thread overview]
Message-ID: <1a1437f7-89e9-73f5-a197-c2b7c9536846@gmail.com> (raw)
In-Reply-To: <cf020b6a04b3a9d7f08750927b1d100f63ff4689.1638445455.git.mchehab+huawei@kernel.org>
Hi Mauro
On 02/12/2021 11:44, Mauro Carvalho Chehab wrote:
> The Kernel stack is too small. Doing recursions there is a very
> bad idea, as, if something gets wrong, it could lead to data
> corruption.
TIL - I'll bear that in mind in the future, thanks.
> So, re-implement cio2_check_fwnode_graph() to avoid
> recursion.
>
> Compile-tested only.
>
> Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
FWIW:
Reviewed-by: Daniel Scally <djrscally@gmail.com>
Tested-by: Daniel Scally <djrscally@gmail.com>
> ---
> drivers/media/pci/intel/ipu3/ipu3-cio2-main.c | 17 ++++++++---------
> 1 file changed, 8 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/media/pci/intel/ipu3/ipu3-cio2-main.c b/drivers/media/pci/intel/ipu3/ipu3-cio2-main.c
> index 356ea966cf8d..8e4f250a8b56 100644
> --- a/drivers/media/pci/intel/ipu3/ipu3-cio2-main.c
> +++ b/drivers/media/pci/intel/ipu3/ipu3-cio2-main.c
> @@ -1691,16 +1691,15 @@ static int cio2_check_fwnode_graph(struct fwnode_handle *fwnode)
> {
> struct fwnode_handle *endpoint;
>
> - if (IS_ERR_OR_NULL(fwnode))
> - return -EINVAL;
> -
> - endpoint = fwnode_graph_get_next_endpoint(fwnode, NULL);
> - if (endpoint) {
> - fwnode_handle_put(endpoint);
> - return 0;
> + while (!IS_ERR_OR_NULL(fwnode)) {
> + endpoint = fwnode_graph_get_next_endpoint(fwnode, NULL);
> + if (endpoint) {
> + fwnode_handle_put(endpoint);
> + return 0;
> + }
> + fwnode = fwnode->secondary;
> }
> -
> - return cio2_check_fwnode_graph(fwnode->secondary);
> + return -EINVAL;
> }
>
> /**************** PCI interface ****************/
next prev parent reply other threads:[~2021-12-02 12:32 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-02 11:44 [PATCH] media: ipu3: don't use recursion at the Kernel Mauro Carvalho Chehab
2021-12-02 12:31 ` Daniel Scally [this message]
2021-12-02 12:50 ` Sakari Ailus
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