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Message-ID: <20230804173903.2b298cd3@xps-13>
Date: Fri, 4 Aug 2023 17:39:03 +0200
From: Miquel Raynal <miquel.raynal@...tlin.com>
To: Dan Carpenter <dan.carpenter@...aro.org>
Cc: oe-kbuild@...ts.linux.dev,
Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
lkp@...el.com, oe-kbuild-all@...ts.linux.dev,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
Robert Marko <robert.marko@...tura.hr>,
Luka Perkov <luka.perkov@...tura.hr>,
Michael Walle <michael@...le.cc>, linux-kernel@...r.kernel.org,
Randy Dunlap <rdunlap@...radead.org>,
Chen-Yu Tsai <wenst@...omium.org>,
Daniel Golle <daniel@...rotopia.org>,
Rafał Miłecki <rafal@...ecki.pl>
Subject: Re: [PATCH v7 5/7] nvmem: core: Rework layouts to become platform
devices
Hi Dan,
dan.carpenter@...aro.org wrote on Thu, 3 Aug 2023 13:13:04 +0300:
> Hi Miquel,
>
> kernel test robot noticed the following build warnings:
>
> https://git-scm.com/docs/git-format-patch#_base_tree_information]
>
> url: https://github.com/intel-lab-lkp/linux/commits/Miquel-Raynal/nvmem-core-Create-all-cells-before-adding-the-nvmem-device/20230802-022331
> base: char-misc/char-misc-testing
> patch link: https://lore.kernel.org/r/20230801182132.1058707-6-miquel.raynal%40bootlin.com
> patch subject: [PATCH v7 5/7] nvmem: core: Rework layouts to become platform devices
> config: x86_64-randconfig-m001-20230730 (https://download.01.org/0day-ci/archive/20230803/202308030002.DnSFOrMB-lkp@intel.com/config)
> compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
> reproduce: (https://download.01.org/0day-ci/archive/20230803/202308030002.DnSFOrMB-lkp@intel.com/reproduce)
>
> If you fix the issue in a separate patch/commit
> (i.e. not just a new version of the same patch/commit),
(Nice addition, a lot of newcomers would always add these tags
otherwise.)
> kindly add following tags
> | Reported-by: kernel test robot <lkp@...el.com>
> | Reported-by: Dan Carpenter <dan.carpenter@...aro.org>
> | Closes: https://lore.kernel.org/r/202308030002.DnSFOrMB-lkp@intel.com/
>
> New smatch warnings:
> drivers/nvmem/core.c:1003 nvmem_register() warn: 'layout_np' is an error pointer or valid
> drivers/nvmem/core.c:2130 nvmem_try_loading_layout_driver() warn: 'layout_np' is an error pointer or valid
>
> Old smatch warnings:
> drivers/nvmem/core.c:761 nvmem_add_cells_from_fixed_layout() warn: 'layout_np' is an error pointer or valid
> drivers/nvmem/core.c:802 nvmem_layout_get() warn: 'layout_np' is an error pointer or valid
>
> vim +/layout_np +1003 drivers/nvmem/core.c
>
> 266570f496b90d Michael Walle 2023-04-04 1000
> 00d059fd6702f0 Miquel Raynal 2023-08-01 1001 /* Populate layouts as devices */
> 00d059fd6702f0 Miquel Raynal 2023-08-01 1002 layout_np = of_nvmem_layout_get_container(nvmem);
> 00d059fd6702f0 Miquel Raynal 2023-08-01 @1003 if (layout_np) {
>
> So, ugh, of_nvmem_layout_get_container() return NULL on error or error
> pointer if either CONFIG_NVMEM or CONFIG_OF is turned off. I feel like
> that's a mistake. Normally when a function returns both error pointers
> and NULL then the NULL means the feature is disabled and the error
> pointers mean there was an error. Here it is the opposite.
>
> I have written a blog about this:
> https://staticthinking.wordpress.com/2022/08/01/mixing-error-pointers-and-null/
Nice (besides the huge spider which stared at me unexpectedly :-) )
> At first I thought that this was to do with CONFIG_COMPILE_TEST but
> actually that is disabled. The issue here is that CONFIG_OF is turned
> off. So this is a genuine bug, we're compiling a module which will
> always crash.
>
> So I guess the fix is easy that this should return NULL if either
> CONFIG_NVMEM or CONFIG_OF is turned off. That was a long explanation
> which is no longer required now that it's not a COMPILE_TEST issue. :P
I wanted to disable CONFIG_OF to make the test, I totally forget, I'll
handle this case and return NULL when this happens.
However I don't understand why you mention CONFIG_NVMEM, because if it
is not defined, this file will not compile at all?
> 00d059fd6702f0 Miquel Raynal 2023-08-01 1004 rval = of_platform_populate(nvmem->dev.of_node, NULL, NULL, NULL);
> 00d059fd6702f0 Miquel Raynal 2023-08-01 1005 if (rval)
> 00d059fd6702f0 Miquel Raynal 2023-08-01 1006 goto err_remove_cells;
> 00d059fd6702f0 Miquel Raynal 2023-08-01 1007 of_node_put(layout_np);
> 00d059fd6702f0 Miquel Raynal 2023-08-01 1008 }
> 00d059fd6702f0 Miquel Raynal 2023-08-01 1009
> 25c9b5d3aa24a0 Miquel Raynal 2023-08-01 1010 mutex_lock(&nvmem_devices_mutex);
> 25c9b5d3aa24a0 Miquel Raynal 2023-08-01 1011 list_add_tail(&nvmem->node, &nvmem_devices_list);
> 25c9b5d3aa24a0 Miquel Raynal 2023-08-01 1012 mutex_unlock(&nvmem_devices_mutex);
> 25c9b5d3aa24a0 Miquel Raynal 2023-08-01 1013
> f4853e1c321edb Bartosz Golaszewski 2019-02-15 1014 blocking_notifier_call_chain(&nvmem_notifier, NVMEM_ADD, nvmem);
> bee1138bea15a6 Bartosz Golaszewski 2018-09-21 1015
> eace75cfdcf7d9 Srinivas Kandagatla 2015-07-27 1016 return nvmem;
> 3360acdf839170 Johan Hovold 2017-06-09 1017
> b985f4cba6dbb3 Bartosz Golaszewski 2018-09-21 1018 err_remove_cells:
> b985f4cba6dbb3 Bartosz Golaszewski 2018-09-21 1019 nvmem_device_remove_all_cells(nvmem);
> fa72d847d68d78 Bartosz Golaszewski 2018-09-21 1020 if (config->compat)
> ae0c2d725512f3 Srinivas Kandagatla 2019-04-16 1021 nvmem_sysfs_remove_compat(nvmem, config);
> 3360acdf839170 Johan Hovold 2017-06-09 1022 err_put_device:
> 3360acdf839170 Johan Hovold 2017-06-09 1023 put_device(&nvmem->dev);
> 3360acdf839170 Johan Hovold 2017-06-09 1024
> b6c217ab9be689 Andrew Lunn 2016-02-26 1025 return ERR_PTR(rval);
> eace75cfdcf7d9 Srinivas Kandagatla 2015-07-27 1026 }
>
Thanks,
Miquèl
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